With all due respect to your ingenuity, which I applaud, I had this exact problem, but had a much easier - and cheaper - solution. I grabbed my neighbor, and together, we struggled up the broken off, but intact, 4'x2' slab until it was resting on its edge. I then shoveled the requisite amount of dirt onto the area, then struggled the slab back down to slightly above level, allowing for compacting of the new dirt. Less than an hour, no jacks, no support beams, no chains, no j-hooks, or drill needed, and didn't spend $16 on spray foam. That was over a year ago, and the slab has now settled to level.
same here. the only thing I caution is to never lift from a corner of the slab (did that on one of mine and broke it off). All the others I lifted from center edge and no issues at all.
As a concrete and foundation inspector employed by a company specializing in poly foam lifting and leveling, I can attest that this method is highly effective. One crucial step not to overlook is the curing time. While commercial-grade poly can solidify in 15 minutes or less, as mentioned in the video, Great Stuff will require a longer curing period. Excellent video, my friend!
Don't the holes directly in the slab potentially cause it to crack? Seems to me the best way would be to insert hoses under the slab and pump it in that way until level.
We had a company come out and do the same thing, but if I was to do it again, I wouldn't let them drill the holes because we got a few cracks now between a couple of the holes. When I was a kid we'd use a breaker bar and just lift the sidewalk and put dirt under it and then put it back down. I think overall, that is the better option and no drilling holes in the cement and trying to match the color later
Thats definitely the best way when its rain and erosion likely moving the dirt over time. That foam can set uneven and definitely stress the block with other gravitational forces.
I laughed because that’s exactly what I would do if I found an uneven sidewalk slab in my yard. This video, although well done, reminds me that sometimes people make things too complicated…
@@overbuiltlimited Where I worked was a workshop and offices attached. The offices started to sink a lot. You feel yourself walking downhill. They drilled some test holes and found it was built over a dump site. There were all sorts of voids. So they raised it back up with concrete under pressure. I though that can't work, you've added even more weight. Sure enough, it raised it for a while then started sinking even quicker. People got sued and the whole place was relocated.
The most valuable part of this demonstration to me was the use of C clamps, jacks and timbers. Raising the slab with such control allows the use of a variety of fill-in support methods. The tip about drilling concrete with a rotary hammer is valuable too; I learned that after struggling with a simple hammer drill.
Thats why you hire reputable professionals. Lifting and trying to back fill at edges won't work. Slab will crack due to voids in a large area. Unreinforced concrete cracks wire mesh doesn't do the job. It bends with the slab over time.
I like that you showed your lifting rig before you made it. It's nice to see what's being made before you make it rather than spending half the demonstration wandering what's being demonstrated. Other youtubers should use this format :)
I paid a concrete leveling company to do this in 15 minutes for $300, but they didn't use spray foam. After they left, I poured dry sand all around the sidewalk section to fill the gaps and packed the soil in, so it can't happen again. I am impressed you were able to do it yourself.
I have done this and it works very well, although I didn't use the jacks, I simply raised the sidewalk slabs with the Great Stuff foam. It will expand and raise the slab on its own, but be careful not to inject too much, because then it could end up being too high. The only thing I would recommend is to save the concrete dust from drilling the holes. Then you can put that on top of the caulk that you put in the holes so it blends perfectly with the existing sidewalk and the holes won't show.
I like your concrete dust idea, but I like his raising and setting better. It has more precise control of the slab's height and level with escape channels for the Great Stuff Big Gap on the sides. You're right when you say it could expand too much.
Well thought out and executed. You’ll probably get comments about easier and less costly ways but remember this you made a clear and clean video. Thank you!
A clearly visible horrible way to accomplish this. Today I, an unlicensed not contractor, is going to show you what they came up with in thier own head. Once again showing people how to do things wrong. Are you seriously telling me you would pay someone to drill holes in your walkway and spray foam it? I would withhold payment and contact the city inspector if that was done professionally.
@@brandonhoffman4712This is what the contractor would do. It’s not just this guys idea. You would “call the inspector” lol. Admittedly the contractor would use a foam with a hardener that would likely last a while longer, but worst case this foam compresses in a decade or two slightly in which case you add a bit more foam. You really seem like the type who has never picked up much more than a screw driver.
@@brandonhoffman4712 ...meanwhile someone claiming to be an inspector above gave their seal of approval on this based on their experience with a company that actually makes this stuff. What are your credentials for stating your position? Also this guy did not simply "dril holes in the sidewalk and spray in foam. He did a lot more as we can see in the video.
@@hiramabiff5236 ive seen inspectors sign off on houses that then wound up full of mold because the plumber didnt do his job right. Thats only 1 horror story. I can fill pages with crap inspectors let fly by due to their book smarts. Go back to school buddy. Tell your inspector buddies to pick up more books too, they arent smart enough.
@@hiramabiff5236 also meanwhile. There are a list of complaints in this comments section from people who have had their slabs crack after having this crap procedure performed. I could be an inspector if i wanted. But then i would have a boss instead of being the boss.
I did something like this about 5 years ago. I had to raise a pad in front of a two step porch/entry. I did all I could to raise it, tracktor & loader, crowbars (big ones), and more. Got it to about right, close as I could get it and stuff all I could under it, including several cans of foam. I also repaired two broken step corners with a concrete mix and forms. It was pretty good, but didn't match. No one complained but I wanted more. So I got some of that polymer resurfacer and did it all plus the 40 ft of sidewalk. All looks great now. And I made the polymer a bit thicker to get the rest of the leveling I couldn't get before. This was a 60 year old sidewalk and step.
I have no issues like this to repair, however I did want to leave a comment because you did a great job of explaining things in a direct manner. Much appreciated!!
I have issues. So did someone else with the cracks they received in thier concrete going from hole to hole... This isn't a fix. Your watching the slowest demolition ever... I mean seriously, spray foaming soil a subsiding property with home insulation gap filler. Does he fix his house leaks with duct tape & bubblegum? Stop watching MacGyver!
Very smart! But if crappy or suspect walkway, suggest scrap of wood (at least 3/4" ply) under each bottle-jack to distribute load… avoid cracking and another project 😀
Yeah. Spreading the load under the jack is essential especially over an unreinforced concrete base. I foolishly assumed a 125mm fully cured slab edge would be OK to use as a base to jack from. Maybe my 20 tonne capacity jack was a bit much but the instant I had the satisfaction of the sound of my lifted slab jump free and move up as I intended, I had the disappointment of seeing the cracks as my relatively new slab cracked right beside my jack. I had watched professional 'mud jackers' on YT and arrogantly assumed it was all just as easy as they made it look. The sheer stress I induced under the jack must have been greater than the lifting force applied to the displaced slab initial resistance.
I've never had an issue with concrete asphalt yes. But this is rated at 3500 lbs per sq in. And that slab he is lifting is only 1/4 yard or 500 lbs max (2000=80 sqft @4"). The 4 lift areas dived by the 4x4" Jacks makes that an over kill.
I did mine differently. I clamped angle iron on the adjacent slab and left the overhang over the slab that I raised. Used this a a stop so it can only be raised to the same level. I used an air hose and a piece of pvc to blow out a few channels under the slab. Simply added foam in the void. It lifted the slab until it hit the angle iron and then the excess simply flowed out the sides. No holes. No jacks.
Anyone concerned the foam might get compressed over time. There is another product made by Loctite called Tite foam. It is advertised as being 4 times as dense as other expanding foams. It has been a long time since I purchased it but it should be comparably priced as other foams and available at many of the same stores.
Not worried. Certain.Urethane spray foam is not weather proof/ It will degrade overtime and if an animal finds it it becomes an easy place to dig. This is a 10 year fix at the outside.
compression is not really an issue because even a several hundred pound slab is only a few pounds per square inch. IOW, hardly anything in the big picture.
Great video. I was really excited when the slab got caught on the rock building pressure and then releasing with a sudden movement. I could not help but think that this was a great analogy of how some earthquakes happen.
I have a customer who was wanting to do this exact same thing. But I told him that wasn't in my wheelhouse and wouldn'tknowwhere to start. . Now I'm going to tell him I can help him get that taken care. Thanks.
Brilliant, one suggestion I use often is save the concrete dust and dust the top of your plugs with the dust. Perfect match to the surface in about a month or two!
Here's a brilliant solution. Just lift the concrete out of the way by standing it on edge. Get a little stone dust or good packing sand. Then level the area to the appropriate hight and lay the slab back down. It's pretty simple. Tools required; lever, fulcrum, sand, level and tamper.
@@shealdedmon7027 At 50 pounds per square foot of 4" slab, that area is going to be heavy with a capital H. Not saying it can't be done as you describe, but that section is probably approaching 500+ pounds.
@@shealdedmon7027 the solid layer of foam will be sufficient to keep the concrete from settling. Foam has been used under concrete for decades now, and works just fine. Most commercial freezers are insulated from below with foam under the concrete floor, dating back to the 60's.
I did this with my sidewalk out front to avoid the city charging me $625 to replace 2 5x5 slabs. Worked perfectly with the c clamp method. The 2nd block had some obstruction so I could not dig on each side. I had to lift by installing 2 5/16 tapcon bolts. Because there was no outlet for the excess foam I ended up overlifting by 1/2 inch so I had to lift the adjacent slab. I used the drill dust and some fine gravel over the self leveling sealant to blend into the existing sidewalk. Looks great. Also found out the foam doesn't yield after it sets up(less than 1 hour). No need to leave everything up overnight.
Very interesting, but I have seem multiple occasions where Great Stuff deteriorated over time, just turning to dust. Also, it was never meant to be load bearing. I'd be very interested in seeing this slab in a year or so to see if this works. Our HOA contracted a company years ago to repair the neighborhood sidewalks and they used grout pumps to both raise and support sinking slabs. It's still working after maybe 15 years. A manual grout pump can be rented for about $75 per day in my area.
Polyurethane foam does not do well if exposed to UV. So it needs to be painted if used outside where light can hit it. Hopefully he did a good job covering up the foam beneath his sidewalk. I have brick steps rising about 3 feet from the garage floor to the kitchen door. One side of the steps is against concrete block foundation, the other side is a crawlspace. When I bought the house there was a hole about 3 inches across through the block next to the steps. I filled it in 30 years ago with foam, until I could get around to using mortar. I was worried about vermin getting under the house. The foam is still there and holding up well.
It's not really bearing load. It's just bearing a few vertical inches of concrete weight for every square inch of Great Stuff. If it were a slab foundation holding up a structure, your point about load-bearing would be well taken.
I am a concrete contractor. This guy did well. Not sure how long it'll hold, but he saved himself some money. Wire mesh, used initially, would stop this heaving, but many don't want wire in their sidewalks, or they don't want to pay for it.
