What is an R Value?




The R-value (resistance value) is the rating of a material's resistance to the flow of heat. The resistance depends upon a given material's thickness and density. The overall rating may be different for ceilings as opposed to walls, depending upon how the heat flows through the structural materials, such as studs and joists, onto which the spray foam is applied. The amount of R-value required depends upon the climate where the insulation is applied. The more insulation is applied, the greater the resistance or R-value. For proper spray foam R-value installation, consult your local building codes or material supplier. It is important to consider that compressed insulation tends to lose its full R-value because its thickness is reduced. So, proper installation is the key to maintaining the appropriate R-value. When calculating multi-layered insulation, simply add the individual layers together.


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