Should You Close Your Crawl-space Vents for Winter?

If your home sits on a typical crawl-space foundation, chances are you have crawl-space vents. While many cities require these vents as part of building codes, not all homeowners understand how or when to use them. Here’s a quick explanation to help you minimize moisture in your crawl space while also protecting your water pipes from freezing in the winter.

West of the Cascades: Open in the Winter/Close in the Summer

Foundation vents were initially invented to control the damaging effects of humidity under a home. While it might seem odd, most homeowners west of the Cascades open and close these vents at the wrong time of year.

In the summer, when outdoor humidity is the highest, the foundation vents should be closed to keep the moisture out. In the winter, the idea is to open the vents to push damp air out and allow for circulation. In some parts of the valley, vents can be left all year long.

East of the Cascades: Close in the Winter/Open in the Summer


If you live anywhere east of the Cascades, or another region where winter temperatures regularly fall below freezing, it can be a good idea to close your crawl-space vents in the winter and open them in the summer. Styrofoam vent inserts can make this chore easy and effective.

Avoid Frozen Pipes

Even if you don’t live east of the Cascades, close and insulate vents under or near any sinks on outside walls just in case. If you have a crawl-space vent under a sink, close it and insulate the pipes for added insurance.

Keep Critters Out

Closing up vents can help keep critters out of your crawl space during the coldest parts of winter. Don’t live in an area that gets snow or freezing temperatures? Reinforce the screens on your crawl space to keep raccoons, rats and other uninvited guests out.

A Word on Radon Gas


Radon is a natural, dangerous gas formed from radioactive decay deep in the ground. Whether you have a crawl-space foundation, slab foundation, or basement, that gas can enter your home from the soil below it. While open foundation vents (open for several months out of the year), a soil vapor barrier, and/or room pressurization may help reduce the amount of radon gas entering a home, the Environmental Protection Agency (EPA) suggests all homeowners get their home tested for radon gas and hire a professional to control the problem.

Get Your Crawl-Space Vent Covers at Coastal

You’ll also find humidity remedies for your home, RV and more, along with pest control methods. Stop by your West Coast-owned and operated Coastal and find everything you need for your country way of life.