Double-wall framing is the same thing as single wall framing, it just takes twice as long. sort of.
One way to frame double-stud walls is to frame the regular outside walls first and then frame another set of walls inside.
Step by step:
Begin by butting some plate stock against the existing bottom plates.
- Measure the thickness of the wall that you want to end with. Measure back 3.5 inches to signify where the perpendicular wall will sit. This 3.5-inch mark will be a cut line later so that there is no framing connection between inside and out. But don’t cut it yet. It’s easier to get the layout with the ends butted tightly against the other wall.
- Scribe all of the studs, including window and door openings using a speed square or combination square.
- Speaking of window openings, when you scribe the stud placements, make the opening on the inner wall about a quarter-inch larger on each side.
- The other thing is to frame the rough openings larger than the window schedule calls for, to accommodate window bucks made from leftover subflooring. The window bucks provide a continuous solid layer to waterproof and air seal to. Cut the bucks a little narrower than the wall thickness. Because unlike animation land, actual wood is not ideally sized and shaped, so it’s good to have wiggle room. The openings can be shimmed square on the inside.
That’s pretty much most of it except for interior wall tie-ins. Frame interior walls after the double walls are complete. Full-height backing gives the insulators continuous backing to staple netting to.
If you use ladder backing, the insulation can puff out between the blocks, which makes the drywallers crabby.
Walls like this push the envelope on construction quality. And that’s nothing to be crabby about.
—This animated detail is based on jobsite footage of Ben Bogie, with Kolbert Building, while he and his crew constructed a superinsulated house near Portland, Maine. Thank you Kolbert Building for supplying the site, and Thank you, Ben, for the technical guidance.