Roof Insulation R Value Chart

R value is a measure of insulation s ability to resist heat traveling through it.

Roof insulation r value chart.

To convert the r value of a specific thickness of a material to rsi divide the r value by 5 67826. See the department of energy s doe ranges for recommended levels of insulation below. For example a wall with 3 fiberglass batting r value of 10 8 11 9 may have an overall r value of nearly 14 because of siding sheathing and drywall. For example two inches of extruded polystyrene with an r value of 11 has an rsi of 1.

For a very good introductory overview article on r value see r values over at the website of. The table below shows what levels of insulation are cost effective for different climates and. Insulation level are specified by r value. Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation.

The higher the r value the better the thermal performance of the insulation. 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. Rsi r value système international is the metric equivalent. Here s a handy r value table that covers most types of roof coverings building insulation and a few other materials.

Recommended home insulation r values. Depending on where you live and the part of your home you re insulating walls crawlspace attic etc you ll need a different r value. R value of various materials. R3 r18 r21 total roof r value.

R value insulation chart find your zone on the map and then use the chart to determine the level of insulation you need to properly insulate your attic walls floors and crawlspaces. Conditioned per atsm c1289 test method astm c5181 2. I calculate insulation resistance to heat loss or r percentage improvement always as relative to the original number. 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.

Thickness inches r value in i p imperial rsi r value in metric 0 5. To convert rsi to r value multiply the rsi by 5 67826. Along with knowing the r value of a particular insulation it is also important to calculate the r value of a total system. The percentage increase increase increase original number 100.

R value is used in the united states. As a benchmark one inch of solid wood has an r value of 1.