I would never offer that service. My repor with homeowners is critical to me. I don't do half way fixes that destroy a products structural integrity with holes. Someone else can have that job. Maybe a youtuber could swing by and do it... I've had the opportunity to spray foam many fixes over my years in the trades, I've jumped @ none of them. The main thing I use it for is its to seal the bottom of drywall gaps to the floor when I do a self leveling underlayment.
Wire mesh would not have helped here. There is an expansion joint, an obvious separation of the two surfaces. Wire mesh only keeps the slabs from cracking. If the subgrade had been compacted or prepared properly and if water run off is not draining to this joint, this wouldn't have happened. This is not a heaving issue, it is a settling issue. And initially using rebar, not wire mesh would have prevented this, especially if the two sections were poured at two different times, and the old slab could have been drilled and pinned to the new section.
Great demonstration of how to resolve this issue - i know alot of residents have these trip hazards. A final addition to your presentation, is to work out the math on a white board, to show the cost of "remove & replace" verses "lift & support". It was great to watch this. Greg (garden grove, CA)
This is a horrible MacGyver episode. Where MacGyver breaks free from his trip hazard with a drill, insulation gap filler, and 2 shoe laces (still laced in shoes). Today folks, I an unlicensed, not contractor. Is going to show you how to destroy your homes structural integrity. I learned more from Tim the tool man... Like how important a good neigbor is!
I love how you quickly found out your cordless drill wasn’t cutting it. I had the same revelation a couple nights ago trying to reattach loose furring strips behind drywall in my basement. Started off with masonry drill bits and my Milwaukee hammer drill, 45 minutes 2 holes and a dull drill bit later I got a ramset tool and got 10 more done in 15 minutes
This seems like a great method! Previously, I’ve worked on a slab jacking crew. We would do the same thing. We however wouldn’t use “foam” but rather a mixture of Portland cement (to harden), ag lime (as filler), and bentonite (to aid in flow- not sure if it has a purpose out side of that). This mixture was touted as “safe for the environment”. The 2 problems with slab jacking are: 1) cracks happen sometimes 2) typically can’t get things back to “original” but close. With smaller pads, lifting them up with a couple bars and packing dirt under is probably the best bet. Be mindful of erosion and you’ll save yourself a lot of money
@@SoTaSpEaK There is enough water in the soil to make the cement cure with time. The bentonite and lime will also reduce the strength of the mix so that it can move a little bit and reduce the chance of the slab cracking.
Just Grab your angle grinder with a masonry disc and grind the corner of the protruding block off to a comfortable angle. Great vid Stay Happy and Healthy
I was wondering why they didn't do that. You can use the grinder and also one thing that repairs concrete well, is more concrete. I used to drive Illinois and other north-central U.S. states and they often saved money by using concrete slabs on their highways. The better maintained ones would have a crew close a lane from time to time, and they would have a couple guys separated, using huge angle grinders and face shields to smooth out the transitions. Using a toxic plastic foam that is not permeable and not nearly as sturdy as concrete seems a real short-sighted fix.
Put G clamps in a poly back or cover with wide sellotape. It makes the clean up of tools a lot easier. Good project and very clear for beginners. We'll done.
I did a driveway slab this way and I ended up putting foam in the middle but my son and I dug out around the perimeter and added blocks under all the edges after we put down gravel and compacted. Much more work but I feel better that it will last a long time. That was about a year ago and it has not moved one bit. Yet.
I did the same thing but no drilling! I dug the low corners out and put C clamps and a chain joining them. Then with a harbor freight farmers Jack I easily picked it up slightly higher than the other slab. I washed sand and water along the sides into the underside of the slab. Let it dry a day and Dropped the Jack and jumped up and down on it, success!!!
Great video. Here's a idea: instead of drilling through the concrete, as a means of getting the foam pushed into the center, how about inserting tubing under the slab after is it lifted? use these as conduits to spread the foam.
That's a smart idea. I think the process he showed would more often be used for a larger piece or for something where you couldn't get access through the sides.
I don't think it would be bad if that bit of path way is in reasonable condition and the holes you drill are quite a distance away from the edges of the pathway
My thought exactly. I'd rather dig 6 inches around the edges than drill holes. Then just slide A few feet of vacuum hose from the auto parts store into the newly created gap, spray, move around if needed, until the gap is full of foam. I'd still like to give credit to this video for finding an easy way to mimic the professionals. Also, I'd be interested to hear if any of the concerns of this type of foam expanding too much(raising the repair too high) have happened. If so, then it might be wise to use "door and window" spray foam that only fills the gaps but doesn't add extra pressure. Apparently using regular spray foam around doors or windows can expand too much and interfere with opening/closing--the same principle should apply here.
so silly, why do you think the pro's drill? 6 inches in only? your slab will crack in the center eventually ecspecially on a wider bigger piece. Ya''ll in for a world of hurt.. but maybe some I've got a better idea dude will get lucky@@danthomas7862
Perhaps use the foam for lift by shooting some under the center, and packing earth on either side? Gently tamp periodically to try to distribute the foam a bit and keep it from raising up too much? I worry that it'd continue to expand
Great video. We had enough issues that we had sections aligned by a company that pretty much did the same thing. Although I wonder if the foam was the same or less susceptible to long term degradation. You also covered a key thing about dealing the joints, prime point of water entry under the slabs. I used backer rod with Seka sealant, both regular and self leveling, for this. I also lightly spread sand into the sealant while wet, then brushed excess away after fully cured. Makes for a nice appearance.
@@thecloneguyz I will jack the slab and I have an Airplaco hg-5 grout pump that I will pump mortar under the slab with. Did it in my backyard 10 years ago and it is still great.
You did an excellent job lifting it and setting everything back level. When I read the thumbnail I was very sceptical and my first thoughts was that foam will not lift that slab. But once dried it most certainly will hold the slab up.
Foam lifting is for large slabs. It won't help much if you have other problems such as an ant nest under the slab. Better would be to just lift the small slab, deal with any problems that would cause the issue to reoccur, add the appropriate fill material, and lay the slab back down. I've also seen places where the issue isn't settling, but uplift. In those cases, you have to remove tree roots under the lifted section.
I had a professional company try foam under my brick paver front porch after it started to sink in the middle. After 120 lbs of foam, the sides leveled off but in the front near the steps, it was rising. They refunded my money (very expensive) & I had my contractor rip out the pavers and pour a stamped concrete floor with rebar. Turned out great.
1) did you fix the drainage problem that caused it to sink in the first place? If not, it will continue to sink. 2) the foam will compress over time, it's not a structural product. I've tried similar things with a retaining wall and straightening a mailbox on a pylon underground and both failed due to compression of the foam after a couple years.
I would say the foam is a structural product. The compressive strength of the foam will support the concrete. Perhaps the failures you saw were because the compressive strength was exceeded.
Crazy amounts of different spray foams. Pop this small section out and pour new 3’x3’ pad. Cheaper and would last longer. Would drill 3/8 rebar into step and next sidewalk to ensure stability. Would not be surprised a drain spout is near.
1) You are assuming it was a drainage problem. It may just have been un-compacted dirt used during construction. 2) Some foam is a structural product. It is used professionally to raise driveway slabs. It is used to set posts.
@@onjofilms 1) This is not a new walkway and even if it was, if it was only a matter of un-compacted dirt then the adjacent slab would sink too, unless there is a specific extra weight placed on it, for example this happens on driveways where a vehicle is parked.
I’ve been wanting to pay someone to level out my sidewalk out near the street. Had the driveway and patio done a few years ago. Also thought about having the city come out to grind down the bumps. Your video has given me the confidence to do it myself. Wish me luck.
Being as the steps were attached to the slab that was lifted I get why you did it the way you did, it needed to be exact lifts with minimal pressure applied. All of these people commenting about pry bars and such should do some FAFO research. Very nicely executed and with minimal breakage to back or slab.
Great video for small projects. Nice process for curing the problem. The last project my company did before retiring was to raise pavement slabs on US 75. Of course we had industrial grade pumps and the foam pressure lifted the pavement. Your methods work really well for smaller projects like walks and smaller patios! (And the joint sealant video is also really good.)
Interesting idea but much simpler; I lifted each side with a heavy 1” x 6’ breaker bar from HDepot, temporarily stuck a few large rocks to hold it up, removed the bar and dug under with a hand shovel a bit then mixed concrete and shoved it under wherever I could. Next day took out my temp rocks and dressed the dirt edge back up.
Thanks for the video. I tried lifting a sidewalk slab with a 6 foot prybar but wouldnt budge. Good idea to use a jack. I think others may be right that it could be a lot less complicated BUT I'll try another way first and post a video before I either suggest an alternative or eat my hat. Thanks again.
Great video thx! My buddy and his father do driveway leveling and house leveling down in Texas. They actually dig holes on the end needing to be jacked up. They then put inexpensive bottle jacks in the low spots and Jack them up. Afterwards they pump concrete in encasing the jacks and creating a pier. Works really well with large areas on driveways too. No callbacks. Just FYI.
Great video. I would even consider letting the closed cell foam do the work for you. In a rennovation, I added a new tub. The overall contractor doing parts I was not wanted to spray foam under and around the tub instead of my concrete base. Thinking that a metric ton of water is heavy, I said okay, but you own the mistake if there is one. We came back the next day to see how all the work was and the tub was lifted about 1.5" upward breaking the seal to the marble slab it sat on. If we go better at this, we could measure out and do this with spray foam and bypass the manual lifting. I do appreciate the control your way has though.
There's an inadequate subsurface problem that needs to be cleared out and filled with sand or concrete. Foam is porous so it will fill with moisture which will go through a few freeze/thaw cycles in the winter and decompose or rot.
Great DIY approach to fix this problem, I would think that self level floor cement would be better to funnel in the holes as the foam would compress over time and the pad would sink down
Yep, I washed sand into a cavity under the corner of a driveway slab until it was no longer hollow. It worked great. I've done it with large cracks before sealing them too. Play sand works great and flows with water quite well.
