I’m getting ready to paint my basement, but the previous owner had all these areas filled with shitty fiberglass And I need it to look better before painting. This video is exactly what I was looking for thank you!
I precut most of mine on a table saw . 2" XPS , sprayed the band then apply xps then seal gaps with the same foam spray. Then I repeated so had total of 4" of XPS. Then I covered the foam board with roxul (rockwool) for a fire barrier. The total thickness will also insulate the top of the foundation.
Great video overall, one heads up, XPS or Owens Corning Foamular never loses its insulation R-Value (resistance to heat flow) in any situation. The XPS is formed in a negative atmosphere process creating millions of micro air pockets where the EPS (coffee cup white material) is bonded small foam pieces together. Both work very well in dry applications, EPS white coffee cup foam loses R-Insulation Value in moist situations like behind siding or below external grade on foundations because it allows water to saturate it. Both should be covered with fiberglass non-paper faced or some other non combustible material if left exposed to the living space per building code, foam is highly combustible. Finally, the wrong type of spray foam will each the insulation boards, look for spray foam that is XPS/EPS compatible, Owens Corning makes one. Take care, hint hint, a manufacturer of foam board lol.
O.k. I am seeing a lot of guys suggesting this method. It looks good and reduces air leakage. BUT, I was always told that wood has to breath or it will rot. Fiberglass will let the wood breath and the board will not. So isnt it better to sacrifice the energy efficiency and leave it un-insulated. I live in a 52 year old house, with no insulation on the headers,, the wood is solid. I worry sealing the moisture into the wood would have rotted them out Am I wrong?
I’d check the insulation/vapor barrier on the exterior of your house…but in terms of condensation/moisture on your rim joist (inside the house), the reason it occurs is due to warm/humid air interacting with a cold wood rim joist. Spray foam insulation eliminates this issue entirely because it creates a vapor barrier. But you have to pull the moisture out of the wood first.
You should mention for crawlspaces or unfinished basements that the foam board needs a 30 minute fire barrier by code due to toxic fumes created during burning of the foam in case of a fire.
The other important part is to Insulate the foundation top within the rim joist. Typically it sticks out as far as 4 inches and concrete is poor insulator. Nice work on the foam board.
Thank you. Should 2" foil faced polyiso board be used? How does it compare to the other types of foam board? The space is going to be finished with drywall. Can batt insulation go on top of the polyiso after it's been picture framed with Great Stuff's Gaps and Cracks? Should penetrations be caulked first or can the spray foam be used?
Polyiso is a poor choice in cold climates as it loses significant r value when cold. www.greenbuildingadvisor.com/article/cold-weather-performance-of-polyisocyanurate XPS is a better choice in cold climates.
@@richcombs4805 Hi Rich, Polyiso has great performance in warm weather and is far more fire resistant than other foam boards. All good. But in cold climates, it's R value goes down considerably. Lots of online sources referencing this. So.... I wouldn't use it on exterior walls, basement walls or RiM joists at least in cold climates. I happen to be in northern NH where my interior basement wall is often in the 30's at the top of the wall and around 45-50 at the base which is at or below the frost line. Outside temps regularly go below zero in the winter, sometimes as low as minus 20-25! I have combined XPS and Polyiso where I've used XPS on a cold surface and then glued the Polyiso onto it on the warmer side where i wanted to build up the insulation/R value. In that manner it was in a warmer location and I could benefit from it's higher R value when not subjected to cold temps.
I have a 2ft tall crawl space, poured slab concrete flooring. It will be a bear to work in there but it has to happen. This addition was added as a '3 seasons' room and has zero insulation. But previous owners remove interior separation to add the room full-time to the home. That being said, top of my CMU/cinder blocks are open faced. Should I shove batt inside and seal the top with foamboard in lieu of the wooden board you have running across the top of yours? Do you think doing 2 square cutouts per rim joist would be worth the extra work (Wisconsin winters)? Great video, thanks!
