I'm looking to air seal stud bays prior to insulating with mineral wool batts. I used PL Premium polyurethane construction adhesive to seal between bottom plates and concrete as well as between double bottom plates and double top plates.

Should I use the same stuff to perimeter seal the inside of the stud bay? Or can I use Great Stuff spray foam? I ask because using Great Stuff with a spray foam gun is much quicker than running a bead of caulk out of a caulk gun.

If Great Stuff is fine for this application, which is the right GS product? Gaps and Cracks, or Windows and Doors? I know Windows and Doors will remain flexible and thus move the expansion/contraction of the lumber framing. Not sure if Gaps and Cracks will behave the same way, or if it will get too rigid and leave openings as the wood expands/contracts.

High expansion can foam such as Great Stuff is a lousy solution for sealing framing to the sheathing- even the windows & doors stuff is too expansive, and will bulge out enough to create voids & gaps with batt insulation. Those products also need moisture to cure & bond correctly, with high rates of bond failure over time if applied in sub-optimal conditions.

There are purpose made very low-expansion foam sealants such as ProPink Comfort Seal or Knauf EcoSeal, but any decent polyurethane caulk applied with a powered caulking gun works just as well and just as quickly. Polyurethane caulks bond well to wood, and remain flexible enough for life.

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Unless you're going with a dedicated sprayfoam solution (and "grab a bunch of cans of Great Stuff" isn't a solution), you're just burning money. Your coverage is going to suck, you're going to waste a bunch, and it's not going to seal well.

At that point, you're better off using a decent (and appropriate) grade of caulk.

Agreed. You guys have talked me out of that. I'll use the Loctite PL Premium poly construction adhesive I've been using for the top and bottom plates, to seal the perimeter of the stud bays.

Don't be talked out it. It's a lot more cost effective and better results using gun foam and not the Great Stuff in a 12 oz can. I use Tytan 24oz gun foam from JR Products Inc.. Cost about $8.50 per can and the coverage is a lot better that with caulk. With the gun you can control the bead and cover a lot more territory than with caulk. Buy the cheapest gun and a couple for cans of cleaner also. They have low temp and low moisture product.. It's crazy to do it with caulk. I use this product all the time.

Posted By smartwall on 25 Oct 2019 01:35 PM
Don't be talked out it. It's a lot more cost effective and better results using gun foam and not the Great Stuff in a 12 oz can. I use Tytan 24oz gun foam from JR Products Inc.. Cost about $8.50 per can and the coverage is a lot better that with caulk. With the gun you can control the bead and cover a lot more territory than with caulk. Buy the cheapest gun and a couple for cans of cleaner also. They have low temp and low moisture product.. It's crazy to do it with caulk. I use this product all the time.

I toally agree that the purpose-made super-lo-rise foam sealants are better and well worth chasing down if doing a whole house, but in his case this is just one room, possibly just one wall of one room. His other thread indicated a total wall area of 180 square feet.

His other thread also indicated gypsum sheathing, and the picture looks like asphalted fiberglass or asphalted paper facers:

https://i.imgur.com/ssCiHZy.jpg

I'm not sure what the best sealants would be most appropriate for that. He has some gap-filling to do too, and it's not clear if the brick veneer cladding is adequately vented. Any insights on the best approach to take there, without blocking off the vent space? (pending some answers to questions I posed on the other thread I might go a number of different directions.)