Is It A Good Idea to Close Off Crawl Space Vents in Winter?

Crawl space vents aren't airtight, meaning they will allow air exchange and perpetuate problems like mold growth, mustiness, and rotted floor joists. You need to seal them properly.

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Winter in Washington, D.C., can be harsh with frost, ice storms, and cold temperatures assaulting your home. Your vented crawl space will likely take a beating. Because of this, you want to make sure your home is warm. 

Crawl space vents have to remain sealed during this time. While this contravenes longtime building standards, it’s a smart thing to do. Remember, you can’t control what happens in the crawl space if vents remain open. 

Sealing these fixtures will result in a dry crawl space and translate into a warm, comfortable home. No more curling toes or cringing at the thought of brushing up against cold walls. 

cover open crawl space vents

Why Seal Vents? 

Winter is a time when cold air enters the house through openings and warm indoor air escapes. The air from the outside doesn’t just affect the conditions in your home but also within the crawl space. The stack effect will keep your floors and walls perpetually cold. And there’s the risk of frozen water lines and burst pipes, the leading cause of flooding in winter. 

  • Benefits of Sealing Crawl Space Vents 

Until you seal the vents, you can’t fully appreciate what vent covers do to your crawl space. Here are some of the benefits. 

  • Curbs indoor humidity 

While the winter air is less moist than summer, the uncontrolled airflow through the vents means moisture can build up and cause problems. High indoor humidity is behind many crawl space problems as you’ll see. 

  • Crawl space condensation 

Typical of homes with crawl spaces, condensation will happen. The question isn’t if, but when. Condensation occurs when the cold air flows in and causes the indoor air to give up its moisture. Water droplets will form on your walls and insulation material. 

  • Prevents wood rot 

Outside air that flows in unabated can also instigate wood rot, weakening floor joists and girders and rendering them ineffective in supporting your home. Wood rot happens when the wood gets saturated or has 20-29% moisture content. You can stop wood deterioration by sealing the vents. 

  • Fresh indoor air 

More than half of the air that gets into your home originates from your vented crawl space. This air doesn’t just bring in moisture, but all the nasty particles, allergens, mites, and bacteria that float aimlessly in the crawl space atmosphere. When upward-moving air gets into your home, it can cause respiratory health problems. These microorganisms make the air stale, stuffy, and unbreathable. 

  • Prevents costly repairs 

When water and mold attack the crawl space, it’s going to weaken your supporting structures and damage insulation. Sealing vents will stop both from ruining your crawl space and compromising your home’s structural integrity. 

  • Energy-efficient home 

Perhaps you haven’t been paying attention to your utility costs in winter. Try monitoring them for the three months of winter, and you’ll realize they are way higher than the rest of the year. Reason? You’re heating the home, but the vented crawl space slows down the rate at which your home heats up. This is another way of saying you’ll run your heater for hours to attain the desired temperatures. 

The Smart Way to Cover Crawl Space Vents 

There are many ways of sealing crawl space vents. Some homeowners use foam blocks while others slide existing louvers into place from the outside. Still others use automatic covers that shut on their own when temperatures drop. 

You can protect your crawl space and your home by installing CrawlSeal™Crawl Space Vent Covers over your old vents. Made from fade-resistant and durable plastic, these fixtures will keep the crawl space dry and your home healthy. Installation is straightforward and fast. Once the covers are in place, you won’t need to repaint or replace them. They’ll serve you well for many years. 

But it’s not enough to simply have these covers placed over your vents and call it a day. You need to make sure your crawl space stays safe, healthy, and completely closed off from the elements. Depending on the condition of your crawl space, this can include various crawl space solutions like waterproofing with interior drainage and a sump pump, encapsulation, insulation, and dehumidification. To find out more about crawl space covers and other crawl space repair solutions, schedule a free inspection with the experts at JES Foundation Repair.

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