Builders love to talk about walls. Almost all of us are willing to argue about the best way to build a high-R wall, and we love to debate whether certain wall details are environmentally friendly enough to be considered “green.”
Although these conversations can be fun, our obsession with wall details is often misplaced. Details that inflame our passions are often irrelevant. In most cases, we should just choose a relatively airtight easy-to-build wall with good flashing details — one with an R-value in the range of R-20 to R-40 — and be done with it.
I probably shouldn’t admit this fact, but it’s true: when a GBA reader posts a question proposing a new type of wall assembly, I sometimes sigh. I wonder whether it’s time to dial back our wall discussions and to spend more time talking about air barriers or windows.
Two popular approaches
Now that I’ve gotten my rant out of the way, I’ll provide some advice on walls. For readers who don’t have time to get bogged down in details, here’s the short version of my wall advice:
Energy-conscious builders in North America have been building double-stud walls for at least forty years. (In 1978, for example, Gene Leger built an energy-efficient house with cellulose-insulated double-stud walls in East Pepperell, Massachusetts.)
For more information on double-stud walls, see the following GBA articles:
Double-stud walls have two parallel framed walls — either two 2×4 walls, or one 2×4 wall and one 2×6 wall. The total wall thickness is variable; while 12-inch-thick walls are common, it’s also possible to build a double-stud wall that is 9 inches thick or 14 inches thick.
If you plan to build a double-stud wall, you need to decide which of…