Opinions on Spray Foam?

[em12]

Hey guys, I built a 24 x 24 shop with 9 ft wall height and 12 in the center.... I put an 18,500 btu wall unit ac out there. The quotes for foam I am getting are for 1 inch of closed cell. How effective will 1 inch be for me in that space? Thank you.

[mmoses]

very effective. That is only a R6 rating but its airtight, It will help a bunch.

[sec]

I had 1 inch sprayed in a 24 x 30 and it stayed about 10-13 degrees cooler in the summer than outside temp with no AC and stays warmer in the winter by about the same

[Mike D]

Worth every penny.


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[em12]

Real question I guess is do I really need to spend more money and go thicker....? For another 900 bucks I could get another inch.... but I am happy enough with the 1 inch price whereas the 2 inch puts me at more than I really wanted to spend....

[Dale Moser]

1 Inch will be awesome! If you're close on budget, I wouldn't worry about doing more, use it somewhere else.

[em12]

1 Inch will be awesome! If you're close on budget, I wouldn't worry about doing more, use it somewhere else.

Perfect- thank you gentleman. That makes me feel good about it. I appreciate the information.

[Roscoe]

Real question I guess is do I really need to spend more money and go thicker....? For another 900 bucks I could get another inch.... but I am happy enough with the 1 inch price whereas the 2 inch puts me at more than I really wanted to spend....

We’ve got 1” closed cell in the 24x30 shop we had built last year. I really don’t think going thicker would be of much benefit. In August last year when the sun would be beating down on the back wall of the Bldg every afternoon, it was a little warm to the touch at worst.


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[Banded Drake Calls]

For what it's worth, just know that at 1 inch, closed cell foam is not going to provide your metal with any moisture barrier. You could develop issues of moisture settling in between the foam and metal causing significant rust issues, I've seen it first hand with metal sprayed with open cell which also has no moisture barrier capabilities. You need at least 1.5" of closed cell foam to achieve that. If you could swing it in your budget I would push it to at the minimum of 1.5", otherwise you may as well just have them spray 3" of open cell to give you more R value and take the hit with moisture issues that you'll develop with 1 inch of closed cell

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[RascalArms]

Hey guys, I built a 24 x 24 shop with 9 ft wall height and 12 in the center.... I put an 18,500 btu wall unit ac out there. The quotes for foam I am getting are for 1 inch of closed cell. How effective will 1 inch be for me in that space? Thank you.

From an R value and temperature standpoint 1” of closed cell will be very effective in that small amount of space but if it were me, I would go with 2” in the roof line for moisture barrier purposes.

For what it's worth, just know that at 1” closed cell foam in not going to provide your metal with any moisture barrier. You could develop issues of moisture settling in between the foam and metal causing significant rust issues, I've seen it first hand with metal sprayed with open cell which also has no moisture barrier capabilities. You need at least 1.5" of closed cell foam to achieve that. If you could swing it in your budget I would push it to at the minimum of 1.5", otherwise you may as well just have them spray 3" of open cell to give you more R value and take the hit with moisture issues that you'll develop with 1 inch of closed cell

EDIT: This is my understanding and what my builder said as well. Supposedly it takes at least 1.5” closed cell to act as a true moisture barrier. We recently built a 30x50 shop with a 4:12 pitch roof line and 12’ side walls with a center height of 16’. We went with 2” closed cell foam in the roof and 1” in the walls.

Closed cell spray foam is darn good stuff....not cheap but worth every penny IMO. Buy once Cry once IMO.

[Big pig]

From an R value and temperature standpoint 1” of closed cell will be very effective in that small amount of space but if it were me, I would go with 2” in the roof line for moisture barrier purposes.


EDIT: This is my understanding and what my builder said as well. Supposedly it takes at least 1.5” closed cell to act as a true moisture barrier. We recently built a 30x50 shop with a 4:12 pitch roof line and 12’ side walls with a center height of 16’. We went with 2” closed cell foam in the roof and 1” in the walls.

Closed cell spray foam is darn good stuff....not cheap but worth every penny IMO. Buy once Cry once IMO.

How much did you have to pay (cry) For that 1,500 sized shop for the 1”/2” combination? I’m building now and over budget already.
Thanks !

Big pig

[sasqy]

Only way to go !

[Roscoe]

For what it's worth, just know that at 1 inch, closed cell foam is not going to provide your metal with any moisture barrier. You could develop issues of moisture settling in between the foam and metal causing significant rust issues, I've seen it first hand with metal sprayed with open cell which also has no moisture barrier capabilities. You need at least 1.5" of closed cell foam to achieve that. If you could swing it in your budget I would push it to at the minimum of 1.5", otherwise you may as well just have them spray 3" of open cell to give you more R value and take the hit with moisture issues that you'll develop with 1 inch of closed cell

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Does painting the closed cell afterwards offer any help in regards to the moisture aspect?


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[Banded Drake Calls]

Does painting the closed cell afterwards offer any help in regards to the moisture aspect?


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Only if you paint with something that is rated as a vapor barrier. Not all paints offer that as a protection. Most vapor barrier paints will have a mil thickness they have to be applied at to work, same as closed cell foam. Also remember that foam, even closed cell, is porous and will soak up some of the paint before you can get your mil thickness. Cost wise it may be more cost effective to add the 1/2 inch to the foam then you can paint with whatever you would like in any color you would like. In general, closed cell foam costs about .50 to .53 per board ft in material, so for 1 inch of foam that would be the sq ft cost. Adding half an inch would only be about another .25 per square ft. They're already there spraying, adding a half inch doesnt take much more time to get for the man operating the gun. An honest spray foam company would reflect that in their cost

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[Craw3773]

For what it's worth, just know that at 1 inch, closed cell foam is not going to provide your metal with any moisture barrier. You could develop issues of moisture settling in between the foam and metal causing significant rust issues, I've seen it first hand with metal sprayed with open cell which also has no moisture barrier capabilities. You need at least 1.5" of closed cell foam to achieve that. If you could swing it in your budget I would push it to at the minimum of 1.5", otherwise you may as well just have them spray 3" of open cell to give you more R value and take the hit with moisture issues that you'll develop with 1 inch of closed cell

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I dont understand how thicker would protect your metal better. Yes, you need 1.5" to create a moisture barrier, but that will prevent moisture from getting to the interior of the wall assembly. if moisture is going to enter a penetration in the metal, and cause condensation between the foam and metal, that's going to happen in any case.

Putting less foam, may allow that moisture to move through the wall assembly. while that would not be a good situation for a home, it may be just fine for a barn, and actually preserve your metal better.