I've always tipped the slab on edge, corrected and compacted the bed, and laid it back down again. You save a lot of time excavating, but it can be fiddly getting it leveled out. Still, you're under no time constraints, so you can just tip it back up, add or remove material, and lay it back in. If you have access to fill material, it's a zero-dollar job.
pro tip with these cans ... use needle nose pliers to grip the base of the dispenser 'nub' at the top of the can while you are screwing on the dispenser tube ... this will allow you to create a tight enough seal that foam will not creep into that seal ... also, you can use the cans a second time but to do so, it's best to clean out the plastic tube (assuming you only have the one) before the foam cures ... a long metal wire and/or an air compressor come in handy for this (*only after tube is removed from the can*) ... clean the semi-cured foam out of the nub *gently* as to not damage the nub and the seal inside that is holding back the compressed gas ... wear safety glasses for this ... *even with care, sometimes the cans are still one-use no matter how well you clean them
Amazing amount of engineering. I have lifted pieces of concrete as well. Generally for a sidewalk piece - this size - a large crowbar or 2x4 used as one will lift the slab. Spray foam definitely can lift the slab as well as hold it. What i do - You can lay a couple 2x4s that are min 2’ long each - each side on top of the side walk pieces so their spanning the other unheaved sidewalk. Get your large clamp or even a bar clamp - squeeze the concrete two the 2x4 lifting the slab with a crowbar if even needed. Throw dirt or your foam under there. The pieces are heavy but way more movable then you would first think. Generally if piece is in good condition it goes quick. If cracked you may have a bigger project. The best foundation to put under the lifted concrete is usually add some sand. I pile it into the gap under the lifted slab. You can usually soft the sand in well by using a garden hose and just blast sand from the side - swishing the sand mud under the slab until full.
if they continued to settle again after leveling them, then this might be an indication of a continuous problem going on under your slab, such as erosion from rain water drainage or a leaking sprinkler pipe and even tree roots that are causing shifting in the soil under your slab(s).
Excellent tutorial, right to the point, simple to follow, I id it on my driveway and it work perfectly, my cost $32, instead of the $650 quote from a company. Thanks.
Before everyone "rips into me", let me tell you where I'm coming from. I'm a licensed general contractor for over 30 years so I do know a few things.While I applaud his ingenuity, I cant agree with the material choice. Foam compresses, Its as simple as that.That section of sidewalk probably weighs about 500#. Also, you have to look at why the sidewalk sank in the 1st place. Improper compaction of the soil beneath or something else? Has it stopped sinking? Foundation repair specialists would never repair with foam. They will either use a non-expansive grout or a cement/sand slurry mix. I hope this works, but I think this guy will be making another video in a few years about fixing a sunken sidewalk again.
contractor since 85, i agree. if he has no traffic , it might be fine. If you have a few of us 200#'s walking on it every day and a few years it will be mushed back down. The slurry is the correct way, but for the average homeowner, prying it up (with a bunch of friends, before the beer flows) and packing small stone with a 2x4 underneath, tamping many times from the sides should do the job. the stone will not allow water to collect under the slab to stop the washout from water or water to freeze and heave it.
Agreed as well. All foam products in every application degrade their structural integrity over time (like 5 years, not 100years). From your couch cushions to the insulation in your house. Also, for sure there was an issue with erosion in the first place that needs to be addressed.
I'm NOT knocking your knowledge. I'd appreciate your input. I had Three Big Foundations Companies (ex aqua guard), to come out last year and give me a quote on raising my walkway (the sinking is closest to my front steps, at 2' away it drops). It's also pulling away from the house, on the side where walkway runs. Clamps couldn't be put on Both sides, like here. They were All going to use industrial strength spray foam. They would drill the holes and inject it. None of them would give more than 5 years warranty, because they said this has not been around very long, so they couldn't guarantee it past that. With what some of you guys are saying, about the spray foam compressing, that's probably Why only 5 yr warranty. But their excuse sounded good!! I understand most companies are doing the industrial foam vs mudjacking. What do you think about hydraulic concrete, under it?? It would still have to be raised to get it under there, right? Any advice you can give me, would be much appreciated. Thank you!
I have an opposite problem. My concrete has gaps at the top where it meats my foundation (driveway, stoop, hvac slab) how is this normally addressed and what type of company would I call? Thanks
From an engineering standpoint, this is an awesome video but the practical part of me wants you to pour a new pad! This is a great way to solve the problem without having the mis-match issue though so I see the value.
Also magnitudes more expensive and more work to replace the slab. He has $16 into the foam. If he had to buy the lumber and chains, maybe another $50, but they'll be useful for future projects too.
@@timfischer I disagree. It's $5 at my hardware store for an 80 pound bag of Sakrete for pouring slabs. You might need two or three. A single bottle jack (you need 4) is $25. A single large open mouth C- clamp is $15, and that's all before the chain, hardware or timbers.
Good idea for creating a lift. From doing several of these projects, i always go slightly higher than level or where I want the end result as I find things settle and it extends the time I need to come back and chase my tail. Thanks for sharing👍
I don't have a sidewalk to fix, but you just gave me the perfect method to lift a small shed to put in a new crusher run pad and new floor beams! I knew bottle jacks were part of the equation, but fixing 4X4's to the shed and then lifting the 4X4 with chains might be the ticket. I'll run some calculations to make sure I'm not doing something stupid, though. Thanks - love the channel!
If you have not already done it you could consider strand jacks. They have a hole up through the jack through which you can pass a bar. Pass a bar through your 4x4 (or pair of 4x2) then through another 4x4 at right angles that is supported off the ground. Place jack over bar and secure then jack. Safer than bottle jacks that could tip side ways with you working under shed to prop it to do works.
@@johnclements6614 Haven't done it yet, so your suggestion both appreciated and timely! I'd never heard of strand jacks before, so I'm doing some more googling. What I've found so far looks like the cost would be higher than scrapping the old shed and putting in a new one. Any sources you might be able to recommend?
@@spud13x13 I used a strand jack about twenty years ago for testing bolts that had been epoxied into the side of a bridge. I am in the UK and have not been involved in hiring plant since then. I can not find anything locally to my self with a quick google other than a Chinese site selling small strand jacks for about £400. At that price new I would assume! (big assumption) that be able to hire a couple small jacks, hoses and pump (plus oil etc) for $100 for the weekend if you collected and returned them. I think it would be a case of finding plant hire companies near you that hire jacks then phoning them. The thing about the bottle jacks is you will have to figure out a safe way of doing the work if they tip side ways. I don't know how small your shed is but have you considered moving it. I moved a shed once by taking up the floor, putting some runners under it and levering it along whilst stood inside. Obviously puts stress on all the joints but the shed lasted another ten years till I built a bigger shed.
interesting approach. having set forms and poured slabs I think it's less work and longer lasting to demo the old slab, set a form and mix several bags of concrete.
I totally agree! You can rent a small electric jackhammer, concrete mixer, and buy concrete for a whole lot less money. Secondly, you don’t end up with those noticeable ugly filled drill holes that never blend in with the surrounding concrete. But it does take some skill to finish a poured concrete slab to make it look nice and the color won’t match the old concrete sidewalk.
Did a similar project a few years back, but went very simple - dug down front and rear trenches along each side, used a 6 ft pry bar to lift and level the sidewalk slab and supported the now lifted corners using several large "locally sourced" sandstones set on crushed gravel (created a pier) and then backfilled under the slab with flowable fill I purchased at the local big box store. All in costs were about $30, and the hand digging/levelling/backfill took me about 2 hours from beginning to end. This is a very precise approach, but I'm not sure on the great stuff foam CBA long-term.
Yeah, I did this with a tamper bar and rock as a fulcrum to raise the pad, a rock to support the pad, and dirt tamped in from the side to fill the void. $0. But hey, UA-cam is all about the next quick fix.
@@bkupron that was my original plan since most of the dirt underneath was red clay but, after looking at the space underneath the slab after levelling, I wasn't sure I could get enough compaction to have confidence that most/all voids were filled - that's why I went with the fill.
@@bkitteh6295 look for "Non-Shrink Construction Grout" at any big-box home improvement store; typically ~20 for 50 lbs which would be sufficient for most jobs. It's a cement based product that flows into voids easier than standard bagged cement mix.
Thanks. I literally just lifted a section of my driveway with a hydraulic jack and tractor jack then concreted under it. I've still got a lot more to do and now that the driveway is supported with concrete, I wanted something else to fill in the gaps.
Clamp a timber on the top and as you lift the slabs, clamp it tight to get the top flat, clean the joints out,, then you can either use the foam, or pour free flowing grout to the underside of the slab - shutter the sides to prevent leakage. Remember to heavily grease the end of the clamps that end up under the slab (best to wrap them in plastic too) and yank then out as the fill sets)
@@N20Joe I'd not use foam unless I cemented up the sides. I've seen instances where unexplained floor slab subsidence became very easy to explain after foam was used. There was a trail of foam granules along the narrow gap behind the building that the resident rats had removed to get back inside Of course they now had a super insulated home. The clue is in the name of the product "gap filling foam" it's isn't structural, it might well work, but it's not a true ling term solution, the foam will break down over time, it isn't designed to be saturated and encountered temperature extremes, boats fail because the exact same stuff pumped between the skins form the structure and when wet it crumbles
Great idea! I have the same problem after an armadillo dug a hole under my entrance slab. Going to be a bit of a mission but at least I now know a way to do it, thank you!
I have a garage with 6x6 slabs that make the floor. each slab has sunk in different directions. After watching you do this I think I could take a laser and mark where the top of slabs need to be and hoist them into position. I would pump grout under the slab until it is completely full and give it a few days to cure before releasing the tension off the hoist. I have been looking for a way to do this without demoing the floor and poring all new. After watching your video I clearly see the way to do it. Thanks
I like your technic for lifting the slab. I personally would rather lift a few more inches so I can throw some sand under the slab. Might take a couple tries to get the right height, but better than drilling holes.
I learned that you need to raise the concrete first with a support or bracing. Inject the foam, let foam harden for a few days then remove supports. My step is now level with the rest and holding strong for three years. Caulked the gap with silca self level great.
Recommendation: If the slab is "hanging-up" at the 2 end locations (where the suppressed slab butts up against the other slabs) due to jagged "areas" along the faces of the 2 slabs.... get a Circular Saw with a diamond edge blade... and "run" the blade along the gap area between the 2 slabs. The "cutting" from the diamond blade will remove any jagged areas. This will give smooth faces to each of the abutting slabs and will allow them to "slip past" each other. The gap here is fine, because you will fill this with caulk. If you don't want to fill the full depth, you can fill the void with sand UP to the final 1/2" of the void (as it reaches this surface of the slab). NOTE: The slabs MUST be able to move.
First paragraph is good, second isn’t correct. DO NOT USE SAND. Use backer rod when caulking. Sand will contain the moisture and cause issues if it freezes. The slab does not have to move except on the side connected to the house. A sidewalk typically is only locked on the house side so it can push away. If you remove too much material you will cause the sub grade to wash away and this exact problem will happen again. Although by the that time I would just replace the sidewalk. And this foam will last a year or 2 top and will deteriorate due to the pressure and water.
@@antonioyoutubeaccount5399 I am ONLY recommending placing some sand in the GROOVE between the 2 slabs with sand, in order to FILL THE VOID there... THEN to push backer rod into the upper portion of the groove. The backer rod, along with the caulk, will keep water from migrating into the joint. Because sand is better "graded" than soil, it will NOT retain water unless there is a water source that is "feeding" from underneath. If that is the case, then the slab will move due to frost heave, and the joint is the LEAST of your problems
@@Jaegertiger i COMPLETELY understood WHAT you WERE saying, I will CLARIFY once again THAT sand is a no GO. Just use bacKER roD, then CAULK over it. Source:youtube
This is a very nice job. However, once the concrete was drilled and raised, I would have poured concrete slurry into the holes instead of foam, which will degrade and compact over time.
