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spray foam/ open cell vs. closed cell
- Thread starter dshop
- Start date
cajunfirehawk
Well-known member
73RR
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^^^^excellent read!
For the average guy-on-the-street, the only real difference is cost per inch of R. I have used both, in many different buildings, and had excellent results with each, for its intended purpose.
The advantage of using foam is that it absolutely seals the wall cavity. The is no air movement.
Are you using foam in the just the walls or also spraying the roof? It is possible to spray the entire roof structure and turn the shop into a giant picnic cooler but you will need to consider fresh air if the doors stay closed for long periods.
For the average guy-on-the-street, the only real difference is cost per inch of R. I have used both, in many different buildings, and had excellent results with each, for its intended purpose.
The advantage of using foam is that it absolutely seals the wall cavity. The is no air movement.
Are you using foam in the just the walls or also spraying the roof? It is possible to spray the entire roof structure and turn the shop into a giant picnic cooler but you will need to consider fresh air if the doors stay closed for long periods.
Last edited:
theoldwizard1
Well-known member
A sponge is an example of open cell foam. It ABSORBS AND HOLD WATER !!
A sponge is an example of open cell foam. It ABSORBS AND HOLD WATER !!
I don't use the sponge that is in my kitchen very often, because I have a dishwasher and use paper towels. With a relative humidity of 60% it is dry as a bone. A quote from the reference quoted in post #2:
"On the other hand, the structure of open cell foam is not nearly as strong and it will take on water if a leak is bad enough. In the case of a roof leak or wind driven rain, open cell will simply dry out and return to normal once the leak is stopped."
73RR
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With spray foaming an entire shop, is it beneficial to use house wrap, or just skip that material?
House wrap is expensive and does nothing for a foamed wall except to act as a slip-sheet under the siding. 15lb felt will do the same job for less money.
You will never have any issues with a good closed cell foam job -- I would do a flash and batt w/closed over open. I did one about 10 years ago.
Having a rain shedding underlayment under the siding is still a good idea for some siding products. You want to make sure the sheathing will dry to the outside w/ closed .. and no vapor barrier with closed foam.
Open foam allows moisture to flow -- it needs to be very thick in some climates.
Having a rain shedding underlayment under the siding is still a good idea for some siding products. You want to make sure the sheathing will dry to the outside w/ closed .. and no vapor barrier with closed foam.
Open foam allows moisture to flow -- it needs to be very thick in some climates.
I had a 50x72 pole barn built. I spent a bunch of time obsessing over foam vs traditional, open vs closed, etc.
I went with closed cell. It is TOUGH! Like the original foam great stuff sealant stuff.
It is a vapor barrier. Hence, the wrap is a not necessary.
The closed cell "ties" the building together. Much more strength in the building. Not much of a benefit in a stick built constructions.
It WORKS AWESOME! I am so impressed with its insulation/ sealing qualities, I would do it again in a second.
I put in a tin ceiling in my "shop side". It has 4" of open cell on top of it, as the vapor barrier quality did not matter, and price was much better.
So, is it worth the cost? In NC? up to you. Does it perform as well as advertised? YUP
you can stand inside my shop when it is zero outside. Feel the foam, and the surface of the foam is regular shop temp. It is so impressive.
Wags
I went with closed cell. It is TOUGH! Like the original foam great stuff sealant stuff.
It is a vapor barrier. Hence, the wrap is a not necessary.
The closed cell "ties" the building together. Much more strength in the building. Not much of a benefit in a stick built constructions.
It WORKS AWESOME! I am so impressed with its insulation/ sealing qualities, I would do it again in a second.
I put in a tin ceiling in my "shop side". It has 4" of open cell on top of it, as the vapor barrier quality did not matter, and price was much better.
So, is it worth the cost? In NC? up to you. Does it perform as well as advertised? YUP
you can stand inside my shop when it is zero outside. Feel the foam, and the surface of the foam is regular shop temp. It is so impressive.
Wags