Posted By jonr on 28 Apr 2014 11:01 PM
With that on the inside and something (building wrap, taped OSB, taped foam) on the outside, you have two good air barriers and I don't see the point in using sealant in the stud cavities.

The point of sealing the stud bays is to stop air movement in the cavity. Its very hard to seal top and bottom edges of sheathing from the outside effectively. Field seams are a bit easier to seal. Building wrap does very little air sealing work as typically applied.

Posted By greentree on 29 Apr 2014 06:54 AM
The point of sealing the stud bays is to stop air movement in the cavity. Its very hard to seal top and bottom edges of sheathing from the outside effectively. Field seams are a bit easier to seal. Building wrap does very little air sealing work as typically applied.

This is coming from a guy who hangs drywall ceilings and runs a pre-insulation framing blower door test which by the way I would highly recommend. In fact do it prior to any wall sealing but after your building wrap, you will quickly get the picture.

Posted By FBBP on 29 Apr 2014 11:07 PM

Insert house wrap between the top plates. Tape it down over the wall house wrap. Seal it to the ceiling vapour barrier.

That sounds like a good simple solution, but have you verified its effectiveness? Would also cost a lot in labor and tape. Using that method I would have issues with truss hardware, general punctures of the wrap and the questionable durability of wrb tape. Oftentimes some holes are made after siding is on which would make it impossible to seal at the plane of the housewrap. How much does this method cost and what are the results?