I've been dealing with some high humidity levels in my crawlspace, especially with all the rain and heat we've been having in north central Indiana. Right now, the temperature sits at about 65°F, but humidity is around 80%, which feels too high, especially since the outdoor humidity is usually lower.
Here's a quick overview of my setup: I've got a geothermal heat/cool system down there, and the walls are insulated with spray foam. There's also plastic sheeting that looks like a vapor barrier, but it's not completely covering the dirt in some spots. No sump pump is installed, but I haven't noticed too much standing water, aside from a bit around a replaced condensate pump.
I had some manual foundation vents that were in bad shape, so I've swapped them for automatic vents that open and close at certain temperatures. My plan is to clean up and tape the vapor barrier properly and possibly replace the automatic vents with permanently closed ones.
Does anyone have additional suggestions for reducing that humidity?
3 Answers
Honestly, I wouldn't stress too much about it now. Just keep an eye on the weather trends for next year. You might want to inspect your geothermal system just to rule out any leaks, but it could just be normal condensation behavior too.
I think it’s a good call to seal the vents and keep the crawlspace insulated. Just make sure you have a solid vapor barrier on the ceiling too, as that can contribute to humidity issues. Definitely worth checking out!
It might actually be better to seal off your crawlspace completely! When outside hot air enters, it increases the relative humidity inside since that cooler air can't hold as much moisture. So, I'd advise getting that vapor barrier sorted and keeping it air-conditioned or dehumidified. If you've got flooding issues, a sump pump is a good idea, but it doesn't sound urgent right now. Also, check out Dr. Allison Bailes III's book; it breaks down home ventilation in a really easy-to-understand way!
You're spot on! No need for vents if your crawlspace is already insulated and has a good vapor barrier.
Totally agree on sealing it up. I had my vents closed and a dehumidifier installed when we moved into our home, and it made a huge difference!