How to Pour a Monolithic Concrete Slab | the Skills and Concrete Finishing Tools you Need to Succeed
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- Опубліковано 11 лип 2024
- Whether you’re interested in building a DIY concrete slab for a shed, or you're pouring a concrete foundation for a house and hiring concrete slab foundation contractors, this video will get you prepared to build the best concrete slab foundation you possibly can! I’m gonna walk you through our concrete day on the wedding barn project and explain what’s happening, show you the concrete tools we’re using, and let you in on a few critical details that will hopefully help you succeed on your project. Thanks for watching!
There’s nothing more exciting than getting your project out of the ground. And today is that day! We’re pouring a Monolithic Concrete Slab Foundation, for an 8000 sq ft timber-framed wedding barn event center. By this point, you should have already completed all your prep work. You’ve installed your wood or steel form boards around the foundation perimeter. You’ve got your underslab plumbing and electrical installed and inspected. You’ve got your gravel, vapor barrier plastic sheeting, insulation, rebar and any floor drains and radon gas vents piped.
But chances are that you’ve still got a few loose ends to tie up! For instance, I’m adding a copper ground wire that ties into all the steel reinforcement embedded in the concrete. We’ve got a lot of bedrock around this site, and probably won’t be able to drive ground rods a full 8 feet deep, so having that extra grounding force will help big time. Fortunately, we poured the concrete footings first with a stiffer concrete mix so that it would support its own weight a little better and not put so much force on the steel formwork going around the perimeter. In which case, I was able to feed the #8 ground wire down through the concrete footing mix and out underneath the form to connect to the future electrical panel and ground rods. The next load going down is a wetter 4.5” slump that’s gonna be much easier to spread around and trowel finish.
Concrete crews like to start at the crack of dawn.
Concrete - Make sure you know how to calculate how much concrete you need. Concrete is measured in cubic yards. A yard is 3 ft long x 3 ft wide x 3 ft high. That’s 27 cubic feet.
It gets a little tricky in the turn down footing of a monolithic slab. You’ll need to measure the cross-section below the slab floor height and multiply by the lineal feet of the footing to get the cubic feet.
Pump Truck (if you have the space). A pump truck usually costs $175/hr on top of the concrete material costs
Mud Boots
Gloves
Hammer - it's important to vibrate the exposed edges of concrete along your formwork to encourage the concrete to settle into the voids and give you a completely solid wall with no pockets, or honeycombs.
Come-Along - (amzn.to/3w9IEoa) a concrete rake, called the come along is an invaluable tool. Push and pull concrete easily and get it flat as you rake it around from high spots to low spots. It also has a hook on one side that can be used to pick up the reinforcement wire so that it’s properly suspended within the top 1” of the concrete.
Mag Trowel (amzn.to/350mBEJ) - stiff magnesium float that pushes down gravel and bring the creamy cement/sand mix to the top to get a buttery smooth surface that’s easy to finish.
Laser Level (self-leveling) amzn.to/3v6R0M0
Screed - wood or aluminum - straight board that flattens concrete in between two known level points. (amzn.to/3pBPNLt)
The Vibrating screed -(amzn.to/3ipOGx3) is a tool that will save you a ton of time and energy kneeling down in the concrete with a regular wood or aluminum screed.
Bull Float - (amzn.to/2Sowt8v - 48" head + handles amzn.to/3wktpZy) one man can use this tool to start the rough finishing process. The bull float is a thick and rigid magnesium float that effectively pushes down the rock aggregate beneath the surface and brings the creamy cement and sand slurry to the surface to make it easy to get a slick finish.
Edger - (amzn.to/3goVPuG) creates a roundover edge that looks really good and won’t chip off like a sharp, squared-up corner after the formwork is removed.
Finishing trowels - (amzn.to/3zc1I7f) thin metal trowels are flexible and allow you to get a really smooth finish once the concrete has set up and feels like wet putty.
Finishing machine - (amzn.to/3isfLj0) power trowels are a critical tool on a large slab foundation
Control joint saw - (amzn.to/3gkOPiB) Two things are guaranteed with concrete: it WILL get hard; and eventually, it WILL CRACK. Control joints are a 1” deep cut in the slab floor that encourage those cracks to happen where you want them. You end up with less lightning-pattern spider cracking, and more decorative lines, or pattern cuts. The American Concrete Institute recommends spacing control joints no more than 3 times the thickness, in feet. Here we have a 4” thick slab, so when we multiply 4” x 3, we get a control joint spacing of 12 feet. - Навчання та стиль
Great video. Very informative with good detail. Grounding through the slab...yep learned something new. Do you happen to know of a quality contractor that operates in Granville county? Will be looking to have a block crawlspace underway in the coming weeks. Thanks for sharing.