There is no way you could pour enough slurry into such little holes. It would have to be so watered down that you just end up with a mess and by the time it dries, has lost a large volume and still needs more added but now has an un-uniform spread to to flow through under the slab. It would be better to just lift the entire ends of the slab above the other one and pour in the regular density concrete mix.
Note to those attempting this, one of the problems not encountered in this video (but you might have) is that the edges of the slab may end up beneath the adjacent sections. Due to shifting, the space where the sunken slab was had contracted, so it wasn't possible to simply lift the sunken one. I had to put a masonry blade on my circular saw and carve away enough of the jagged edge so that there was a clean path for the slab to rise through. I'd also agree with other commenters who advised against drilling through the slab. I never went that route, so I didn't end up with cracks, but let me suggest an easier and cheaper approach. The sidewalk is only a few feet across, so you can probably reach the middle from either side. Shove some concrete pads, gravel, and/or whatever else you have handy into the void. If you absolutely must use foam, you can start with several large chunks (i.e., paving stones and the like) and then add the foam between those. At the very least you'll spend less on foam. Rocks are far cheaper and all-natural. Also, I can 2nd the video on the concrete caulk. I applied it all over my 100+ years-old property almost 5 years ago now, and it has held up perfectly. I wasn't willing to repave all the areas with old and badly installed concrete. I used it on the curb alongside the driveway, gaps and cracks in the sidewalk, patio, next to steps, etc., and and in all cases it has not lifted out of the cracks, even after lots of rain, intense summers, and even pressure washing the areas at least 3 times since I applied it. I wish I knew what brand I used in case I have another spot that needs some.
Just curious here, but with the amount of work involved with lifting this small walk area wouldn't it be easier to just break up and pour new in this area?
@@bloody_fobbit2758 That's kinda where I was at here... if you're going to jack up the entire slab, why not just hammer in some thin forms and pour fully plasticized concrete?
I did this same thing only I drilled a couple extra holes in the slb and screwed in a long cement lag screws (instead of the C-clamp method) to attach 2 pieces of chain to then hooked those to my board in which I used a floor jack to raise the end of the cement slab. Great vid and thanks!
Great solution and procedure. An alternative would be to just but out that section that you lifted and pour a new slab. Cost and time this might be cheaper and also better because in a lot of these cases the slab that is being lifted might not be in the best shape.
@@mark-kf3md The material in the background was actually for Plan B if the section of concrete he was raising cracked. The video would have been titled “How to pour a new section of sidewalk”. He was prepared.
@@Steve-ec6ed How is this more expense? He literally said he had $16 into the foam. If he already owned chains and lumber that would be the only cost. Otherwise add $50 for supplies that he can later use on other projects (or lifting more slabs).
I’d be concerned about longevity. Foam breaks down. I I like how you raised it. If you could pour some kind of concrete into the holes or just excavate more on the sides and fill under with gravel.
When my father and I did something like this at his cottage we cut 4" holes into the slab using a concrete hole saw and poured in small-aggregate ready mix concrete with added plasticizer. We ensured it was well distributed and compacted by using a concrete vibrator that was also fed into those holes... you'd think you'd filled the void and then the vibrator would just cause it to disappear so in went more concrete. I think we left the support structure up for a week to allow the concrete plenty of time to cure before taking the weight of the slab.
Clever. Only a little bit more expensive than ripping out that section and a lot more work with a dubious result. Other than that, brillant. Perfect idea for UA-cam DIYers afraid of working with concrete.
I loved the apparatus that was created to raise up the slab in the video. However I guess the slab was only worth about $5 as opposed to the value of the equipment and materials used being maybe $200. Surely just lifting the slab manually and putting an extra layer of sand underneath would have been simpler?
I thought he mentioned at the beginning that the brick was sitting on the same slab he was leveling. If that's the case, you couldn't just lift it out of the way to add more material under it without replacing all the brick.
Most of the problems I see are slabs getting lifted by roots. Sunken slabs are rare and make me worried there's a water issue underneath. Would love to see the easy fix for lowering a slab lifted by roots.
Get 2 cans of spray foam... apply to the base of the tree. Cut the tree down. Remove the lifted slabs... grind the stump and the roots... wait a year pack the area and re-pour as needed.
All sarcasm aside I also wonder if spray foam can overcome an underground water flow issue. It was a great video. Nice use of mechanical advantage but I was wondering how you get spray foam off a c-clamp because basically nothing will get it off my hands
@@timnor4803 Once spray foam is dry, it will rub off of most smooth surfaces. However, if you do like I’ve done, spray foam will never come out of brand new shoes that happen to get a random drop on them!
Instead of all this, just lift the slab out, compact gravel below it & place the slab back again What you are doing is too complicated & not required for a DIYer
Trevor, good point! I would haveJust lifted it up and put a couple of blocks underneath to level it and then, add a length of tubing to the can of foam and insert it into the middle!
Must be an engineer. I never seen anybody make such a complicated project of a simple repair. But I did watch for a minute like a dumbass so mission accomplished.
I would think he could raise it with the jack n c-clamps then pack with rocks using a piece of wood or the pry bar. Then fill the remaining void with foam. I need to lift my patio porch due to stress cracks which have opened up enough for rain water to penetrate and wash away some dirt below the slab. I only recently learned this is what was happening thanks to these type of videos.
Nice well done video. You can save money and time by just wrapping the chains around the beams. No need to buy and install the J-Bolts. I did a similar repair. I did not use great stuff, I would be concerned how it would last over time. I got High density foam sheets and cut to size and slipped in from the sides. This also removes the requirement to drill the holes.
FOUR YEARS AGO, HAD THE SAME PROBLEM. GOT MY PRY BAR, PRYED UP THE SLAB, AND STUFFED SOME GRAVEL UNDER. STILL HOLDING TODAY. DIDN'T SPEND A LOT OF MONEY ON JACKS, CHAINS, AND 4X4 LUMBER.
I applaud your technique. I usually just repour new concrete, but that's a pretty slick hack. I'm curious to know if it still holds true in place five or ten years later.
Lifting up a small concrete slab can be done in a million different ways; one must simply be commonsense-cautious to not crack it. Then, once raised, it's not too difficult to dig a bit to gain access to the underside, from the sides, and then manually fill the cavity with gravel or similar fill. The advantage of the process that I'm describing here is that it does not require procurement of all the items being shown here (wood, jacks, chains, hardware, hammer drill, drill bit, and two cans of foam).
I got a long pry bar. Took up each corner and put some wood wedges to hold it in place. Then used DGA to shove under. Next time I will try the spray foam idea though.
Note for the cost of renting a rotary hammer drill, you can purchase a cheap one from Harbor Freight. Yes the professional ones are a beast and will last for years, but I grabbed a corded 8Amp Bauer for me $67. I'm sure I'll die randomly but I've gotten 7-8 projects out of it and even resorted to doing things I normally wouldn't abuse a drill for (like digging holes and churning compost with auger bits).
With all due respect to your ingenuity, which I applaud, I had this exact problem, but had a much easier - and cheaper - solution. I grabbed my neighbor, and together, we struggled up the broken off, but intact, 4'x2' slab until it was resting on its edge. I then shoveled the requisite amount of dirt onto the area, then struggled the slab back down to slightly above level, allowing for compacting of the new dirt. Less than an hour, no jacks, no support beams, no chains, no j-hooks, or drill needed, and didn't spend $16 on spray foam. That was over a year ago, and the slab has now settled to level.
same here. the only thing I caution is to never lift from a corner of the slab (did that on one of mine and broke it off). All the others I lifted from center edge and no issues at all.
And no holes in the slab to repair .
He’s the type of guy when u work on something together his way is the only way and his ears are blocked
I was just going to say what you said.
step 1 lift slab. step 2 insert dirt. step 3 put slab back where it came from. step 4 the end.
Your solution requires finding and begging a friendly neighbour, his doesn't.
As a concrete and foundation inspector employed by a company specializing in poly foam lifting and leveling, I can attest that this method is highly effective. One crucial step not to overlook is the curing time. While commercial-grade poly can solidify in 15 minutes or less, as mentioned in the video, Great Stuff will require a longer curing period. Excellent video, my friend!
Don't the holes directly in the slab potentially cause it to crack?
Seems to me the best way would be to insert hoses under the slab and pump it in that way until level.
@@walkermom100no. A distribution of holes is needed to get good support underneath.
Thanks Dad...
Since he had Access from the side, why not just fill it with leveling concrete.
This is not a DIY solution. Way to many tools to get this done.
We had a company come out and do the same thing, but if I was to do it again, I wouldn't let them drill the holes because we got a few cracks now between a couple of the holes. When I was a kid we'd use a breaker bar and just lift the sidewalk and put dirt under it and then put it back down. I think overall, that is the better option and no drilling holes in the cement and trying to match the color later
Thats definitely the best way when its rain and erosion likely moving the dirt over time. That foam can set uneven and definitely stress the block with other gravitational forces.
I laughed because that’s exactly what I would do if I found an uneven sidewalk slab in my yard. This video, although well done, reminds me that sometimes people make things too complicated…
@@overbuiltlimited Where I worked was a workshop and offices attached. The offices started to sink a lot. You feel yourself walking downhill. They drilled some test holes and found it was built over a dump site. There were all sorts of voids. So they raised it back up with concrete under pressure. I though that can't work, you've added even more weight. Sure enough, it raised it for a while then started sinking even quicker. People got sued and the whole place was relocated.
That is the best method, because with Winter frost water will freeze under that foam and may lift that area.
You actually had a company that did the same thing. That's interesting.
The most valuable part of this demonstration to me was the use of C clamps, jacks and timbers. Raising the slab with such control allows the use of a variety of fill-in support methods.
The tip about drilling concrete with a rotary hammer is valuable too; I learned that after struggling with a simple hammer drill.
Thats why you hire reputable professionals. Lifting and trying to back fill at edges won't work. Slab will crack due to voids in a large area. Unreinforced concrete cracks wire mesh doesn't do the job. It bends with the slab over time.
It's literally 3 bags of concrete. Remove and replace is your best option
@@travishanks7295 LOL exactly
I like that you showed your lifting rig before you made it. It's nice to see what's being made before you make it rather than spending half the demonstration wandering what's being demonstrated.
Other youtubers should use this format :)
Thanks for simple , to the point video. You do not talk about your puppies , neighbors or other unnecessary items.
Right!
Lol
But at least you took the time to discuss them…perspective is everything.
😂right!
He's got puppies?
