Ever Wonder What an Insulation R-Value Means? R-value measures how strongly an insulation material resists heat flow . The higher the R-value of your insulation, the better it slows heat moving in or out of a building. Essentially, the higher the number, the better it performs. For spray polyurethane foam, there are two forms to consider: open-cell foam is typically around R-3.5 to R-3.7 per inch, while closed-cell spray foam is typically around R-6 to R-7 per inch, dependin
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