That’s called flash and batt…yes you can. Not sure what good that would do, really…unless you’re finishing off the cavity with drywall/plywood, etc. The more you d*ck around with fiberglass insulation, the more it loses its R value.
Ok, dumb question: the heat comes from in the house during the winter but then the heat comes from outside during the summer. So if I'm planning on doing to my rim joists this way in the future, which way should I orient the shine side?
Yes, but you may have test a piece of foam-board with the spray foam to make sure it does not dissolve with the extra spray foam. If it does you can try a denser foam-board or different brand of spray foam.
I was going to put my fiberglass back over the r-10 (for additional r value -I'm in Ohio) and then put1/2" fire rated drywall squares over that inside of the joist. Does that meet code? I don't want to finish my ceiling...
I wanted to cover the boards with Rockwool, but unfortunately the area is only big enough for the foam board and nothing to strap the Rockwool too. Any suggestions or should I leave as-is?
How does the basement framing interact with the rim joist insulation. Do I need to extend the wall vapour barrier up into the joist. Or will this create a double vapour barrier situation.
Just vapor barrier the wall up to sill plate. If finishing the ceiling. Install vapor barrier on bottom of floors joists but leave 1" gap where barrier meets rim joist for air flow. The rim joist is usually a pretty thin area compared to the rest of walls so it needs more attention.
I’m going to insulate the rim joists I have access to in my crawlspace with concrete floors/walls. Since the rest of my basement is finished….one would assume those rim joists are insulated properly…🤔
If the 2" of rigid Insulation is cut at least 1/2 an inch smaller than your Rim Joist and Floor Joists sealing the Rigid Insulation with Foam is the best option. IF you are using the correct foam (Closed) that is your vapor barrier. No need for any other Vapor barriers. Fill the rim joist to the max without Compressing the Batt Insulation. People always compress the edges. That is Human nature. LOL. Paper backed insulation while the standard many years ago is an invite to mold. So plastic would be the only option IF you use only Fibreglass Batts. You must seal the plastic with an Acoustic Sealer though (Around the Floor Joists and the Floor itself then attaching the cut plastic to the Acoustic Sealer) Don't forget to add the Sealer to the Bottom plate also! Between the floor and your Bottom Plate. There is no guarantee that your floor is level.
is it okay to primer to rim joists? looking to use something with mold inhibitor for extra protection, Just want to make sure im not doing more harm than good.
Did you add those 2x6 blocks within the joists for the purposes of the rigid foam? I assume you did this to make a relatively flush vertical surface that a square of foam would fit in nicely, plus no voids on the sides, and avoiding using huge amounts of spray foam. Close?
It does work better for the foam. But it's actually to reinforce the i-joist webbings at the ends. the blocks give it more structure for nailing to rim joists and also keep the i joists from twisting.
@@D.I.Y._All-in-One If using XPS board (ie Foamular) and mineral batt there should be no air gap inbetween. Goal of insulation is to remove any cold spots which can develop from such air gaps. Also apply a poly sheet (vapour barrier) after the batt is installed and seal/tape the sheet to the joists.
Hello. If it's insulated properly there should not be any moisture build-up regardless which one used. That being said If you wanna use EPS it does have better insulation properties it just costs more.
Do you recommend spraying some of the foam onto the face of the joist itself then pushing the board in place, then foaming around it? I'm a bit confused about the moisture barrier part of this. I understand wood absorbs water, and that there is a potential of mold and wood rot, but given the fact that their is even a slither of space between the joist and the board aren't you creating an area where water can accumulate and result in these issues? I am not being a critic here. I am asking because I have to tackle this on my own home and want to do it myself with a bit of piece of mind. Thanks.
I had the same argument, finally understand why it doesn't matter now. The first point is to understand is that we, people, are creating an issue by having a warm room. If the warm air leaves and touches cold joists, it condenses. If warm air never leaves it won't cause a problem. So the foam board and foam spray is NOT to stop air from outside coming in, but it's to stop air from inside leaving (it does both but stopping warm air leaving is more important). This is a nuanced point but very important because cold wood + warm air causes the air to dump its moisture.
