Fiberglass Attic Insulation R Value

The higher the r value the better the thermal performance of the insulation.

Fiberglass attic insulation r value.

This calculator is to be used as an estimating tool only. The loss of r value started at a temperature difference of about 32 f. In fact the loose fill fiberglass lost 35 to 50 of its resistance to heat flow at temperature differences of 70 f to 76 f. R value is a measure of insulation s ability to resist heat traveling through it.

Input depth of existing blown in insulation in inches. You can achieve better thermal performance in your attic by adding an additional layer of insulation. Warmer climates only require an r 38 or higher or about 12 or more. Depending on where you live it s recommended that attics have a minimum r value of r 30 in warm climates to r 60 in cold climates.

Click the button to calculate the approximate r value for this job. As you can see there s some variation in r value depending on the particular type and brand of products used. If it s a new building simply reference the energy code map. In comparison an inch of blown fiberglass insulation has an r value of 3 1 3 4 and an inch of blown cellulose in an attic has an r value of 3 2 3 7.

Insulation level are specified by r value. If the attic is already insulated you ll want to check the current r value. Recommended home insulation r values. It can be located on a card left by the previous installer printed on the attic insulation or you can measure it yourself.

The loose fill fiberglass showed a significant reduction in r value as the attic got colder and the temperature difference got larger. The table below shows what levels of insulation are cost effective for different climates and. R value is a measurement of thermal resistance and measures the ability of heat to transfer from one side of an object to another. First you ll need to determine your r value.

The higher the r value the better the thermal performance of the insulation.