Caulking and Spray Foam Insulation
They say it’s the little things that count. Don’t underestimate the value of properly sealing openings, even the smallest of ones. Air migrates through the smallest of cracks, so it’s really important to pay attention to this detail.
When I was in the attic and basement inspecting my insulation, I noticed light coming from the living space in many locations. Armed with a caulk gun in my holster and a can of spray foam at my side, I systematically attacked all these openings. I was amazed that when I pulled back the insulation around light fixtures and at the ceiling and floor diffusers I could actually see into the house! Clearly if I could see in, conditioned air could escape and unconditioned air can enter where I don’t want it. I mostly used the spray foam, going through many cans, to seal around all these openings. Just like the mastic, it doesn’t have to be pretty, it just needs to cover all the gaps. Of course, if you want to make it pretty, feel free, but I know for myself anyway that I have other things that need that level of attention…
I also spent the time to seal all the holes where electrical wires and plumbing pipes were run. You may think that was a waste of time, but hear me out. A hole that’s not sealed from the attic or crawlspace allows unconditioned air to penetrate the cavity of the wall, even on an interior wall. This air can then enter the house (or conditioned air to leave the house) though electrical outlets or switches, or where plumbing lines enter the house like in a sink cabinet. This air is also unhealthy, coming from your attic or crawlspace.