How does foam insulation compare to fiberglass or cellulose?
Foam insulation outperforms both fiberglass and cellulose insulation due to the simple fact that air infiltrates both fiberglass and cellulose. When this happens, the R-value of these inferior products can drop by as much as 50%. Because fiberglass and cellulose do not eliminate air infiltration, once air pass across these products, their R-value drops. Bottom line: Just because it’s rated an R-30, doesn’t mean it’s going to perform to an R-30. When products are tested for their R-value in a lab, it’s a static environment, meaning there is not air passing across or against the material. Ultimately, this is not how the home will ultimately function. Where you have penetrations in your exterior wall for windows, doors, sill plates, vents and hose bibs, you have air infiltration. Once that air hits fiberglass or cellulose, the R-value it was assigned at testing is inaccurate.
