Podcast Episode 751: Disaster Mansion, Drippy Ceilings, and Insulating Existing Walls

This week's Fine Homebuilding Podcast takes listener questions on two problems that show up in older homes. One listener, John, wrote in about his half bath, where condensation has started forming on the ceiling and crown molding and dripping onto the floor in the peak of summer. The room sits on an exterior wall and was added without a duct connecting it to the home's central heating and cooling. He had already cleaned and repainted the surfaces, thinking old stains might be to blame, but the wet ceiling came back worse this year. The hosts work through why a small, unconditioned bathroom on an outside wall might be prone to this kind of moisture buildup in hot weather, and what that means for the room's air flow and temperature.

The second question comes from a homeowner in Michigan planning to gut the interior of a few 100-year-old houses down to the studs. He wants to boost wall insulation and seal air leaks without losing much interior space or spending too much, and describes a plan using furring strips made from rigid foam sheathing, spray foam in the stud cavities, and mineral wool batts to reach an R-value of 28 while cutting down on heat loss through the studs themselves (called thermal bridging). The hosts discuss whether that approach makes sense compared to simpler options.

The episode also includes listener stories: one about a couple restoring a Civil War–era house they bought at auction, and another about a homeowner who kept an old plaque documenting the insulation used during a renovation. If you're dealing with a musty bathroom or planning a gut renovation on an older house, these listener questions and the hosts' back-and-forth may be worth a listen.