My house was built in 1967. I'm renovating a bathroom that is on an exterior wall. All the drywall on this wall be removed. The studs are 2x4's and I expect I'll find batt insulation. My question is how can I improve the insulation in this wall? installing rigid foam insulation and a batt or just a thicker batt?
Answer:
Neither. Rigid foam has to be cut too precisely to fit or the vapour barrier is not continuous and bats, once squeazed, start to lose their R value. Your best bet is to remove what's there and install new bats complete with 6mm poly for VB and then drywall over it. You might also pack bats around the bathtub cavity so when you soak in the bath, the water stays warmer longer. This really works.
