Plumbing Penetrations

You can follow air leakage pathways in many homes by following plumbing. The bathroom, in particular, can create air leakage and attendant moisture problems. Problems include tubs sitting against unsheathed wall studs, gaping holes in the floor underneath bathtubs and plumbing walls with large holes in their top and bottom plates.

The main vertical drain pipe (the soil or "stink" stack) is often enclosed in a wall or in its own framed enclosure, which transports air between the basement and attic through leaks at penetrations in the floor and ceiling. We referenced this in a prior writing under Air Sealing - attic.

Again, you can following plumbing out the band joist as well - typically not air sealed or hidden.

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