The average homeowner probably spends as much time thinking about their home’s crawl space as they do about flossing.
For those of us who aren’t doing that twice a day, every day, it may be time to give the crawl space some added attention.
Homes in the Northwest often have a crawl space because they’re cheaper to build than homes with basements or homes built on a large concrete slab. They make it easier to install and maintain plumbing and heating infrastructure below the floor. Additionally, the vents in the foundation allow fresh air to circulate throughout the crawl space.
For years, crawl spaces were given little or no insulation. Homeowners kept the cold out by blocking the vents in their foundations. For a short but recent period of time, the trend went in the opposite direction; at great expense to the homeowner, builders and remodelers encapsulated crawl spaces. They lined them with thick plastic, insulated the ground, and installed mechanical systems to heat and ventilate the unoccupied space.
Neither approach is a good one. But those methods are just two of the many popular but improper ways to reduce energy costs associated with the crawl space.
“Everyone wants lower energy bills and a more efficient home, but, whether it is coming from your favorite uncle or from a convincing article on the internet, there’s a lot of misguided information out there,” said Clark Public Utilities Energy Services Supervisor DuWayne Dunham.
Blocking the vents in your foundation may keep heat inside during the winter, but it’s never a good idea. It traps moisture and carcinogenic radon gas under your home, which can lead to a host of structural and home health problems down the road. Some folks justify the practice by saying it prevents pipes from freezing in cold weather, but that problem can be avoided by wrapping pipes in insulation.
The internet is filled with articles that claim encapsulating the crawl space will make a home’s air healthier, dryer and warmer — but most of them are written by companies that do encapsulation and are not based on facts about the Pacific Northwest.
“Encapsulating the crawl space may work in some parts of the country, but it just isn’t a good idea locally,” Dunham said. “In fact, as a test, one local homebuilder built an encapsulated home alongside a traditional home and monitored their performances. The encapsulated home was a disappointment.”
Insulation is key
Typically, only older homes will have little or no floor insulation. New or recently constructed houses should always have it. Still, it’s a good idea to grab a flashlight and look at your home.
“In actuality, the solution to a better crawl space and a more comfortable, more affordable home, is far simpler than people may think,” he added.
Adding insulation to the underside of your floor via the crawl space will substantially improve your home’s indoor climate all year long. It should have at least R-19 insulation, but the thicker the better.
“In fact, if your crawl space needs extra insulation, Clark Public Utilities offers incentives to help make it more affordable,” Dunham said.
The ground within your crawl space should be entirely covered in a vapor barrier. Ideally it partially covers the foundation walls and the posts supporting your floor. The barrier should be at least 6 mils thick. This not only keeps moisture away from the structure of your home, but it also helps keep carcinogenic radon gas out as well. Radon is common in many parts of the county and when present, the home should have a system in place to vent it outside.
Clark Public Utilities energy counselors are available during business hours at 360-992-3355 to answer questions about crawl spaces and how to prioritize energy-saving updates to your home.
Energy Adviser is written by Clark Public Utilities. Send questions to firstname.lastname@example.org or to Energy Adviser, c/o Clark Public Utilities, P.O. Box 8900, Vancouver, WA 98668.