# Will spray foam stick to concrete?



## Leah Frances (Jan 13, 2008)

mikegp said:


> I have seen many people do it, but someone on here made me feel like I'm an idiot for even considering. I have heard a few stories of people having issues. So what's the general concensus? Anyone have personal experience? I'm speaking of the foam-it-green spray specifically. This is a below grade basement that has been sprayed with Radon Seal. It was poured in July of 08. Thanks.


It will stick to just about anything. The better question is whether or not it is the right material for what you want to accomplish.

So, what do you want to accomplish. We need details here.


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## AGWhitehouse (Jul 1, 2011)

It certainly isn't recommended. Try reading the technical sheets looking specifically at the substrate requirements. I'm not familiar with the product you mentioned but the spray foams I have specified have specific moisture content requirements for the substrate material.


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## mikegp (Jul 17, 2011)

Finishing basement. Foam-it-green is closed cell, so would like to use it as insulation and a vapor barrier. It never gets really cold or hot down there, so was thinking of just spraying it about an inch thick if possible to save money. Honestly, I mostly want it for the vapor barrier since I can get away with no insulation down there.


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## Leah Frances (Jan 13, 2008)

mikegp said:


> Finishing basement. Foam-it-green is closed cell, so would like to use it as insulation and a vapor barrier. It never gets really cold or hot down there, so was thinking of just spraying it about an inch thick if possible to save money. Honestly, I mostly want it for the vapor barrier since I can get away with no insulation down there.


Why not just do the vapor barrier?


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## mikegp (Jul 17, 2011)

I don't want to get condensation and mold behind it. There's a lot of controversy about whether or not to put one in a basement. Plus the foam seems like it will seal everything up much better.


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## Red Squirrel (Jun 29, 2009)

Yep should be fine. I had a crawlspace professionally done, walls (cinder block) and ceiling (concrete).


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## mikegp (Jul 17, 2011)

Now that's pretty.


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## AGWhitehouse (Jul 1, 2011)

Now that's a fire hazard...can't do that here in CT without a thermal & ignition barrier over it.

Mike, might want to check your technical sheets as I mentioned. At 1" thick, even closed cell foam won't give you much for a vapor barrier.

As a point of reference, Closed cell Icynene is 0.9 perms at 1.5" (Class II vapor retarder). 6 mil polyethylene sheeting is 0.03 perms (Class I vapor retarder).


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## mikegp (Jul 17, 2011)

Are more perms good or bad? I really want to cut down on humidity down there without running a dehumidifier. I put 6 mil poly on the floor and ran it under the sill plates running it a couple of inches up the wall with hopes to embed it within the sprayfoam for a nice seal.


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## mikegp (Jul 17, 2011)

Will it stick to poly sheeting?


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## jcrack_corn (Jun 21, 2008)

Red Squirrel said:


> Yep should be fine. I had a crawlspace professionally done, walls (cinder block) and ceiling (concrete).



yikes...

you may want to make sure this isnt an issue with your homeowners insurance.


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## Red Squirrel (Jun 29, 2009)

jcrack_corn said:


> yikes...
> 
> you may want to make sure this isnt an issue with your homeowners insurance.


Can't see why. All I know is that the energy conservation type people would love that. Will probably cut my gas bill in half this winter. When I'd stick my face in there, I could actually feel cold air rushing in and hot air rushing out, it was like a convection effect. 

The pro who did it did mention that it's flammable, but that was per code because it's an enclosed room. Even if it was to go into flames, it's an enclosed fire proof room, the fire would not go far. In fact it would probably just run out of air and stop burning.

Though I could probably build a fire resistant door in the opening. Worse case if someone did have an issue I could probably just drywall it all. Not sure how I'd do the ceiling though, just plaster? lol


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## AGWhitehouse (Jul 1, 2011)

mikegp said:


> Are more perms good or bad? I really want to cut down on humidity down there without running a dehumidifier. I put 6 mil poly on the floor and ran it under the sill plates running it a couple of inches up the wall with hopes to embed it within the sprayfoam for a nice seal.


Higher or lower perms can be either good or bad depending on the location which they are installed. The lower the perm, the less amount of moisture transmits through it in a given interval of time. The higher the perm, then greater the moisture migration.

Excessive moisture levels in a basement space should really be delt with from the outside in. Just putting measures at the interior will only delay the inevitable work that needs to be performed at the exterior. If you have excessive moisture, then drainage and exterior water proofing should be at the top of your list.


