Fiberglass Attic Insulation R Value

Warmer climates only require an r 38 or higher or about 12 or more.

Fiberglass attic insulation r value.

If it s a new building simply reference the energy code map. R value is a measurement of thermal resistance and measures the ability of heat to transfer from one side of an object to another. This calculator is to be used as an estimating tool only. You can achieve better thermal performance in your attic by adding an additional layer of insulation.

The higher the r value the better the thermal performance of the insulation. Houses in a cold climate should have a minimum of r 49 in the attic which is equivalent to approximately 16 of fiberglass insulation. The loose fill fiberglass showed a significant reduction in r value as the attic got colder and the temperature difference got larger. 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.

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. The table below shows what levels of insulation are cost effective for different climates and. The higher the r value the better the thermal performance of the insulation. If the attic is already insulated you ll want to check the current r value.

Achieving greater r values in exterior walls. Click the button to calculate the approximate r value for this job. 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. As you can see there s some variation in r value depending on the particular type and brand of products used.

Input depth of existing blown in insulation in inches. Recommended home insulation r values. Insulation level are specified by r value. First you ll need to determine your r value.

As a benchmark one inch of solid wood has an r value of 1.