Glad the video was helpful! What type of contractor are you looking for? Block mason or general contractor?
@@HeirloomBuildersLooking for a reliable block Mason.
Shot me an email and I’ll send you a lead. Logan@heirloombuilders.com
thanks for good & concise detail of your slab process.
Thank you. This helped a lot.
Using a vibration tool is definitely a good idea to avoid getting any air pockets/holes along concrete edges etc.
Vibration tool?
Great information
Ty for video
Slump 4. Quite a familiar monolithic slab indeed. Awesome video thanks for sharing.
You bet. Thanks for watching!
Very informative!
Milton Brown glad you liked it. Make sure to subscribe for more informational videos. Welcome aboard!
Great channel and really informative information. Is it at all possible to show/list measurements etc in metric? It would be really helpful for people that only use metric these days. 😊
Really glad to find this thread....I'm building a 4200 square foot timber frame barn/shop/garage down east in NC, and concrete is only a little less mysterious to me than electricity. Your event barn monolithic slab layout is very similar to mine; continous perimeter turndown, supporting 36 anchored timber posts w large integral interior post footings.
Have a question about control joints....spacing issues....do you AVOID the interior posts?....I have significant footings under 16 of them. I've have seen ACI commentary about trying to line up control joints with lines of "columns" in the structure with control joints. Since I have 2'x2'x12" interior reinforced footings, it seems unlikely I will "encourage" the inevitable cracks to occur along that sort of line. It is anything but the thinnest part of 4" slab. Ditto exterior posts, since turn down is 18 inches on the sides and 24 inches on the ends, all rebar reinforced. Additionally, wire mesh is used throughout slab. Doesn't that interfere with function of control joints?
Sorry about the Newb level of questions, but I'm only building this heirloom once....I'd like it to have the best chances of it achieving the 150 year age of the family farmhouse it will sit next to. Pouring 100 yards in my barn....a lot of "essential to have" techniques on your build are pricelessly valuable to me. Your production and audience targeting were extremely good, watchable and useful.
why did you not put the vapor Barrier also under the footers?
Are there any regulations about building a garage slab over an existing sewer line running through the property. For instance adding a garage slab spanning the width of a back yard with the sewer line running out the back of an existing home out under the slab and garage.
Logan: followed your series with interest throughout. Off topic, but wonder if you can comment on detail items in the Alamance wedding barn, particularly the cupola, and the many accessories need to "finish" a good TF barn "look". I've just finished my 60 x 70 slab, and frame is on it's way down here in New Bern. I'm looking for creative ways to provide passive ventilation and cooling....and I'm always looking for closer sources of barn-shop-garage ideas compatible with timber frame designs. There are a lot of finishing touches I can't just DIY.
Direct question of the day: does the barn have a hot or cold roof design? Why and how? Might be a good topic if it's not already covered, along with environmental control topics in general for "open door" barn venues....whether for weddings, or shop/garage/barn spaces.
Thanks, Bill Holton
Good to hear from you, Bill. Glad to hear your project is moving along. We put together a short video about the cupolas and their passive cooling and ventilation capacity. I designed the barn to have casement windows to catch the breezes and force air through the building in the summer months. That will probably go just as far as the cupolas in the effect they have on passive cooling. The barn also has two 5 ton hvac units to provide “spot” heat and cooling To the main enclosed building, and mini splits to condition the air in the bathrooms and catering room.
@@HeirloomBuilders My bad...found the cupola video after I emailed. Does the barn have a hot or cold roof?
Thanks for the details; still searching for information on actually engineering of cupola placement/size, window or louvre size and control. The "rules of thumb" available online in many places are nice, but I see no real overall analysis of building size, volume, CFM or thermal analysis sort of guidelines. If I'm going to put holes in my $60k roof envelope, I don't want to just go with what looks proportionally pleasant, etc. I do favor the cupolas for style over more modern vent solutions. Also favor transom/chancery windows over louvres (for the ambient light). Thinking about a discreetly solar powered fan system near ridgeline. I will hav a mini-split for my 500 sf shop corner area "as required", but the rest of the building will be as low powered/passive as possible. It is mostly intended for vehicle work/storage down, wood storage in the lofts.
