What is the R-Value of a 2x6 Wall with Spray Foam Insulation?

When it comes to insulation, the R-value of the entire wall is what really matters, not just the insulation itself.

Spray foam

is a popular choice for insulation, and it comes in two varieties: open-cell and closed-cell. Open-cell spray foam has an R-value of approximately R-3.7 per inch, while closed-cell spray foam has a much higher R-value of R-6.5 to R-7 per inch. Other less effective insulators, such as cellulose, fiberglass, or even open-cell foam, have R-values ranging from R-3.2 to R-3.8 per inch.

In southwestern Michigan, a 2 x 4-inch wall with open-cell foam doesn't meet the standards, unless rigid foam is used somewhere in the mix. The formation of thermal bridges through the 2 x 6 inch wall studs tends to detract from the use of spray foam between the studs, so cellulose insulation is recommended instead. Closed-cell foam also increases the structural strength of a roof, wall, or roof due to its glue-like density and adhesion. If you're insulating the inside of a basement wall, closed-cell spray foam makes more sense than open-cell spray foam. Closed-cell foam insulation with a high R-value per inch between the posts will give you the full value of your investment.

When open-cell spray foam insulation is installed at the bottom of the OSB roof coating, the coating sometimes gets wet. Open-cell spray foam installers will completely fill a 3.5-inch-deep cavity, allowing the foam to expand until it is proud of the uprights. The wooden structure required for spray foam insulation is the same as that required for standard construction or for an advanced-structure wall, depending on the structure strategy used. If you're considering re-insulating your home, chances are you've come across spray foam insulation as an option. It is expected that by the end of September the OSB will be completely dry (I don't want to spray the foam on it now).

The proportions of the R-value from an article about rigid insulation and sponge insulation also apply to the minimum thickness of a closed-cell spray foam layer.

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