I paid a concrete leveling company to do this in 15 minutes for $300, but they didn't use spray foam. After they left, I poured dry sand all around the sidewalk section to fill the gaps and packed the soil in, so it can't happen again. I am impressed you were able to do it yourself.
I have done this and it works very well, although I didn't use the jacks, I simply raised the sidewalk slabs with the Great Stuff foam. It will expand and raise the slab on its own, but be careful not to inject too much, because then it could end up being too high.
The only thing I would recommend is to save the concrete dust from drilling the holes. Then you can put that on top of the caulk that you put in the holes so it blends perfectly with the existing sidewalk and the holes won't show.
That’s why he raised it first so the excess woukd or could glow out holes
I like your concrete dust idea, but I like his raising and setting better. It has more precise control of the slab's height and level with escape channels for the Great Stuff Big Gap on the sides. You're right when you say it could expand too much.
" I simply raised the sidewalk slabs with the Great Stuff foam" ?????
@@rufflesinc the contractor's way is to foam jack a slab, but with that lil fella the method shown is most effective.
Thank you I was going to ask about that because I have a part I can’t raise but I know is sinking. It’s a slab.
Well thought out and executed. You’ll probably get comments about easier and less costly ways but remember this you made a clear and clean video.
Thank you!
A clearly visible horrible way to accomplish this.
Today I, an unlicensed not contractor, is going to show you what they came up with in thier own head. Once again showing people how to do things wrong.
Are you seriously telling me you would pay someone to drill holes in your walkway and spray foam it? I would withhold payment and contact the city inspector if that was done professionally.
@@brandonhoffman4712This is what the contractor would do. It’s not just this guys idea. You would “call the inspector” lol. Admittedly the contractor would use a foam with a hardener that would likely last a while longer, but worst case this foam compresses in a decade or two slightly in which case you add a bit more foam. You really seem like the type who has never picked up much more than a screw driver.
@@brandonhoffman4712 ...meanwhile someone claiming to be an inspector above gave their seal of approval on this based on their experience with a company that actually makes this stuff. What are your credentials for stating your position?
Also this guy did not simply "dril holes in the sidewalk and spray in foam. He did a lot more as we can see in the video.
@@hiramabiff5236 ive seen inspectors sign off on houses that then wound up full of mold because the plumber didnt do his job right. Thats only 1 horror story. I can fill pages with crap inspectors let fly by due to their book smarts.
Go back to school buddy. Tell your inspector buddies to pick up more books too, they arent smart enough.
@@hiramabiff5236 also meanwhile. There are a list of complaints in this comments section from people who have had their slabs crack after having this crap procedure performed.
I could be an inspector if i wanted. But then i would have a boss instead of being the boss.
I love your communications skills, the way you talk throughout the activity is key. Excellent brother !
I did something like this about 5 years ago. I had to raise a pad in front of a two step porch/entry. I did all I could to raise it, tracktor & loader, crowbars (big ones), and more. Got it to about right, close as I could get it and stuff all I could under it, including several cans of foam.
I also repaired two broken step corners with a concrete mix and forms. It was pretty good, but didn't match. No one complained but I wanted more.
So I got some of that polymer resurfacer and did it all plus the 40 ft of sidewalk.
All looks great now. And I made the polymer a bit thicker to get the rest of the leveling I couldn't get before. This was a 60 year old sidewalk and step.
I have just gotten one step closer to being the smartest man on Earth
I have no issues like this to repair, however I did want to leave a comment because you did a great job of explaining things in a direct manner. Much appreciated!!
I have issues. So did someone else with the cracks they received in thier concrete going from hole to hole...
This isn't a fix. Your watching the slowest demolition ever...
I mean seriously, spray foaming soil a subsiding property with home insulation gap filler.
Does he fix his house leaks with duct tape & bubblegum?
Stop watching MacGyver!
Very smart! But if crappy or suspect walkway, suggest scrap of wood (at least 3/4" ply) under each bottle-jack to distribute load… avoid cracking and another project 😀
Yeah. Spreading the load under the jack is essential especially over an unreinforced concrete base. I foolishly assumed a 125mm fully cured slab edge would be OK to use as a base to jack from. Maybe my 20 tonne capacity jack was a bit much but the instant I had the satisfaction of the sound of my lifted slab jump free and move up as I intended, I had the disappointment of seeing the cracks as my relatively new slab cracked right beside my jack. I had watched professional 'mud jackers' on YT and arrogantly assumed it was all just as easy as they made it look. The sheer stress I induced under the jack must have been greater than the lifting force applied to the displaced slab initial resistance.
I've never had an issue with concrete asphalt yes. But this is rated at 3500 lbs per sq in. And that slab he is lifting is only 1/4 yard or 500 lbs max (2000=80 sqft @4"). The 4 lift areas dived by the 4x4" Jacks makes that an over kill.
I did mine differently. I clamped angle iron on the adjacent slab and left the overhang over the slab that I raised. Used this a a stop so it can only be raised to the same level. I used an air hose and a piece of pvc to blow out a few channels under the slab. Simply added foam in the void. It lifted the slab until it hit the angle iron and then the excess simply flowed out the sides. No holes. No jacks.
Anyone concerned the foam might get compressed over time. There is another product made by Loctite called Tite foam. It is advertised as being 4 times as dense as other expanding foams. It has been a long time since I purchased it but it should be comparably priced as other foams and available at many of the same stores.
Not worried. Certain.Urethane spray foam is not weather proof/ It will degrade overtime and if an animal finds it it becomes an easy place to dig. This is a 10 year fix at the outside.
compression is not really an issue because even a several hundred pound slab is only a few pounds per square inch. IOW, hardly anything in the big picture.
Concerned? I don't care.
Great video. I was really excited when the slab got caught on the rock building pressure and then releasing with a sudden movement. I could not help but think that this was a great analogy of how some earthquakes happen.
I have a customer who was wanting to do this exact same thing. But I told him that wasn't in my wheelhouse and wouldn'tknowwhere to start. . Now I'm going to tell him I can help him get that taken care. Thanks.
Brilliant, one suggestion I use often is save the concrete dust and dust the top of your plugs with the dust. Perfect match to the surface in about a month or two!
Here's a brilliant solution. Just lift the concrete out of the way by standing it on edge. Get a little stone dust or good packing sand. Then level the area to the appropriate hight and lay the slab back down. It's pretty simple. Tools required; lever, fulcrum, sand, level and tamper.
@@shealdedmon7027 At 50 pounds per square foot of 4" slab, that area is going to be heavy with a capital H. Not saying it can't be done as you describe, but that section is probably approaching 500+ pounds.
@@shealdedmon7027 the solid layer of foam will be sufficient to keep the concrete from settling. Foam has been used under concrete for decades now, and works just fine. Most commercial freezers are insulated from below with foam under the concrete floor, dating back to the 60's.
@@5thGenNativeTexan No problem with the “power” of leverage and having a good size breaker bar or Johnson bar.
This is gold, My company does poly level and can lift and support sunken in walkways, driveways, roads ect but it is costly.
I did this with my sidewalk out front to avoid the city charging me $625 to replace 2 5x5 slabs. Worked perfectly with the c clamp method. The 2nd block had some obstruction so I could not dig on each side. I had to lift by installing 2 5/16 tapcon bolts. Because there was no outlet for the excess foam I ended up overlifting by 1/2 inch so I had to lift the adjacent slab. I used the drill dust and some fine gravel over the self leveling sealant to blend into the existing sidewalk. Looks great. Also found out the foam doesn't yield after it sets up(less than 1 hour). No need to leave everything up overnight.
Very interesting, but I have seem multiple occasions where Great Stuff deteriorated over time, just turning to dust.
Also, it was never meant to be load bearing.
I'd be very interested in seeing this slab in a year or so to see if this works.
Our HOA contracted a company years ago to repair the neighborhood sidewalks and they used grout pumps to both raise and support sinking slabs. It's still working after maybe 15 years.
A manual grout pump can be rented for about $75 per day in my area.
Polyurethane foam does not do well if exposed to UV. So it needs to be painted if used outside where light can hit it. Hopefully he did a good job covering up the foam beneath his sidewalk. I have brick steps rising about 3 feet from the garage floor to the kitchen door. One side of the steps is against concrete block foundation, the other side is a crawlspace. When I bought the house there was a hole about 3 inches across through the block next to the steps. I filled it in 30 years ago with foam, until I could get around to using mortar. I was worried about vermin getting under the house. The foam is still there and holding up well.
It won't deteriorate if protected from sun and air.
Seems like a short term fix with lots of equipment to me. Just have some friends, lift this thing off, and add gravel and done...
Yes true 👍 🙌 👏
It's not really bearing load. It's just bearing a few vertical inches of concrete weight for every square inch of Great Stuff. If it were a slab foundation holding up a structure, your point about load-bearing would be well taken.
I am a concrete contractor. This guy did well. Not sure how long it'll hold, but he saved himself some money. Wire mesh, used initially, would stop this heaving, but many don't want wire in their sidewalks, or they don't want to pay for it.
I would never offer that service.
My repor with homeowners is critical to me. I don't do half way fixes that destroy a products structural integrity with holes.
Someone else can have that job. Maybe a youtuber could swing by and do it...
I've had the opportunity to spray foam many fixes over my years in the trades, I've jumped @ none of them. The main thing I use it for is its to seal the bottom of drywall gaps to the floor when I do a self leveling underlayment.
Wire mesh would not have helped here. There is an expansion joint, an obvious separation of the two surfaces. Wire mesh only keeps the slabs from cracking. If the subgrade had been compacted or prepared properly and if water run off is not draining to this joint, this wouldn't have happened. This is not a heaving issue, it is a settling issue. And initially using rebar, not wire mesh would have prevented this, especially if the two sections were poured at two different times, and the old slab could have been drilled and pinned to the new section.
Great demonstration of how to resolve this issue - i know alot of residents have these trip hazards. A final addition to your presentation, is to work out the math on a white board, to show the cost of "remove & replace" verses "lift & support". It was great to watch this. Greg (garden grove, CA)
This is a horrible MacGyver episode. Where MacGyver breaks free from his trip hazard with a drill, insulation gap filler, and 2 shoe laces (still laced in shoes).
Today folks, I an unlicensed, not contractor. Is going to show you how to destroy your homes structural integrity.
I learned more from Tim the tool man... Like how important a good neigbor is!
I love how you quickly found out your cordless drill wasn’t cutting it. I had the same revelation a couple nights ago trying to reattach loose furring strips behind drywall in my basement. Started off with masonry drill bits and my Milwaukee hammer drill, 45 minutes 2 holes and a dull drill bit later I got a ramset tool and got 10 more done in 15 minutes
Lol, cordless = toy. They definitely have their place, but batteries don't compare to line voltage.
This seems like a great method!
