Every year I’m asked the same question by homeowners that have crawlspaces: Should I close off the crawlspace vents during the winter to protect my home from the cold?
First of all it’s important to understand the purpose of these vents. A crawlspace is an ideal spot for moisture to build up which, in turn, will cause issues with mold and mildew. Crawlspace vents provide a moisture release, so I always recommend leaving those vents open all year round.
Now, there are other things you can do to help protect your home from those cold winter floors, like adding insulation between the floor joists and putting a moisture barrier on the ground using a thick plastic sheeting.
Also, be sure no plants are blocking the vents to allow good air circulation.