Attic Insulation Thickness R Value

Insulation level are specified by r value.

Attic insulation thickness r value.

Foam in place insulation can be blown into walls on attic surfaces or under floors to insulate and reduce air leakage. See the department of energy s doe ranges for recommended levels of insulation below. Insulation levels are specified by r value. The higher the r value the better the thermal performance of the insulation.

Along with knowing the r value of a particular insulation it is also important to calculate the r value of a total system. The r value depends on the type of insulation its thickness and its density. The higher the r value the better the thermal performance of the insulation. The recommended level for most attics is to insulate to r 38 or about 10 to 14 inches depending on insulation type.

When calculating the r value of a multilayered installation add the r values of the individual layers. You will need a higher r value of insulation if you live in the northeast than if you live in southern california. R value is a measure of insulation s ability to resist heat traveling through it. You can achieve better thermal performance in your attic by adding an additional layer of insulation.

Spray foam pink fiberglas vs. 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. As a benchmark one inch of solid wood has an r value of 1. Add the right kind of insulation.

The higher the r value the better the thermal performance of the insulation. Meaning if you use a tight air seal you don t need to use as high of a total r value. Some installations can yield a higher r value than traditional batt insulation for the same thickness and can fill even the smallest cavities creating an effective air barrier. Recommended home insulation r values.

The r value of some insulations also depends on temperature aging and moisture accumulation. The table below shows what levels of insulation are cost effective for different climates and. There are many ways to retrofit a home with fiberglass and. 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.

You can use the small pressurized cans of foam. Your home s age if your home is more than 10 year old you likely need more insulation. Achieving greater r values in exterior walls. R value is a measure of insulation s ability to resist heat flow.

For example residential icc code 5 2 9 r806 5 for attic insulation says air impermeable insulation is not required to meet the r value minimum listed in the chart above.