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## mikegp (Jul 17, 2011)

I don't have excessive moisture, just want to prevent any future issues. House is new and graded correctly. Tons of drainage.


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## AGWhitehouse (Jul 1, 2011)

Red Squirrel said:


> Can't see why. All I know is that the energy conservation type people would love that. Will probably cut my gas bill in half this winter. When I'd stick my face in there, I could actually feel cold air rushing in and hot air rushing out, it was like a convection effect.
> 
> The pro who did it did mention that it's flammable, but that was per code because it's an enclosed room. Even if it was to go into flames, it's an enclosed fire proof room, the fire would not go far. In fact it would probably just run out of air and stop burning.
> 
> Though I could probably build a fire resistant door in the opening. Worse case if someone did have an issue I could probably just drywall it all. Not sure how I'd do the ceiling though, just plaster? lol


In Connecticut spray foam has to be covered in concealed spaces (crawl spaces and attics. It's irrelevants the substrate it's attached to or whether there is "no air". The reason is that it is extremely flammable and when it burns it emits extremely toxic fumes. There is also the potential that it could burn hot enough that the "non-flammable" concrete could fracture and fail. Might be worth in inquiry to your insurance and local codes.


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## AGWhitehouse (Jul 1, 2011)

mikegp said:


> Will it stick to poly sheeting?


Read the technical documents for the spray foam you are interested in using. It should have the substrate requirements listed. If not, give the technical department a call, they'll tell you right away.


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## mikegp (Jul 17, 2011)

It won't stick to poly. The more I look at it the less sense it makes financially. It would cost $1800 to put 3 inches on my basement. So what should I do instead? I don't have wetness in my basement, but there's definitely some vapor. When I drywalled another section some of the dust got moldy. Is that abnormal for a basement? Does it mean I have too much moisture?


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## mikegp (Jul 17, 2011)

What about xps applied directly to the concrete wall and taped at all the seams? Using Great Stuff in and gaps. Would that be a safe way to use a vapor barrier in a basement?


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## Leah Frances (Jan 13, 2008)

mikegp said:


> What about xps applied directly to the concrete wall and taped at all the seams? Using Great Stuff in and gaps. Would that be a safe way to use a vapor barrier in a basement?


One foam or the other - you are going to have to look into the code issues about covering it.


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## gma2rjc (Nov 21, 2008)

Call the Foam-It-Green company and get their advice.


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## mikegp (Jul 17, 2011)

I mean no spray foam, just xps. Will it act as a vapor barrier?


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## AGWhitehouse (Jul 1, 2011)

mikegp said:


> I mean no spray foam, just xps. Will it act as a vapor barrier?


Rigid foam is essentially the same as spray foam once installed. Dow XPS has 1.5 perms/in so is .75 perms at 2" which is a class II vapor retarder. You can buy polyiso rigid boards which will mimic the performance characteristics of closed cell sprays.

What Leah mentioned is that rigid foam and spray foam are the same in the eyes of the code. Thermal and ignition barriers may still need to be applied to meet your local codes. In Connecticut they are required.


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## mikegp (Jul 17, 2011)

Ok, what about rigid foam with 6 mil poly over it? Is that a bad idea?


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## AGWhitehouse (Jul 1, 2011)

I personally don't like vapor barriers in basements...but there are plenty that will argue otherwise...

Problem for me is that if moisture is there then it is coming from outside the concrete, be it under slab or the other side of your wall. If the source is dealt with then there is will be no need for a vapor barrier and the system can breath to dry out what little moisture there may be residual. Putting a vapor barrier on the interior only masks the source and traps the moisture, and i feel it will eventually find it's way through....


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## Leah Frances (Jan 13, 2008)

AGWhitehouse said:


> I personally don't like vapor barriers in basements...but there are plenty that will argue otherwise...
> 
> Problem for me is that if moisture is there then it is coming from outside the concrete, be it under slab or the other side of your wall. If the source is dealt with then there is will be no need for a vapor barrier and the system can breath to dry out what little moisture there may be residual. Putting a vapor barrier on the interior only masks the source and traps the moisture, and i feel it will eventually find it's way through....


I'm also on the side of dealing with surface water (or other moisture) problems before the water gets into the basement. But I also think houses are too 'sealed-up'. 

Mike, unless you are trying to make the basement living space, why not just invest in some surface water management and a dehumidifier?


