Hey everyone! I recently moved into an old single-story home from the late 70s, and this is my first winter here in southern Illinois. The cold weather has really jacked up our power bill, even more than my parents' bigger house! I took a peek under the house and found no insulation in the floor joists, which of course is something I plan to tackle. The crawl space has a plastic liner on the ground and walls, and I'm thinking of putting foam board insulation in the rim joists to properly seal things up. My question is about the crawl space vents. I've seen conflicting advice online about whether to keep the vents open all year, close them, or switch them based on the season. Considering the vapor barrier I have and the insulation I plan to install, won't my moisture levels be low? It seems strange to insulate and still let cold air in during the winter and hot air in during the summer. Any ideas?
2 Answers
I’ve been working on encapsulating my crawl space and I've found sealing the vents year-round has made a huge difference. The key is to consider the outside conditions; if it’s hot, the crawl space will be hot if the vents are open. Keeping them sealed helps with energy efficiency and humidity control, especially in humid areas, so I say keep them shut!
Definitely seal those vents up for the winter, especially in Illinois! Your home is just losing heat like crazy with those open. Covering them will help keep your house warm and save on those bills.
I noticed the vents look like they have some old vapor liner blocking them. I’ll definitely seal them with foam board first thing tomorrow. Do you think it’s okay to keep them covered in the summer too?
That sounds like what I was leaning towards. Is your crawl space floor encapsulated? Have you faced any humidity or mold issues?