In addition to the spray foam, I use and adhesive caulk to seal any gaps first, and seal the front side of the foam board to the rim joist.
My dude, you need to make a Playlist for this build! Great info. Very much appreciated
I’m getting ready to paint my basement, but the previous owner had all these areas filled with shitty fiberglass And I need it to look better before painting. This video is exactly what I was looking for thank you!
Mine as well. But tbh building science has came a really long way in the last 20 years so its hard to blame them
I precut most of mine on a table saw . 2" XPS , sprayed the band then apply xps then seal gaps with the same foam spray.
Then I repeated so had total of 4" of XPS. Then I covered the foam board with roxul (rockwool) for a fire barrier.
The total thickness will also insulate the top of the foundation.
Nice.
I wondered about doing it this way as well. Spraying some foam in first then pushing the board into place. What spray foam did you use?
@@youtoldharpotobeatme5023 Great Stuff
@@HighGear7445 The fire proof one or the regular one?
@@youtoldharpotobeatme5023 Regular foam . For fireproofing the best thing to use is mineral wool to cover the foam panel completely(Roxul).
Great video overall, one heads up, XPS or Owens Corning Foamular never loses its insulation R-Value (resistance to heat flow) in any situation. The XPS is formed in a negative atmosphere process creating millions of micro air pockets where the EPS (coffee cup white material) is bonded small foam pieces together. Both work very well in dry applications, EPS white coffee cup foam loses R-Insulation Value in moist situations like behind siding or below external grade on foundations because it allows water to saturate it. Both should be covered with fiberglass non-paper faced or some other non combustible material if left exposed to the living space per building code, foam is highly combustible. Finally, the wrong type of spray foam will each the insulation boards, look for spray foam that is XPS/EPS compatible, Owens Corning makes one. Take care, hint hint, a manufacturer of foam board lol.
It's worth the extra $ for sure and it's easy to work with.
Having a basement would you still fill in between joists with fiberglass batt insulation. Thanks for video.
O.k. I am seeing a lot of guys suggesting this method. It looks good and reduces air leakage. BUT, I was always told that wood has to breath or it will rot. Fiberglass will let the wood breath and the board will not. So isnt it better to sacrifice the energy efficiency and leave it un-insulated. I live in a 52 year old house, with no insulation on the headers,, the wood is solid. I worry sealing the moisture into the wood would have rotted them out Am I wrong?
I’m kind of in the same boat. If it’s not broke, don’t fix it 👍
Could you imagine having a rotted out rim joist?!! I’d rather have cold feet bro
I’d check the insulation/vapor barrier on the exterior of your house…but in terms of condensation/moisture on your rim joist (inside the house), the reason it occurs is due to warm/humid air interacting with a cold wood rim joist.
Spray foam insulation eliminates this issue entirely because it creates a vapor barrier. But you have to pull the moisture out of the wood first.
You should mention for crawlspaces or unfinished basements that the foam board needs a 30 minute fire barrier by code due to toxic fumes created during burning of the foam in case of a fire.
Unless using a thermasheath style
The other important part is to Insulate the foundation top within the rim joist. Typically it sticks out as far as 4 inches and concrete is poor insulator. Nice work on the foam board.
This is great if you don't have a lot of obstructions near the rim joists.
Battling that right now.
Shouldn't the foil side be towards the inside?
Would it be helpful to spray borate termite treatment on the rim joist and sill plate prior to doing this job?
Great info. Thanks a lot getting ready to do mine
Liked your video. /subscribed also. Question, approximately , how many boards did it take to do your rim joists. Thanks
If you cut the end of the foam board not perfectly straight, would the spray foam fill the extra gap ok?
Yes
Yes…it’s called expandable foam because it expands ;)
Thank you. Should 2" foil faced polyiso board be used? How does it compare to the other types of foam board? The space is going to be finished with drywall. Can batt insulation go on top of the polyiso after it's been picture framed with Great Stuff's Gaps and Cracks? Should penetrations be caulked first or can the spray foam be used?
