Air sealing: Sheathing approach vs. Airtight Drywall Approach
To achieve airtightness in my home I’m planning to use the air tight sheathing approach as my air barrier. We are using OSB for our sheathing and plan to tape all the seams. I’ll caulk the bottom of the sheathing to the sill plate and the top will be sealed to the roofing sheathing with closed cell spray foam. We’re doing an unvented room with the rafter cavities filled with 5.5″ of closed cell spray foam.
That’s my primary air barrier. Which seems much easier than doing the air tight drywall approach or am I missing something?
With the airtight drywall approach you have to seal each top plate and bottom plate and all intersecting walls. Plus you have to seal each piece of drywall to the top and bottom plates and all the electrical boxes, direct vent fireplaces, switches and light and ceiling fan penetrations. See:
It seems it is much harder to get good sealing at the drywall. I was half thinking of doing a belt and suspenders approach to air sealing and having my primary air barrier being the sheathing and the secondary air barrier being the drywall. However looking at how hard it is to get air tight drywall I might just make sure my primary air barrier is well done.
Why do people choose the airtight drywall approach over the airtight sheathing approach when there is such a difference in complexity?