Roof Insulation R Value Chart

The increase r21 r3 exactly 18 the value by which you are increasing the r value.

Roof insulation r value chart.

R3 r18 r21 total roof r value. For a very good introductory overview article on r value see r values over at the website of. Rsi r value système international is the metric equivalent. 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.

For example two inches of extruded polystyrene with an r value of 11 has an rsi of 1. Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation. As a benchmark one inch of solid wood has an r value of 1. To convert the r value of a specific thickness of a material to rsi divide the r value by 5 67826.

R value is a measure of insulation s ability to resist heat traveling through it. R value of various materials. 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. The table below shows what levels of insulation are cost effective for different climates and.

See the department of energy s doe ranges for recommended levels of insulation below. 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. R value chart for enerfoil tm rigid foam faced insulation. Thickness inches r value in i p imperial rsi r value in metric 0 5.

I calculate insulation resistance to heat loss or r percentage improvement always as relative to the original number. Here s a handy r value table that covers most types of roof coverings building insulation and a few other materials. Insulation level are specified by r value. 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. Recommended home insulation r values. You should of course see the manufacturer provided technical data sheet for the r value of specific products. The higher the r value the better the thermal performance of the insulation.

To convert rsi to r value multiply the rsi by 5 67826. Conditioned per atsm c1289 test method astm c5181 2.