Previously, I’ve worked on a slab jacking crew. We would do the same thing. We however wouldn’t use “foam” but rather a mixture of Portland cement (to harden), ag lime (as filler), and bentonite (to aid in flow- not sure if it has a purpose out side of that). This mixture was touted as “safe for the environment”.
The 2 problems with slab jacking are:
1) cracks happen sometimes
2) typically can’t get things back to “original” but close.
With smaller pads, lifting them up with a couple bars and packing dirt under is probably the best bet.
Be mindful of erosion and you’ll save yourself a lot of money
Bentonite expands as part of the curing process. I'll have to remember to use some of it next time I do this.
@@CrabgrassFarmer yes I wonder if it retaining water would allow for the Portland to not cure correctly. It seemed like it worked when we did it.
@@SoTaSpEaK There is enough water in the soil to make the cement cure with time.
The bentonite and lime will also reduce the strength of the mix so that it can move a little bit and reduce the chance of the slab cracking.
@@johnclements6614 I see. Thanks for clarifying that.
Just Grab your angle grinder with a masonry disc and grind the corner of the protruding block off to a comfortable angle.
Great vid Stay Happy and Healthy
I was wondering why they didn't do that. You can use the grinder and also one thing that repairs concrete well, is more concrete. I used to drive Illinois and other north-central U.S. states and they often saved money by using concrete slabs on their highways.
The better maintained ones would have a crew close a lane from time to time, and they would have a couple guys separated, using huge angle grinders and face shields to smooth out the transitions. Using a toxic plastic foam that is not permeable and not nearly as sturdy as concrete seems a real short-sighted fix.
Put G clamps in a poly back or cover with wide sellotape. It makes the clean up of tools a lot easier.
Good project and very clear for beginners. We'll done.
Just perfect. I probably add 4 large rocks wedged at each corner. Big difference and very clean look
I agree. The foam may be sturdy, but it has give and will move more than a solid object.
I did a driveway slab this way and I ended up putting foam in the middle but my son and I dug out around the perimeter and added blocks under all the edges after we put down gravel and compacted. Much more work but I feel better that it will last a long time. That was about a year ago and it has not moved one bit. Yet.
I did the same thing but no drilling! I dug the low corners out and put C clamps and a chain joining them. Then with a harbor freight farmers Jack I easily picked it up slightly higher than the other slab. I washed sand and water along the sides into the underside of the slab. Let it dry a day and Dropped the Jack and jumped up and down on it, success!!!
Great video. Here's a idea: instead of drilling through the concrete, as a means of getting the foam pushed into the center, how about inserting tubing under the slab after is it lifted? use these as conduits to spread the foam.
That's a smart idea. I think the process he showed would more often be used for a larger piece or for something where you couldn't get access through the sides.
I don't think it would be bad if that bit of path way is in reasonable condition and the holes you drill are quite a distance away from the edges of the pathway
My thought exactly. I'd rather dig 6 inches around the edges than drill holes. Then just slide A few feet of vacuum hose from the auto parts store into the newly created gap, spray, move around if needed, until the gap is full of foam. I'd still like to give credit to this video for finding an easy way to mimic the professionals.
Also, I'd be interested to hear if any of the concerns of this type of foam expanding too much(raising the repair too high) have happened. If so, then it might be wise to use "door and window" spray foam that only fills the gaps but doesn't add extra pressure. Apparently using regular spray foam around doors or windows can expand too much and interfere with opening/closing--the same principle should apply here.
so silly, why do you think the pro's drill? 6 inches in only? your slab will crack in the center eventually ecspecially on a wider bigger piece. Ya''ll in for a world of hurt.. but maybe some I've got a better idea dude will get lucky@@danthomas7862
Perhaps use the foam for lift by shooting some under the center, and packing earth on either side? Gently tamp periodically to try to distribute the foam a bit and keep it from raising up too much?
I worry that it'd continue to expand
Cool fix and this is why you should use rebar when pouring concrete in the first place
Great video. We had enough issues that we had sections aligned by a company that pretty much did the same thing. Although I wonder if the foam was the same or less susceptible to long term degradation.
You also covered a key thing about dealing the joints, prime point of water entry under the slabs. I used backer rod with Seka sealant, both regular and self leveling, for this. I also lightly spread sand into the sealant while wet, then brushed excess away after fully cured. Makes for a nice appearance.
They actually make a load-bearing foam for doing this I don't know why people keep using the air blocking foam
@@thecloneguyz I will jack the slab and I have an Airplaco hg-5 grout pump that I will pump mortar under the slab with. Did it in my backyard 10 years ago and it is still great.
You did an excellent job lifting it and setting everything back level. When I read the thumbnail I was very sceptical and my first thoughts was that foam will not lift that slab. But once dried it most certainly will hold the slab up.
Question, if you already lifted up the slab, lift it higher and put more rock and sand underneath?
Foam lifting is for large slabs. It won't help much if you have other problems such as an ant nest under the slab. Better would be to just lift the small slab, deal with any problems that would cause the issue to reoccur, add the appropriate fill material, and lay the slab back down. I've also seen places where the issue isn't settling, but uplift. In those cases, you have to remove tree roots under the lifted section.
That's amazing, you should make a video
COOL STORY BRO
Ants would not stop foam but would be a dead ant nest
I had a professional company try foam under my brick paver front porch after it started to sink in the middle. After 120 lbs of foam, the sides leveled off but in the front near the steps, it was rising. They refunded my money (very expensive) & I had my contractor rip out the pavers and pour a stamped concrete floor with rebar. Turned out great.
@@Etron49 That's what I thought about halfway through the video.
1) did you fix the drainage problem that caused it to sink in the first place? If not, it will continue to sink.
2) the foam will compress over time, it's not a structural product. I've tried similar things with a retaining wall and straightening a mailbox on a pylon underground and both failed due to compression of the foam after a couple years.
Makes sense. Surprised he didn't insert some bricks or inject some concrete in the sides to guarantee it will never sink.
I would say the foam is a structural product. The compressive strength of the foam will support the concrete. Perhaps the failures you saw were because the compressive strength was exceeded.
Crazy amounts of different spray foams. Pop this small section out and pour new 3’x3’ pad. Cheaper and would last longer. Would drill 3/8 rebar into step and next sidewalk to ensure stability. Would not be surprised a drain spout is near.
1) You are assuming it was a drainage problem. It may just have been un-compacted dirt used during construction.
2) Some foam is a structural product. It is used professionally to raise driveway slabs. It is used to set posts.
@@onjofilms 1) This is not a new walkway and even if it was, if it was only a matter of un-compacted dirt then the adjacent slab would sink too, unless there is a specific extra weight placed on it, for example this happens on driveways where a vehicle is parked.
I’ve been wanting to pay someone to level out my sidewalk out near the street. Had the driveway and patio done a few years ago. Also thought about having the city come out to grind down the bumps. Your video has given me the confidence to do it myself. Wish me luck.
Being as the steps were attached to the slab that was lifted I get why you did it the way you did, it needed to be exact lifts with minimal pressure applied. All of these people commenting about pry bars and such should do some FAFO research. Very nicely executed and with minimal breakage to back or slab.
Great video for small projects. Nice process for curing the problem. The last project my company did before retiring was to raise pavement slabs on US 75. Of course we had industrial grade pumps and the foam pressure lifted the pavement. Your methods work really well for smaller projects like walks and smaller patios! (And the joint sealant video is also really good.)
All the hardware and materials needed, just remove slab make a new one
Interesting idea but much simpler; I lifted each side with a heavy 1” x 6’ breaker bar from HDepot, temporarily stuck a few large rocks to hold it up, removed the bar and dug under with a hand shovel a bit then mixed concrete and shoved it under wherever I could. Next day took out my temp rocks and dressed the dirt edge back up.
Can we see the video?
Thanks for the video. I tried lifting a sidewalk slab with a 6 foot prybar but wouldnt budge.
Good idea to use a jack.
I think others may be right that it could be a lot less complicated BUT I'll try another way first and post a video before I either suggest an alternative or eat my hat.
Thanks again.
Great video thx! My buddy and his father do driveway leveling and house leveling down in Texas. They actually dig holes on the end needing to be jacked up. They then put inexpensive bottle jacks in the low spots and Jack them up. Afterwards they pump concrete in encasing the jacks and creating a pier. Works really well with large areas on driveways too. No callbacks. Just FYI.
Great video. I would even consider letting the closed cell foam do the work for you. In a rennovation, I added a new tub. The overall contractor doing parts I was not wanted to spray foam under and around the tub instead of my concrete base. Thinking that a metric ton of water is heavy, I said okay, but you own the mistake if there is one. We came back the next day to see how all the work was and the tub was lifted about 1.5" upward breaking the seal to the marble slab it sat on. If we go better at this, we could measure out and do this with spray foam and bypass the manual lifting. I do appreciate the control your way has though.
Great job lifting it and making the video. For the gap, I prefer Sika Flex self-leveling sealant.
Excellent tutorial - you have shown a really reasonable method for fixing a sunken sidewalk slab. Thank you.
ggs113
ggs113
1 second ago
I second the comment, Sharon.
Did anyone else think it was just going to take the spray foam to accomplish this? Asking for a friend.
I’m too committed now. Time for some bottle jacks and posts
Yes
Yes.clickbait.
At this rate, it’s better to just redo that small block! I think it would have been cheaper and quicker.
Yes. Way too much work. Lol
There's an inadequate subsurface problem that needs to be cleared out and filled with sand or concrete. Foam is porous so it will fill with moisture which will go through a few freeze/thaw cycles in the winter and decompose or rot.
Great idea using bottle jacks!! I've been trying to figure out a way to lift slab aside from renting a skid steer this is awesome.
Great DIY approach to fix this problem, I would think that self level floor cement would be better to funnel in the holes as the foam would compress over time and the pad would sink down
Exactly my thought. This would end up compressing at some point. Cement would be the way to go, I think.
Yep, I washed sand into a cavity under the corner of a driveway slab until it was no longer hollow. It worked great. I've done it with large cracks before sealing them too. Play sand works great and flows with water quite well.
I've always tipped the slab on edge, corrected and compacted the bed, and laid it back down again. You save a lot of time excavating, but it can be fiddly getting it leveled out. Still, you're under no time constraints, so you can just tip it back up, add or remove material, and lay it back in. If you have access to fill material, it's a zero-dollar job.
pro tip with these cans ... use needle nose pliers to grip the base of the dispenser 'nub' at the top of the can while you are screwing on the dispenser tube ... this will allow you to create a tight enough seal that foam will not creep into that seal ... also, you can use the cans a second time but to do so, it's best to clean out the plastic tube (assuming you only have the one) before the foam cures ... a long metal wire and/or an air compressor come in handy for this (*only after tube is removed from the can*) ... clean the semi-cured foam out of the nub *gently* as to not damage the nub and the seal inside that is holding back the compressed gas ... wear safety glasses for this ... *even with care, sometimes the cans are still one-use no matter how well you clean them
I clean the nub out with brake cleaner afterwards and can usually reuse partially used cans no problem.