Polyiso is a poor choice in cold climates as it loses significant r value when cold. www.greenbuildingadvisor.com/article/cold-weather-performance-of-polyisocyanurate XPS is a better choice in cold climates.
@@BobPritchard are you referring to indoor or outdoor applications?
@@richcombs4805 Hi Rich, Polyiso has great performance in warm weather and is far more fire resistant than other foam boards. All good. But in cold climates, it's R value goes down considerably. Lots of online sources referencing this. So.... I wouldn't use it on exterior walls, basement walls or RiM joists at least in cold climates. I happen to be in northern NH where my interior basement wall is often in the 30's at the top of the wall and around 45-50 at the base which is at or below the frost line. Outside temps regularly go below zero in the winter, sometimes as low as minus 20-25! I have combined XPS and Polyiso where I've used XPS on a cold surface and then glued the Polyiso onto it on the warmer side where i wanted to build up the insulation/R value. In that manner it was in a warmer location and I could benefit from it's higher R value when not subjected to cold temps.
I need to do this!!!
Thanks I’m going to do this
I have a 2ft tall crawl space, poured slab concrete flooring. It will be a bear to work in there but it has to happen. This addition was added as a '3 seasons' room and has zero insulation. But previous owners remove interior separation to add the room full-time to the home.
That being said, top of my CMU/cinder blocks are open faced. Should I shove batt inside and seal the top with foamboard in lieu of the wooden board you have running across the top of yours?
Do you think doing 2 square cutouts per rim joist would be worth the extra work (Wisconsin winters)?
Great video, thanks!
Great! Finally someone covered this topic. Can I add insulation batt on top of this?
That’s called flash and batt…yes you can. Not sure what good that would do, really…unless you’re finishing off the cavity with drywall/plywood, etc.
The more you d*ck around with fiberglass insulation, the more it loses its R value.
The shiny foil side should face towards the heat. It's a radiant heat reflector.
Ok, dumb question: the heat comes from in the house during the winter but then the heat comes from outside during the summer. So if I'm planning on doing to my rim joists this way in the future, which way should I orient the shine side?
@@m3coupe4me the foil side should face the interior
@@m3coupe4me Foil should face at least a 1" air gap, in this case that'd be facing into the basement.
@@m3coupe4meyou’ll need to flip them every season. 😂
Looks good! Way to go!
My I-beams don’t have those pieces of 2x8 to fill that gap, can I just spray with foam?
Yes, but you may have test a piece of foam-board with the spray foam to make sure it does not dissolve with the extra spray foam. If it does you can try a denser foam-board or different brand of spray foam.
I was going to put my fiberglass back over the r-10 (for additional r value -I'm in Ohio) and then put1/2" fire rated drywall squares over that inside of the joist. Does that meet code? I don't want to finish my ceiling...
I wanted to cover the boards with Rockwool, but unfortunately the area is only big enough for the foam board and nothing to strap the Rockwool too. Any suggestions or should I leave as-is?
Plastic and staples should hold the Rockwool. (FTR: Plastic on the inside of the room.)
How does the basement framing interact with the rim joist insulation. Do I need to extend the wall vapour barrier up into the joist. Or will this create a double vapour barrier situation.
Just vapor barrier the wall up to sill plate. If finishing the ceiling. Install vapor barrier on bottom of floors joists but leave 1" gap where barrier meets rim joist for air flow. The rim joist is usually a pretty thin area compared to the rest of walls so it needs more attention.
I’m going to insulate the rim joists I have access to in my crawlspace with concrete floors/walls. Since the rest of my basement is finished….one would assume those rim joists are insulated properly…🤔
Would you suggest after adding the foam boards to the rim joist to use batt insulation in the floor joists?
That will work. But use a vapor barrier though either paper backed insulation or seal with plastic after installing insulation.
