Hometap Tip: Check Your Foundation Vents and Crawl Spaces

In summer months, you may be asking yourself which vents to close, and when to open foundation vents to enable outside air to circulate under floors, preventing mildew and rot, which can cost up to $6,000 to clean up. Check and update your vents to ensure your foundation has proper air flow (while also preserving your cash flow).

What to Do

Check the vents on your home’s foundation.

What You’ll Need

The Basics

• Work gloves
• Dust mask
• Tape measure
• Screwdriver and screws
• Screens or vent covers

The Works

• Automatic vents
• Power grinder
• Masonry hammer
• Barb spring
• Caulk
• Screwdriver
• Screws (Screw anchors with retaining clips Optional)
• 6 mm plastic sheeting

How to Do It

If your home has vents in the foundation, they’ll most likely be accessible through crawl spaces (e.g., under porches or via basement access) or are visible from the home’s exterior. Count how many foundation vents you have across your entire home, measure their sizes, then decide if you want screens or automatic vents as replacements. Screen vents will need to be removed and closed for cold-weather months, while automatic vents use temperature sensors to open and close when needed.

Purchase your new screens ($3—$50 each) or automatic vents ($10—$200 each) for each vent space. To install new foundation vents, first remove any existing closures (e.g., foam blocks or grates), then make any adjustments to the vent frame size to ensure a snug fit for your replacement.

Your new vents should fit snugly to allow air flow—while also keeping out pests and vermin. If your vents are in a crawl space that has a dirt floor, you can also put down plastic sheeting ($25—$60) to block extra moisture.