Amazing amount of engineering. I have lifted pieces of concrete as well.
Generally for a sidewalk piece - this size - a large crowbar or 2x4 used as one will lift the slab. Spray foam definitely can lift the slab as well as hold it.
What i do - You can lay a couple 2x4s that are min 2’ long each - each side on top of the side walk pieces so their spanning the other unheaved sidewalk. Get your large clamp or even a bar clamp - squeeze the concrete two the 2x4 lifting the slab with a crowbar if even needed. Throw dirt or your foam under there.
The pieces are heavy but way more movable then you would first think. Generally if piece is in good condition it goes quick. If cracked you may have a bigger project.
The best foundation to put under the lifted concrete is usually add some sand. I pile it into the gap under the lifted slab. You can usually soft the sand in well by using a garden hose and just blast sand from the side - swishing the sand mud under the slab until full.
Thanks for putting this out here! I was picking mine up and releveling the dirt, but after a year or so they settled again unlevel! This really helps!
if they continued to settle again after leveling them, then this might be an indication of a continuous problem going on under your slab, such as erosion from rain water drainage or a leaking sprinkler pipe and even tree roots that are causing shifting in the soil under your slab(s).
Excellent tutorial, right to the point, simple to follow, I id it on my driveway and it work perfectly, my cost $32, instead of the $650 quote from a company. Thanks.
Before everyone "rips into me", let me tell you where I'm coming from. I'm a licensed general contractor for over 30 years so I do know a few things.While I applaud his ingenuity, I cant agree with the material choice. Foam compresses, Its as simple as that.That section of sidewalk probably weighs about 500#. Also, you have to look at why the sidewalk sank in the 1st place. Improper compaction of the soil beneath or something else? Has it stopped sinking?
Foundation repair specialists would never repair with foam. They will either use a non-expansive grout or a cement/sand slurry mix.
I hope this works, but I think this guy will be making another video in a few years about fixing a sunken sidewalk again.
contractor since 85, i agree. if he has no traffic , it might be fine. If you have a few of us 200#'s walking on it every day and a few years it will be mushed back down. The slurry is the correct way, but for the average homeowner, prying it up (with a bunch of friends, before the beer flows) and packing small stone with a 2x4 underneath, tamping many times from the sides should do the job. the stone will not allow water to collect under the slab to stop the washout from water or water to freeze and heave it.
Agreed as well. All foam products in every application degrade their structural integrity over time (like 5 years, not 100years). From your couch cushions to the insulation in your house. Also, for sure there was an issue with erosion in the first place that needs to be addressed.
I'm NOT knocking your knowledge. I'd appreciate your input.
I had Three Big Foundations Companies (ex aqua guard), to come out last year and give me a quote on raising my walkway (the sinking is closest to my front steps, at 2' away it drops). It's also pulling away from the house, on the side where walkway runs. Clamps couldn't be put on Both sides, like here.
They were All going to use industrial strength spray foam. They would drill the holes and inject it. None of them would give more than 5 years warranty, because they said this has not been around very long, so they couldn't guarantee it past that.
With what some of you guys are saying, about the spray foam compressing, that's probably Why only 5 yr warranty. But their excuse sounded good!!
I understand most companies are doing the industrial foam vs mudjacking.
What do you think about hydraulic concrete, under it??
It would still have to be raised to get it under there, right?
Any advice you can give me, would be much appreciated. Thank you!
I have an opposite problem. My concrete has gaps at the top where it meats my foundation (driveway, stoop, hvac slab) how is this normally addressed and what type of company would I call?
Thanks
@@pattibond2342 What were the quotes and what were their excuses for using foam over something else?
From an engineering standpoint, this is an awesome video but the practical part of me wants you to pour a new pad! This is a great way to solve the problem without having the mis-match issue though so I see the value.
Same here. I feel like it would be less work to bust out that slab an pour a new one.
Pouring a new slab? You'd never get the texture to match...
Also magnitudes more expensive and more work to replace the slab. He has $16 into the foam. If he had to buy the lumber and chains, maybe another $50, but they'll be useful for future projects too.
@@come_on_now Texture is usually created with a push broom. Not hard at all to match.
@@timfischer I disagree. It's $5 at my hardware store for an 80 pound bag of Sakrete for pouring slabs. You might need two or three. A single bottle jack (you need 4) is $25. A single large open mouth C- clamp is $15, and that's all before the chain, hardware or timbers.
Love how you make it so Joe homeowner can do it. Thanks for sharing
Man, that is genius work. I don't even have a house and I am learning a lot with your videos. Thank you.
Good idea for creating a lift. From doing several of these projects, i always go slightly higher than level or where I want the end result as I find things settle and it extends the time I need to come back and chase my tail. Thanks for sharing👍
I don't have a sidewalk to fix, but you just gave me the perfect method to lift a small shed to put in a new crusher run pad and new floor beams! I knew bottle jacks were part of the equation, but fixing 4X4's to the shed and then lifting the 4X4 with chains might be the ticket. I'll run some calculations to make sure I'm not doing something stupid, though. Thanks - love the channel!
If you have not already done it you could consider strand jacks. They have a hole up through the jack through which you can pass a bar. Pass a bar through your 4x4 (or pair of 4x2) then through another 4x4 at right angles that is supported off the ground. Place jack over bar and secure then jack. Safer than bottle jacks that could tip side ways with you working under shed to prop it to do works.
@@johnclements6614 Haven't done it yet, so your suggestion both appreciated and timely! I'd never heard of strand jacks before, so I'm doing some more googling. What I've found so far looks like the cost would be higher than scrapping the old shed and putting in a new one. Any sources you might be able to recommend?
@@spud13x13 I used a strand jack about twenty years ago for testing bolts that had been epoxied into the side of a bridge. I am in the UK and have not been involved in hiring plant since then. I can not find anything locally to my self with a quick google other than a Chinese site selling small strand jacks for about £400. At that price new I would assume! (big assumption) that be able to hire a couple small jacks, hoses and pump (plus oil etc) for $100 for the weekend if you collected and returned them. I think it would be a case of finding plant hire companies near you that hire jacks then phoning them.
The thing about the bottle jacks is you will have to figure out a safe way of doing the work if they tip side ways.
I don't know how small your shed is but have you considered moving it. I moved a shed once by taking up the floor, putting some runners under it and levering it along whilst stood inside. Obviously puts stress on all the joints but the shed lasted another ten years till I built a bigger shed.
interesting approach. having set forms and poured slabs I think it's less work and longer lasting to demo the old slab, set a form and mix several bags of concrete.
I totally agree! You can rent a small electric jackhammer, concrete mixer, and buy concrete for a whole lot less money. Secondly, you don’t end up with those noticeable ugly filled drill holes that never blend in with the surrounding concrete. But it does take some skill to finish a poured concrete slab to make it look nice and the color won’t match the old concrete sidewalk.
Did a similar project a few years back, but went very simple - dug down front and rear trenches along each side, used a 6 ft pry bar to lift and level the sidewalk slab and supported the now lifted corners using several large "locally sourced" sandstones set on crushed gravel (created a pier) and then backfilled under the slab with flowable fill I purchased at the local big box store. All in costs were about $30, and the hand digging/levelling/backfill took me about 2 hours from beginning to end. This is a very precise approach, but I'm not sure on the great stuff foam CBA long-term.
Yeah, I did this with a tamper bar and rock as a fulcrum to raise the pad, a rock to support the pad, and dirt tamped in from the side to fill the void. $0. But hey, UA-cam is all about the next quick fix.
@@bkupron that was my original plan since most of the dirt underneath was red clay but, after looking at the space underneath the slab after levelling, I wasn't sure I could get enough compaction to have confidence that most/all voids were filled - that's why I went with the fill.
What is "flowable fill?" I wouldn't even know what section of the store to look in. 🤷🏽♀️ Thanks for the tips!
@@bkitteh6295 look for "Non-Shrink Construction Grout" at any big-box home improvement store; typically ~20 for 50 lbs which would be sufficient for most jobs. It's a cement based product that flows into voids easier than standard bagged cement mix.
Thanks. I literally just lifted a section of my driveway with a hydraulic jack and tractor jack then concreted under it. I've still got a lot more to do and now that the driveway is supported with concrete, I wanted something else to fill in the gaps.
This is a great fix. I know commercial guys do the same thing,but charge a high price. This is fantastic and easy. Thanks!
How long does this repair last before the foam degrades?
Clamp a timber on the top and as you lift the slabs, clamp it tight to get the top flat, clean the joints out,, then you can either use the foam, or pour free flowing grout to the underside of the slab - shutter the sides to prevent leakage.
Remember to heavily grease the end of the clamps that end up under the slab (best to wrap them in plastic too) and yank then out as the fill sets)
Grout seems like a better long-term solution to me. I would worry about the foam degrading or the air pockets collapsing.
@@N20Joe I'd not use foam unless I cemented up the sides.
I've seen instances where unexplained floor slab subsidence became very easy to explain after foam was used.
There was a trail of foam granules along the narrow gap behind the building that the resident rats had removed to get back inside
Of course they now had a super insulated home.
The clue is in the name of the product "gap filling foam" it's isn't structural, it might well work, but it's not a true ling term solution, the foam will break down over time, it isn't designed to be saturated and encountered temperature extremes, boats fail because the exact same stuff pumped between the skins form the structure and when wet it crumbles
Nice workflow. I think you could do the same thing with shims from the sides with a tile that size.
Great idea! I have the same problem after an armadillo dug a hole under my entrance slab. Going to be a bit of a mission but at least I now know a way to do it, thank you!
I have a garage with 6x6 slabs that make the floor. each slab has sunk in different directions. After watching you do this I think I could take a laser and mark where the top of slabs need to be and hoist them into position. I would pump grout under the slab until it is completely full and give it a few days to cure before releasing the tension off the hoist. I have been looking for a way to do this without demoing the floor and poring all new. After watching your video I clearly see the way to do it. Thanks
I like your technic for lifting the slab. I personally would rather lift a few more inches so I can throw some sand under the slab. Might take a couple tries to get the right height, but better than drilling holes.
Spectacular solution! Well done. Lot of homes could use this treatment.. but, like shirt says: requires "sweat equity"
I just dug-out 12” under my slab and put put a hydraulic jack under it, cranked it up, and blocked it with a few bricks. Worked great.
I learned that you need to raise the concrete first with a support or bracing. Inject the foam, let foam harden for a few days then remove supports. My step is now level with the rest and holding strong for three years. Caulked the gap with silca self level great.