If the 2" of rigid Insulation is cut at least 1/2 an inch smaller than your Rim Joist and Floor Joists sealing the Rigid Insulation with Foam is the best option. IF you are using the correct foam (Closed) that is your vapor barrier. No need for any other Vapor barriers. Fill the rim joist to the max without Compressing the Batt Insulation. People always compress the edges. That is Human nature. LOL.
Paper backed insulation while the standard many years ago is an invite to mold. So plastic would be the only option IF you use only Fibreglass Batts. You must seal the plastic with an Acoustic Sealer though (Around the Floor Joists and the Floor itself then attaching the cut plastic to the Acoustic Sealer) Don't forget to add the Sealer to the Bottom plate also! Between the floor and your Bottom Plate. There is no guarantee that your floor is level.
is it okay to primer to rim joists? looking to use something with mold inhibitor for extra protection, Just want to make sure im not doing more harm than good.
Did you add those 2x6 blocks within the joists for the purposes of the rigid foam? I assume you did this to make a relatively flush vertical surface that a square of foam would fit in nicely, plus no voids on the sides, and avoiding using huge amounts of spray foam. Close?
It does work better for the foam. But it's actually to reinforce the i-joist webbings at the ends. the blocks give it more structure for nailing to rim joists and also keep the i joists from twisting.
@@D.I.Y._All-in-One 😆 Or just use 2x12s for joists.
Can you paint this? I’m painting my basement ceiling back and don’t want pink showing.
Yes but might need to use primer first.
Can you use bat insulation in the space after using your form board-spray foam process in order to increase insulating properties?
Yes. But leave a small 1" gap between bat and foam to allow air flow between the two.
@@D.I.Y._All-in-One If using XPS board (ie Foamular) and mineral batt there should be no air gap inbetween. Goal of insulation is to remove any cold spots which can develop from such air gaps. Also apply a poly sheet (vapour barrier) after the batt is installed and seal/tape the sheet to the joists.
Could you double up the foam board for twice the R value?
Yep
How does that board handle fires?
Really helpful - thanks!
I've heard that XPS foam board holds the moisture between the joist an board causing mold was told to use EPS board instead.
Hello. If it's insulated properly there should not be any moisture build-up regardless which one used. That being said If you wanna use EPS it does have better insulation properties it just costs more.
What about termites?
You have to use spray foam formulated for use with foam board, or it will eat the foam board over time
What brand will you suggest instead?
Thanks!
What about fire block foam?
Should work fine
Losing 10 percent of 7.5 r value is still better the 6 that first lose the t value
You stiil have air comming where plate sits on concrite.
There is a sill plate gasket on mine
👍👍🔥
termite inspections ?
They’d be handled the same way as a fully finished basement 😊
Lol. Used a level and still had a wonky cut haha
The foamular now end 2022 costs $46, literally a 300% increase.
Inflation for you.
In my area, a 2" thick 4x8 sheet costs $55. If you translate this to a 1.5" thick 2x8 sheet, like what was shown in the video, it would be $21.
had cringed when saw OSB panels...
Do you recommend spraying some of the foam onto the face of the joist itself then pushing the board in place, then foaming around it? I'm a bit confused about the moisture barrier part of this. I understand wood absorbs water, and that there is a potential of mold and wood rot, but given the fact that their is even a slither of space between the joist and the board aren't you creating an area where water can accumulate and result in these issues? I am not being a critic here. I am asking because I have to tackle this on my own home and want to do it myself with a bit of piece of mind. Thanks.
I had the same argument, finally understand why it doesn't matter now. The first point is to understand is that we, people, are creating an issue by having a warm room. If the warm air leaves and touches cold joists, it condenses. If warm air never leaves it won't cause a problem. So the foam board and foam spray is NOT to stop air from outside coming in, but it's to stop air from inside leaving (it does both but stopping warm air leaving is more important). This is a nuanced point but very important because cold wood + warm air causes the air to dump its moisture.
Maybe plastic the inside of each piece to prevent warm air from inside the house from reaching the foam board? Just a thought.