Reading Joe Lstiburek is always a treat. This one, a recent article that went out this week in his always entertaining newsletter, is no exception. Where else are you going to get memorable building knowledge one-liners, like:
- If radon were valuable, we would mine it this way, or
- Where there is an attached garage, we call it the Kevorkian option.
But these, quotable zingers that they are, are off-topic. This week, the real point is a not-so-obvious, obvious building error: Locating leaky ductwork in the attic. For house on slabs, this is common, and the obvious answers that often prove not-so-easy to actually do, are to bring the ductwork into the conditioned space of the house or make the ductwork not so leaky.*
Joe explores in depth the not-so-obvious option of bringing the attic into the house (a version of bringing ductwork into the conditioned space) by building a sealed attic. It works, but it has complications as Joe so adroitly covers:
The name “ridge rot” itself led to what was at the time a crazy way to fix the problem. If we can’t prevent the moisture from getting in, but we know where it all ends up, why not get rid of it when it gets there? Obvious but radical. ... How about a vapor diffusion vent? Not a vent for airflow. No airflow. Just vapor flow in the form of vapor diffusion. Guess what? It worked.
*Note to Joe: Talk to Mike MacFarland and members of the Ring 4 and Ring 5 Clubs. True, "mastic up the ying yang" is one answer, but as Mike explains (see "Making the Case for Zero-Leak Ducts") it's more about a methodical approach to duct sealing jobs using the appropriate materials. Of course, that does include mastic.