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## mikegp (Jul 17, 2011)

The basement will be half gym and half living room/tv room. I just want a nice hangout spot. It gets a little humid in the summer, isn't that normal? Concrete is like a sponge so isn't it expected to be a little humid? I was just hoping to seal it off so I wouldn't need to bother with a dehumidifier. I used radon seal a couple of weeks ago. No clue if it actually does anything, but we'll see. So far I'm pretty sold on the rigid foam against the concrete. Should I bother with insulation? If so, whats my best bet to avoid it molding. Something reasonably priced. Thanks for all of the help!


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## Leah Frances (Jan 13, 2008)

mikegp said:


> The basement will be half gym and half living room/tv room. I just want a nice hangout spot. It gets a little humid in the summer, isn't that normal? Concrete is like a sponge so isn't it expected to be a little humid? I was just hoping to seal it off so I wouldn't need to bother with a dehumidifier. I used radon seal a couple of weeks ago. No clue if it actually does anything, but we'll see. So far I'm pretty sold on the rigid foam against the concrete. Should I bother with insulation? If so, whats my best bet to avoid it molding. Something reasonably priced. Thanks for all of the help!


First, what condition are your gutters in? Is the ground around your home sloped away from the house? It's just good homeownership to make sure that rainwater is contributing to your problem. 'Sealing' up a basement wall isn't going to necessarily remediate the humidity - it depends on where they humidity is coming from. 

How humid, is humid? Get a cheap hydrometer and find out how humid it is. wallmart/hardware store will have cheapo analog ones that will give you an idea. 

IMO, if your humidity problem is not from water _intrusion_ then it would be a lot easier/cheaper/less risky to install and run a couple of good dehumidifiers than to try to seal up the basement. 

How 'bout some pics of what you've got currently. And fill us in on the plan. Are you planning on finishing the area as 'living space' (drywall, flooring etc)?You should start reading up on local codes and requirements, they may dictate how you handle the insulation issue. 

And lastly, if you get this home improvement properly permitted and inspected than you will not put your HOer insurance at risk, you will add to the value of your home, and you will legally be able to sell the home with the increase in improved square-footage. Win-win.


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## mikegp (Jul 17, 2011)

Don't have pics at the moment, but it's nothing special. Just a plain rectangular room about 16.5x30 with 9 foot ceilings. Poured concrete on 3 sides and floor. 

Gutters are clean and grading is good. I'm friends with all of the inspectors so they took special care of us when the house was being built. Probably annoyed the builders, but oh well.

It will be a gym and living room. Drywall and engineered wood floors. Nothing crazy.


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## jcrack_corn (Jun 21, 2008)

Red Squirrel said:


> *Can't see why. All I know is that the energy conservation type people would love that.* Will probably cut my gas bill in half this winter. When I'd stick my face in there, I could actually feel cold air rushing in and hot air rushing out, it was like a convection effect.
> 
> The pro who did it did mention that it's flammable, but that was per code because it's an enclosed room. Even if it was to go into flames, it's an enclosed fire proof room, the fire would not go far. In fact it would probably just run out of air and stop burning.
> 
> Though I could probably build a fire resistant door in the opening. Worse case if someone did have an issue I could probably just drywall it all. Not sure how I'd do the ceiling though, just plaster? lol


because the fire inspector people dont love it in some places, and it is specifically forbidden. And if god forbid a neighboor lands a firecracker on your roof and your insurance denies the claim b/c their policy states "no uncovered foam"

btw, it is not a sealed room from the looks of the giant hole in the wall you took pictures through, lol....the toxic fumes are an issue too.


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## BigDogNOLA (Feb 8, 2015)

Looking at your post on DIY Chatroom. I have a similar situation. I have a slab home that has been elevated 3ft off the ground. I now have an uninsulated crawl space resulting in extremely cold floors above it. Just wanted to get some info from you about the type of foam used and the prep work to ensure that it would adhere to the concrete.


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## nap (Dec 4, 2007)

Just tossing this out there;

About spraying directly to concrete; the hospital I am currently working on there is foam sprayed directly to the inside of the new concrete walls. It sticks extremely well. 

It is rated for fire for anybody concerned with that so, the bottom line is; if using the proper foam it is a proper installation.


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## mikegp (Jul 17, 2011)

I posted this back in 2011. I've probably seen it done 100 times on tv so I don't think it's an issue unless there's a temp issue or a foam issue. I just asked because someone posted on here saying it was a horrible idea.


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