Which Insulation Material Is Best for Crawl Spaces?

To help reduce your high electricity bills, there are many different types of insulation you can put around your crawl space. The kind of material you choose is very important because not all materials are suitable for all parts of the house. The most common materials used for insulation are fiberglass, foam, and cellulose. These materials are often used as insulation for homes, but whether they’re good for crawl spaces or not is a completely different story. 

When considering a material to use as insulation for your crawl space, the things you should consider are how absorbent it is and its R-value. The R-value of an insulation material rates how well it’s able to keep heat from going in and out of a space. Northern states like Minnesota and North Dakota need insulation materials with high R-values because of the extreme continental climate. 

• Problematic Insulation Material 

Fiberglass is an absorbent insulation material made of extremely fine glass. It is commonly used in homes, but it would not work well in a crawl space. Fiberglass retains heat in a space by absorbing it, but it also absorbs and retains moisture. This moisture eventually ends up damaging the material and weakening it. Cellulose is made of paper fiber and is a lot better for thermal control, but it’s still absorbent and, like fiberglass, would not be a good fit for humid areas like crawl spaces. 

Foam insulation is not absorbent and does not retain water. The problem with this kind of insulation for your crawl space comes with its R-value. Foam insulation usually has an R-value of 7 per inch. It’s more than fiberglass and cellulose, which have an R-value of 2.2-2.8 and 3.1-3.8 respectively, but it’s still not enough for what’s needed in Sioux Falls, SD, or Minneapolis, MN. 

• Recommended Insulation Material 

The best insulation material for a crawl space is a waterproof, reflective insulation material. As the name suggests, reflective material reflects heat off itself and keeps the air of an area still and warm. Materials like polystyrene are waterproof and have fantastic thermal properties. On its own, polystyrene has an R-value of 3.6 to slightly above 4 and it does not retain water. 

Our ExTremeBloc™ Crawl Space Insulation has a polystyrene core with a reflective surface. It’s embedded with graphite particles that help the panels reflect heat, raising the R-value to 11. This superior kind of insulation material is exactly what you need to stop the stack effect from raising your energy bills.