Recommendation: If the slab is "hanging-up" at the 2 end locations (where the suppressed slab butts up against the other slabs) due to jagged "areas" along the faces of the 2 slabs.... get a Circular Saw with a diamond edge blade... and "run" the blade along the gap area between the 2 slabs. The "cutting" from the diamond blade will remove any jagged areas. This will give smooth faces to each of the abutting slabs and will allow them to "slip past" each other.
The gap here is fine, because you will fill this with caulk. If you don't want to fill the full depth, you can fill the void with sand UP to the final 1/2" of the void (as it reaches this surface of the slab).
NOTE: The slabs MUST be able to move.
First paragraph is good, second isn’t correct.
DO NOT USE SAND. Use backer rod when caulking. Sand will contain the moisture and cause issues if it freezes.
The slab does not have to move except on the side connected to the house.
A sidewalk typically is only locked on the house side so it can push away.
If you remove too much material you will cause the sub grade to wash away and this exact problem will happen again. Although by the that time I would just replace the sidewalk.
And this foam will last a year or 2 top and will deteriorate due to the pressure and water.
@@antonioyoutubeaccount5399 I am ONLY recommending placing some sand in the GROOVE between the 2 slabs with sand, in order to FILL THE VOID there... THEN to push backer rod into the upper portion of the groove. The backer rod, along with the caulk, will keep water from migrating into the joint. Because sand is better "graded" than soil, it will NOT retain water unless there is a water source that is "feeding" from underneath. If that is the case, then the slab will move due to frost heave, and the joint is the LEAST of your problems
@@Jaegertiger i COMPLETELY understood WHAT you WERE saying, I will CLARIFY once again THAT sand is a no GO.
Just use bacKER roD, then CAULK over it.
Source:youtube
This is a very nice job. However, once the concrete was drilled and raised, I would have poured concrete slurry into the holes instead of foam, which will degrade and compact over time.
I think someone didn't do too well with math in school :)
There is no way you could pour enough slurry into such little holes. It would have to be so watered down that you just end up with a mess and by the time it dries, has lost a large volume and still needs more added but now has an un-uniform spread to to flow through under the slab. It would be better to just lift the entire ends of the slab above the other one and pour in the regular density concrete mix.
@@stinkycheese804 - You'd make larger holes. They're going to be filled anyway.
Note to those attempting this, one of the problems not encountered in this video (but you might have) is that the edges of the slab may end up beneath the adjacent sections. Due to shifting, the space where the sunken slab was had contracted, so it wasn't possible to simply lift the sunken one. I had to put a masonry blade on my circular saw and carve away enough of the jagged edge so that there was a clean path for the slab to rise through.
I'd also agree with other commenters who advised against drilling through the slab. I never went that route, so I didn't end up with cracks, but let me suggest an easier and cheaper approach. The sidewalk is only a few feet across, so you can probably reach the middle from either side. Shove some concrete pads, gravel, and/or whatever else you have handy into the void. If you absolutely must use foam, you can start with several large chunks (i.e., paving stones and the like) and then add the foam between those. At the very least you'll spend less on foam. Rocks are far cheaper and all-natural.
Also, I can 2nd the video on the concrete caulk. I applied it all over my 100+ years-old property almost 5 years ago now, and it has held up perfectly. I wasn't willing to repave all the areas with old and badly installed concrete. I used it on the curb alongside the driveway, gaps and cracks in the sidewalk, patio, next to steps, etc., and and in all cases it has not lifted out of the cracks, even after lots of rain, intense summers, and even pressure washing the areas at least 3 times since I applied it. I wish I knew what brand I used in case I have another spot that needs some.
Just curious here, but with the amount of work involved with lifting this small walk area wouldn't it be easier to just break up and pour new in this area?
He doesn't need to do all that work anyway, just drill the holes and fill until it's level. The poly expanding will do the lifting for him.
That is the point of the question. Why do all this to use foam? Use concrete after that. Or mortar if you still feel like doing all that drilling
@@bloody_fobbit2758 That's kinda where I was at here... if you're going to jack up the entire slab, why not just hammer in some thin forms and pour fully plasticized concrete?
Plus all the hardware and supplies he bought for the project.
I did this same thing only I drilled a couple extra holes in the slb and screwed in a long cement lag screws (instead of the C-clamp method) to attach 2 pieces of chain to then hooked those to my board in which I used a floor jack to raise the end of the cement slab. Great vid and thanks!
I mixed a bag of cement and made it so it would flow under my sidewalk and poured from each side. Cheap, easy and solid.
Great solution and procedure. An alternative would be to just but out that section that you lifted and pour a new slab. Cost and time this might be cheaper and also better because in a lot of these cases the slab that is being lifted might not be in the best shape.
that was literally my first thought... this seems like so much more work and expense
@@Steve-ec6ed It was his home - new slab wouldn't match and would be an eyesore.
@@heresthething....4685 It wouldn't match like what looks to be the section of new concrete going in right behind him.?
@@mark-kf3md The material in the background was actually for Plan B if the section of concrete he was raising cracked. The video would have been titled “How to pour a new section of sidewalk”. He was prepared.
@@Steve-ec6ed How is this more expense? He literally said he had $16 into the foam. If he already owned chains and lumber that would be the only cost. Otherwise add $50 for supplies that he can later use on other projects (or lifting more slabs).
Absolutely outstanding video. Wow. You explained it SO well that I wouldn't be afraid to try it, and I'm anything but handy. Thank you!!!!!
I’d be concerned about longevity. Foam breaks down. I
I like how you raised it. If you could pour some kind of concrete into the holes or just excavate more on the sides and fill under with gravel.
When my father and I did something like this at his cottage we cut 4" holes into the slab using a concrete hole saw and poured in small-aggregate ready mix concrete with added plasticizer. We ensured it was well distributed and compacted by using a concrete vibrator that was also fed into those holes... you'd think you'd filled the void and then the vibrator would just cause it to disappear so in went more concrete. I think we left the support structure up for a week to allow the concrete plenty of time to cure before taking the weight of the slab.
Good idea. A new slab would look obvious. The natural look makes everything look like there never was a problem in the beginning.
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Clever. Only a little bit more expensive than ripping out that section and a lot more work with a dubious result. Other than that, brillant. Perfect idea for UA-cam DIYers afraid of working with concrete.
I loved the apparatus that was created to raise up the slab in the video. However I guess the slab was only worth about $5 as opposed to the value of the equipment and materials used being maybe $200. Surely just lifting the slab manually and putting an extra layer of sand underneath would have been simpler?
I knew it wouldn't take long to find someone with some common sense. I would have been done before he drilled his holes.
Rube Goldberg solution
I thought he mentioned at the beginning that the brick was sitting on the same slab he was leveling. If that's the case, you couldn't just lift it out of the way to add more material under it without replacing all the brick.
@@12x2richter just watch the video again. Don't over think it this time.
Have fun trying to lift the slab.
Most of the problems I see are slabs getting lifted by roots. Sunken slabs are rare and make me worried there's a water issue underneath. Would love to see the easy fix for lowering a slab lifted by roots.
Put a mole in your yard it'll sink
Get 2 cans of spray foam... apply to the base of the tree. Cut the tree down. Remove the lifted slabs... grind the stump and the roots... wait a year pack the area and re-pour as needed.
All sarcasm aside I also wonder if spray foam can overcome an underground water flow issue. It was a great video. Nice use of mechanical advantage but I was wondering how you get spray foam off a c-clamp because basically nothing will get it off my hands
@@timnor4803 Once spray foam is dry, it will rub off of most smooth surfaces. However, if you do like I’ve done, spray foam will never come out of brand new shoes that happen to get a random drop on them!
@@timnor4803 acetone is the solvent for not cured foam. Try soaking your tools in some acetone.
Instead of all this, just lift the slab out, compact gravel below it & place the slab back again
What you are doing is too complicated & not required for a DIYer
Great video! Nice to know that anyone can do this by themself without having to pay and arm and a leg to a contractor.
Trevor, good point! I would haveJust lifted it up and put a couple of blocks underneath to level it and then, add a length of tubing to the can of foam and insert it into the middle!
Must be an engineer. I never seen anybody make such a complicated project of a simple repair. But I did watch for a minute like a dumbass so mission accomplished.
I like the use of the word "Dumbass" as I feel it is appropriate.
The foam may be sturdy, but it has give and will move more than a solid object. I would suggest a treated wood block or a brick or rock on the sides.
I would think he could raise it with the jack n c-clamps then pack with rocks using a piece of wood or the pry bar. Then fill the remaining void with foam. I need to lift my patio porch due to stress cracks which have opened up enough for rain water to penetrate and wash away some dirt below the slab. I only recently learned this is what was happening thanks to these type of videos.
Nice well done video. You can save money and time by just wrapping the chains around the beams. No need to buy and install the J-Bolts. I did a similar repair. I did not use great stuff, I would be concerned how it would last over time. I got High density foam sheets and cut to size and slipped in from the sides. This also removes the requirement to drill the holes.
Do you remember what kind of foam you used? I know you said high density, but is there a specific kind?
@@kristfur ua-cam.com/video/31uSPxKmBFA/v-deo.html
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FOUR YEARS AGO, HAD THE SAME PROBLEM. GOT MY PRY BAR, PRYED UP THE SLAB, AND STUFFED SOME GRAVEL UNDER. STILL HOLDING TODAY.
DIDN'T SPEND A LOT OF MONEY ON JACKS, CHAINS, AND 4X4 LUMBER.
I applaud your technique. I usually just repour new concrete, but that's a pretty slick hack. I'm curious to know if it still holds true in place five or ten years later.
The only problem is over time the foam will degrade and you will be back to where you started from
Everything degrades over time. That's like saying bananas will brown eventually after picked. It's all about how much time.
Great process for doing this - I have something similar with my sidewalk and this might be the ticket to fix it w/o hiring someone :)
Lifting up a small concrete slab can be done in a million different ways; one must simply be commonsense-cautious to not crack it. Then, once raised, it's not too difficult to dig a bit to gain access to the underside, from the sides, and then manually fill the cavity with gravel or similar fill. The advantage of the process that I'm describing here is that it does not require procurement of all the items being shown here (wood, jacks, chains, hardware, hammer drill, drill bit, and two cans of foam).
I got a long pry bar. Took up each corner and put some wood wedges to hold it in place. Then used DGA to shove under. Next time I will try the spray foam idea though.
What is DGA?
Note for the cost of renting a rotary hammer drill, you can purchase a cheap one from Harbor Freight. Yes the professional ones are a beast and will last for years, but I grabbed a corded 8Amp Bauer for me $67. I'm sure I'll die randomly but I've gotten 7-8 projects out of it and even resorted to doing things I normally wouldn't abuse a drill for (like digging holes and churning compost with auger bits).
Very cool! Please do a follow up in one year.
For sure 👍