Stopping air leaks is the single most important part of making a house more energy efficient. You can stop air on the outside with plywood, house-wrap, and tape, but the best air barrier is more of a system that incorporates all the components of a wall or roof assembly.
We decided to drywall the garage shop in Fine Homebuilding’s project house using the airtight drywall approach. Partly to show our readers how to do it and partly so that we could make Myron Ferguson do our dirty work for us.
The outside of the house will eventually be covered with house wrap and foam sheathing, so the drywall is not the primary air barrier; it is part of a larger system.
The other main materials Myron uses in this project are pretty common on most job sites – construction adhesive, latex caulk, and canned foam. Some other materials are a little less common on jobsites, mainly foam boxes for sealing electrical outlets.
This garage has a 2x6 bottom plate, but 2x4 studs. Before Myron came out, we placed blocks in each stud cavity because without blocks to glue the bottom of the drywall sheets to, a considerable amount of air could flow through the wall assembly.
If not already done at the pre-construction walk-through, seal all of the gaps between framing members.
Around windows, around doors, at the gaps between king stud and trimmer, between header and top plate, and between the double – or triple, in the case of this shop, triple top plates.