DIY: Adding Insulation to a Crawlspace

When considering the idea of adding insulation to a crawlspace, doing the work safely and efficiently should be one of the first things to consider. This area of the dwelling, generally found in older homes and those with antique architecture, is usually about a foot high and may contain pipes, wiring, unused household goods plus other items, and is only large enough for a person to crawl through, hence the name. When looking to add crawlspace insulation to a dwelling there are a number of things that need consideration. Local regulations and building codes, type of construction of the dwelling, geographic location and climate, and the fact that many are not ventilated, will help in deciding what insulation would be the most suitable. There are a number of varieties to choose from, and all have an R-value. The R-value means heat flow resistance and measures the quality of the insulating effect. Choosing the right one for your situation will depend on the crawl space in your home and your budget.

One of the crawlspace insulation varieties is liquid polyurethane foam sprays. There are two types of these foams and these are a closed-cell spray and the other an open-cell spray. Both have differences and these may lead to advantages or disadvantages depending on the application requirements, so choosing the right one is important. These sprays are extremely versatile, materials with the closed-cell having very high insulating properties, an effective air barrier, low moisture penetration, a high resistance to water, and is identified for its hardness and strength. The open-cell type has an R-value slightly above half of the closed-cell variety, but still has a very good air barrier and thermal insulation. It doesn't ward off moisture vapor as well, has a spongier appearance with lower rigidity and strength, but has twice the sound barrier of the closed-cell type.

Further varieties of crawlspace insulation are foam boards or structural insulated panels. These consist of two pieces of structural board which may be plywood, sheet metal, oriented strand board or wafer board, and drywall which acts as a sandwich with extruded polystyrene foam, expanded polystyrene foam, compressed wheat straw or polyurethane foam enclosed between the two pieces. These are rigid, have a good insulating effect, moisture protection, less thickness and a good R-value. Fiber batts are another type of insulation these may take the form of pre-cut batts or a continuous blanket roll. There are a number of materials used in the manufacturer of these products which may include fiberglass, high-density fiberglass, rock and slag wool, plastic fiber, natural fiber plus a number of other products. The batts may not insulate as well as other products due to the gaps the batts may leave when installed, this is sometimes corrected using the blanket roll to cover these spaces. Because crawlspaces may vary between houses it may be wise to talk to an expert to determine the most suitable product for your project.