However, crawl spaces are often neglected during these efforts. Crawl spaces are more exposed to outside winds due to their vents. Thus, a little brush with cold winds is enough to freeze crawl space pipes.
The freezing temperature of water is 32°F (0°C or 273.15 K), and when it freezes water can expand by up to 10%. The outside temperature generally needs to be lower than this to freeze a pipe, depending on the measures in place within your home.
With a vented crawlspace, there is a chance that the crawlspace air could get very cold. But the risk of the ground freezing in the center of the crawlspace is still minimal.
Block Off Vents: In cold climates, consider blocking off crawl space vents during winter to retain heat, but ensure there's still some ventilation to prevent moisture problems. Install Grilles: For better airflow, install grilles or louvered doors to allow air circulation while maintaining some warmth.
Winter temperatures in crawl spaces are generally warmer than the outside air due to ground insulation. However, they can still range from just above freezing to around 50°F, depending on insulation and conditioning.
The cause of cold floors above the crawl space is air flow. Crawl spaces are not sealed off from the outside, and they are frequently under-insulated. In the winter time, cold air from the outside enters the crawl space through vents and gaps in the structure.
In winter, particularly in cold climates, closing crawl-space vents can help prevent cold air from entering the space and potentially freezing pipes. The simplest way to close foundation vents for the winter is to plug them from the outside with foam blocks made specifically for this purpose.
Most building codes require insulation in areas like crawl spaces. It is usually placed between floor joists or on walls. This material is essential for temperature regulation and energy efficiency in your crawl space and throughout your home, but it's not without its problems.
Encapsulation reduces the chances of pipes freezing by preventing cold air from entering the crawl space, as it keeps the temperature within the space more consistent and above freezing even during cold spells.
When ground temperatures drop to 0°C (32°F), the water trapped in sediment, soil, and pores of rocks turns to ice. Once frozen, it is considered frozen ground. When ground remains frozen for at least two consecutive years, it is known as permafrost.
Why Install a Crawl Space Barrier? Crawl spaces are prone to dampness and can become breeding grounds for mold and mildew. To prevent this, a vapor barrier shields against moisture from the earth entering the crawlspace.
Your pipes are at risk of freezing any time temperatures drop below 32°F. However, it's much more common for pipes to freeze when temperatures dip below 20°F. The longer the weather remains below freezing, the more likely it is your pipes can freeze if not properly protected and winterized.
Insulation Falling in Crawl Space Ceiling
Over time gravity can lead to fiberglass insulation under the house falling down from the ceiling of the crawl space open to cold air and making your floors colder. Essentially when this happens you're left with no working insulation under the house.
Closing crawl space vents in the winter is a good idea, especially if you have plumbing or air ducts in the crawl space. Unfortunately, just closing or covering crawl space vents for the winter isn't the cure-all for cold floors, frozen pipes, and pests.
Insulation – To insulate the foundation walls of the crawlspace, the most effective insulation system is to use two-part spray foam. Either open cell or closed cell will both work just fine.
Closing your vents prevents airflow, which can retain heat. Open vents move air but lack security from outside effects. Secure your vents with vent covers to prevent pests. Fully encapsulating your crawl space is the most expensive but best option.
Cost by Size
Your crawl space's size has one of the biggest impacts on price since larger areas require more materials and labor to encapsulate. A basic encapsulation project costs between $3 and $7 per square foot, but the cost can go up to $10 per square foot for crawl spaces with an extensive moisture problem.
Apply heat to the section of pipe using an electric heating pad wrapped around the pipe, an electric hair dryer, a portable space heater (kept away from flammable materials), or by wrapping pipes with towels soaked in hot water.
Best Practice: Install crawl space vent covers on the outside of the vent openings of the encapsulated crawl space. Seal the rim joists with rigid foam board insulation and use foam sealant to seal the opening between the top of the crawl space wall and the sill.
Having cold floors in the winter is likely caused by poor insulation in your home's rim joist or crawl space - areas connected to the foundation.
According to the IRC, a crawl space should have one square foot of screened vent for every 150 square feet of space. To further reduce moisture, homeowners can cover bare ground with an approved vapor-barrier material. So yes you need ventilation.