Would you guys be interested in a raising (traditional timber frame joinery) supervised by frame maker in February time frame? There is potentially more than just the raising in the offing.
U know your business well. I have met a fair amount who don't put the effort and care.
Alex modern its a lot more fun to care, and take pride in the work we do.
I would of thought for a slab of this size that the steel mesh would need to be of a bigger gauge and spacers used to create the required space between the membrane and the top of the concrete slab.
.
No steel mesh is required on this project. We’ve been using fiber reinforcement on smaller projects instead of the welded wire mesh
So rebar is not necessary if you're using mesh? I am almost ready to pour a wood working shop slab 30x42 ...would you use rebar or mesh in that?
hugh jasole good question. Rebar is always better than mesh, but mesh is used on most residential slabs. Even then, no reinforcement is REQUIRED on residential slabs. But depending on your equipment/vehicles weight in your shop, you’d probably not regret the additional cost of rebar.
@@HeirloomBuilders Okay...thank you....most of the tools will weigh between 200-500 pounds...rebar it is then. I was hoping to save a buck but rather it be done right.
@@hughjasole9336 i hear that! I felt the same when I built my house.
Is there no need to place spacers under rebar mesh,to keep mesh an inch below vapor sheet, also horizontal in the concrete.
Spacers are great with #4 rebar, since the rebar can hold the weight of a person and the spacing allows room for foot traffic. but the re-mesh bends too much and makes it dangerous to walk on. It’s much easier to just pull the mesh up to where you want it as you place the concrete
@@HeirloomBuilders Thanks, Great job 👍🏻
Vapor barrier is insulating the slab from ground, so how does UFER wire work?
J D great question. We mostly tie our UFER into the footings, which don’t have a vapor barrier. This monolithic slab contacts the ground on the bottom and exterior side (since the vapor barrier only extends to the interior vertical side of the turn down footing.) in other words, there is still ground contact and re-mesh is continuous and tied into footing. That would be a great question for an electrical engineer
@@HeirloomBuilders Concrete is not a conductor, and rebar is not an acceptable ground. You need a ground rod or ground plate deep in the dirt to meet electrical code.
@@atodaso1668 you’re right that concrete is not a conductor, but wrong that rebar is not an acceptable conductor. Check the code book, it’s called a “ufer” and required in a lot of places. We tie that wire to a ground rod like you mention
@@HeirloomBuilders Its not code here in Canada. I don't see what a piece of #6 copper twisted loosely around a piece of floating steel suspended in the slab is going to add to the ground system. The only thing that comes close is I had to bond rebar with compression crimps. But that was for a steel structure in a highly explosive part of a coal export yard.
Grounded to the steel in a floating slab? That is not an electrical ground. You need a ground rod or a ground plate for electrical grounding.
Didn't even use rebar chairs. Pull up technique is so dodgey
Johnson Rocson those wire chairs are hard to see.
Really glad to find this thread....I'm building a 4200 square foot timber frame barn/shop/garage down east in NC, and concrete is only a little less mysterious to me than electricity. Your event barn monolithic slab layout is very similar to mine; continous perimeter turndown, supporting 36 anchored timber posts w large integral interior post footings.
Have a question about control joints....spacing issues....do you AVOID the interior posts?....I have significant footings under 16 of them. I've have seen ACI commentary about trying to line up control joints with lines of "columns" in the structure with control joints. Since I have 2'x2'x12" interior reinforced footings, it seems unlikely I will "encourage" the inevitable cracks to occur along that sort of line. It is anything but the thinnest part of 4" slab. Ditto exterior posts, since turn down is 18 inches on the sides and 24 inches on the ends, all rebar reinforced. Additionally, wire mesh is used throughout slab. Doesn't that interfere with function of control joints?
Sorry about the Newb level of questions, but I'm only building this heirloom once....I'd like it to have the best chances of it achieving the 150 year age of the family farmhouse it will sit next to. Pouring 100 yards in my barn....a lot of "essential to have" techniques on your build are pricelessly valuable to me. Your production and audience targeting were extremely good, watchable and useful.
Those are all good questions! We made a grid of control joints with the interior thickened footers in the middle of those grids, for the same reason you mention. Concrete will always find the thinnest or weakest place to form a crack, and those integral footers are not the place!
The reinforcement mesh will not interfere with the cracking or stop carjacking in any way. It only serves to hold the concrete together (and keep it in the same plane).
Thanks for the feedback as well. I’m glad you found the video helpful!