R30 Roof Insulation Thickness

Wall insulation whenever exterior siding is removed on an.

R30 roof insulation thickness.

Fiberglass panels and rolls with an r 30 insulation value have a typical thickness of eight to nine and a half inches. Insulation thickness to reach the r 30 value depends on the insulation material but fiberglass batts of r 30 insulation are 9 1 2 inches thick. Typical recommendations for exterior walls are r 13 to r 23 while r 30 r 38 and r 49 are common for ceilings and attic spaces. Rated r value and thickness of insulation r value r6 r11.

As a foil faced polyisocyanurate foam insulation enerfoil tm s r value actually more than doubles. R 30 insulation thickness or even r 19 thickness is often used in warmer climates. Rigid foam insulation provides the same r factor with approximately one half the thickness. The thickness of r 30 insulation varies depending on the type of insulation used.

Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation. Note that r30 batt insulation thickness is just 9 1 2 inches thick where as r 49 batt insulation thickness is 15 1 2 inches. Professional should specify insulation thickness based r value on the 6 0 r inch design guideline associated with the old lttr test method. Likewise for jobs that will be permitted in 2014 the design professional should specify insulation thickness based on the 5 7 r inch design guideline associated with the new lttr test method.

Eight inches of poor quality insulation may have a higher and better r value than one inch of top quality insulation. So you need to know an insulation product s thickness as well as its r value in order to compare it to another product. See the department of energy s doe ranges for recommended levels of insulation below. This is a significant difference and thus why r 49 batt insulation is used typically in colder climates.