With most types of insulation, as the temperature drops the R-value increases, but some perform much better than others. It is important that, when you compare the R-values of different insulations, you know at what temperature the product was tested. In the US, the apples-to-apples R-value standard is ASTM C518, and the test results are reported a temperature of 75°F. In colder climates where your heating costs are high, you might be more interested in the insulation's R-value at maybe 60°F or 40°F or maybe even 20°F. RAYCORE's custom blend high density closed cell polyurethane foam is the best performing insulator on the market for cold climates! Equally, it is a standout in hot climates as well!
5.5" Thick Headers For 2x6 Wall Applications.
R18 @ 50°F double LVL
7.25" Thick Headers For 2x8 Wall Applications.
R31 @ 50°F double LVL