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Spray Foam Insulation: The Types and Cost of Insulating your Home

Spray foam is a type of insulation usually applied on the walls, roofs and other areas with corners and contours to create an airtight barrier. Polyurethane is often used to make spray foam insulation. How much you spend on this insulation will depend on the type of spray foam used as well as the amount that is applied. There are two main types of spray foam: open cell and closed cell. Unlike other insulation materials like fiberglass, spray foam is easy to apply when construction is underway because it is expandable. It can also be sprayed on existing wall cavities.

Open cell spray foam insulation

The difference between open cell and closed cell spray foam insulation is in their R-value and density. Open cell spray foam insulation has a density of about 1/2lb per cubic foot. Its R-value is 3.5 to 3.6 per in. The R-value and density of the foam are directly proportional. This value indicates how well the material resists heat flow. Open cell spray foam has a lower R-value and density and is not resistant to vapor. If you choose this insulation in a space that requires high resistance such as the attic, it should be applied together with vapor retarding paint. Expect to pay about $2 to $7 per sq. ft. on open cell spray foam.


Closed cell spray foam insulation

Closed cell spray foam, on the other hand, has a higher density of 2lb per cubic ft. than its counterpart. Its R-value is about 6.5 per in. This type of insulating material is best suited for ceilings, walls, and roofs. When properly applied, this type of insulation gives an excellent barrier compared to any other available in the market. It’s suitable for inner walls as it can help repel moisture and enhance the strength of the wall structure with glue like tenacity. Due to its efficiency, closed cell spray foam insulation comes at a cost. You may spend about $2000 to install this type of insulation in your home.

Insulating a new home versus an existing home

The cost of insulating a finished house is likely to be more than a home that is being constructed. Newly constructed homes are considered to be the best candidates for spray foam insulation because it’s easy for the contractor to work effectively and ensure that the material is properly applied to minimize utility costs, heat transfer and offer optimal protection. On the other hand, if the spray foam is being installed in an existing home, it can cost more because it will require more time to be applied. The contractor may recommend an energy audit prior to installation, which costs more money.


A key decision that you’ll need to make during spray foam insulation is determining the R-value that’s best for your home. Don’t measure insulation through the R-value only because heat loss or gain can occur in many other ways. The best way to determine the effectiveness of insulation is by taking into account other forms of heat transfer such as conduction, radiation, convection and air infiltration which occurs in your home.