Fiberglass Attic Insulation R Value

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

Fiberglass attic insulation r value.

Input depth of existing blown in insulation in inches. The loss of r value started at a temperature difference of about 32 f. The loose fill fiberglass showed a significant reduction in r value as the attic got colder and the temperature difference got larger. If it s a new building simply reference the energy code map.

The higher the r value the better the thermal performance of the insulation. Click the button to calculate the approximate r value for this job. Recommended home insulation r values. 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. First you ll need to determine your r value. 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. If the attic is already insulated you ll want to check the current r value.

R value is a measurement of thermal resistance and measures the ability of heat to transfer from one side of an object to another. 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. This calculator is to be used as an estimating tool only. 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 table below shows what levels of insulation are cost effective for different climates and. R value is a measure of insulation s ability to resist heat traveling through it. Achieving greater r values in exterior walls.

As you can see there s some variation in r value depending on the particular type and brand of products used.