An insulated crawl space creates a more energy-efficient home and protects against weather extremes. Insulation is also a building code requirement, though it varies from state to state and even between counties. Three main types of insulation for crawl spaces are found in homes in the greater Charlotte, North Carolina area. Let’s look at each of them and which crawl space floor insulation is best for your home. You can watch the video or if you prefer, read the article below.
How to Insulate a Crawl Space?
In order to determine how to insulate a crawl space, we must first determine which type of insulation to use. The most common type of insulation in homes in our area by far is fiberglass batt insulation. You will normally find it throughout the home, and in basements and crawl spaces, it is usually found between the floor joists. Fiberglass batted insulation is a fluffy material, similar in appearance to cotton candy, with a paper backing. It comes in large rolls and is easy to cut, making it the preferred insulation for DIYers. Batt insulation also comes in other materials such as wool and cellulose, but fiberglass is the most commonly used.
One of the drawbacks to using batt insulation in a crawl space is that the porous material is subject to mold in a moist environment. If a crawl space is not fully encapsulated with a dehumidifier, it will have moisture in our high-humidity climate in North Carolina, which can lead to mold. Once fiberglass insulation is exposed to mold, it must be removed and replaced with new insulation materials.
Is Open/Closed Cell Spray Foam Good for Crawl Space Insulation?
Spray foam insulation is a type of polyurethane plastic that is sprayed on and expands, creating an airtight seal around cracks and gaps. Spray foam is often used on entire walls or ceilings and is excellent at reducing heat transference.
Although this type of insulation can be beneficial in interior walls or attics, we do not recommend using it in a crawl space. Once it is applied, spray foam insulation is not easily removed. If this type of insulation is used between the floor joists, it will essentially cover up any evidence of moisture, insect activity, or plumbing leaks from above the floor system. By the time these issues are noticed, the damage is already done and the cost of repairs is typically pretty extensive. It will also hide electrical wiring, making it difficult to perform maintenance and repairs in the future.
We also do not recommend this insulation be sprayed all over the crawl space walls. Although it does a great job of sealing existing cracks and small holes, it will also cover up any future cracks in the walls, which may be a sign of a larger and more serious issue. Another drawback to foam insulation is that if there is any moisture in the masonry wall when it is applied, it may not adhere properly and end up falling off the wall. We do use spray foam in small amounts to seal air vents when performing a crawl space encapsulation. It is excellent at preventing any air leaks around these spaces.
Can You Use Foam Insulation Boards in a Crawl Space?
Rigid foam insulation boards are the third type of insulation material. These foam panels are made from polyisocyanurate or a form of polystyrene, and offer up to twice the insulating power of other materials of the same thickness. (Source: energy.gov)
Foam board insulation can be applied to crawl space walls and provide good insulation even when the space is not encapsulated, but for maximum effectiveness, we always recommend a full encapsulation with a dehumidifier. These panels can be tricky for a DIY project, as they must completely cover the walls and the seams must be taped to insulate properly. They are also quite expensive.
So What is the Best type of Insulation for Crawl Spaces?
Ensuring that your home is properly insulated will reduce your energy bills and make your home more comfortable season to season. Using the correct insulation for each area of your home, especially in your crawl space, will maximize its effectiveness and offer cost savings in the long run. We find that the affordability and ease of installation of fiberglass batt makes it the best choice for crawl space insulation when a full encapsulation is performed.