When winter comes around, a lot of homeowners start wondering if they should keep crawl space vents open or closed when the temperature starts dropping. The truth is, a lot of homeowners just don’t know what to do with those little windows around the outside of their foundation. Whether they’re used to slabs or were just never taught, this leads to a lot of expensive mistakes. Let’s talk about your vents, winter home health, and why crawl space encapsulation not only removes the confusion but could also save you money long term.
The Short Answer
If you want to skip the long, drawn-out response but have just enough information to start an argument with someone who heard it differently, the answer to whether crawl space vents should be open or closed is that they should always be closed in the winter. It’s the safer choice for any home when the temperature drops. That doesn’t stop it from becoming a hot debate on social media and even among some professionals who should know better. There are several good reasons why you need to keep them closed.
Open Vents Encourage Condensation In The Winter
In the winter, you keep your living areas heated, which creates a pocket of warm, dry air. The structure surrounding this pocket also heats up some. A wide-open crawl space brings in colder air from the outside that is filled with moisture. As this air hits the warmer surfaces in your crawlspace, the moisture is drawn out, creating droplets of condensation in your crawlspace. Since more moist, cool air is continuously coming in, this moisture becomes trapped.
Moisture Seeps In, Weakening Your Home
Moisture trapped under your home’s floorboards is not your friend. It rots wood, damages concrete and cement, and attracts pests. Bugs and rodents look for warm areas with plenty of food and water in the wintertime. Crawl space vents that are open or not closed fully help make sure they can find both under your floorboards, where they can also chew on wood, wires, insulation, or anything else they want.
Open Vents Reduce Heating Efficiency
While cool air drawn into your crawl space from outside is heated to produce condensation, it also cools the structure of your home, forcing your furnace to work harder to maintain temperature. This can cause increased utility usage, even if your floor is tightly sealed. If you have an older wooden floor that has some well-weathered gaps, this becomes an easy way to let cold air into the house from outside through open or not fully closed crawl space vents, further increasing your heating costs.
Stacking Up The Heating Costs
This cold airflow contributes to something called the “Stack Effect”. Heat in your home naturally rises before being dissipated out through attic vents, openings, or just radiating through your roof. Cold air entering underneath the home at the same time creates a system of airflow that works similar to a chimney, constantly moving cold air in, hot air out, and creating an expensive loop that sucks up your energy dollars.
Unless you have invested in crawl space encapsulation, your crawlspace gets a lot of dust, pollen, and mold spores from the air outside. When you enter the stack effect, these contaminants are pulled into the house and dispersed through the entire home, jeopardizing the health of every occupant.
Potential Pipe Damage
When temperatures dip into freezing territory, your pipes are in danger. Expanding water freezing inside a pipe can easily burst it, causing not only a large water bill and plumbing-repair costs but also added moisture that has to be manually removed from beneath your house before rot can set in. Open crawl space vents help close your pipes up with frozen water faster, increasing the likelihood of a burst pipe.
Protecting Your Crawl Space
It’s plain the question of whether your crawl space vents should be open or closed during winter is straightforward. Your vents need to be closed to prevent cool, moist air from getting under your house. The cold air isn’t the only way moisture can enter your crawlspace, however, and that could be where the confusion about closing vents comes from. That is also why crawl space encapsulation is such a good idea.
The cold temperatures don’t just cool the air, but also the ground, which sucks up moisture itself. In an unprotected crawlspace, even with vents closed, this cold, moist soil can introduce water into your crawl space, which with the vents closed, still becomes trapped. It’s easy to see how someone could think the easy answer was to either open the vents or open them “just a little”. It just doesn’t work.
Crawl Space Encapsulation
Encapsulation takes the question of whether crawl space vents should be open or closed off your plate, as they are sealed shut as part of a comprehensive moisture control plan. A ground moisture barrier is placed, vents are sealed, and appropriate insulation is installed to provide a controlled, protected environment under your floorboards.
This not only helps lower your heating costs in the winter and cooling costs in the summer but it also helps prevent damage to your foundation, joists floorboards, pipes, and insulation as well as helping prevent pest infestation by not giving them a hospitable environment to thrive in.
Schedule Your Free Inspection
If you aren’t sure how many years your crawl space vents have been open (or closed), your crawl space may need immediate attention. You can schedule a free consultation with a waterproofing professional today. This no-obligation visit will let an expert examine your crawl space, looking for existing damage and mitigation options that can protect your property and save you money. Then, they’ll provide a free estimate that gives you what you need to make an informed decision.
With decades of experience helping their neighbors preserve and protect their homes, you can be sure you’re getting help from a team that has the tools, training, and experience to get the job done. All projects come with a lifetime warranty. Once you decide on the best protection for your home, we’ll help you understand the costs, timeline, and expected schedule so there are no surprises–just results.
Take the first step toward better crawl space waterproofing. Schedule your free visit with AM Wall Anchor & Waterproofing today.