Roof Insulation R Value Chart

R value chart for enerfoil tm rigid foam faced insulation.

Roof insulation r value chart.

Recommended home insulation r values. I calculate insulation resistance to heat loss or r percentage improvement always as relative to the original number. Rsi r value système international is the metric equivalent. You should of course see the manufacturer provided technical data sheet for the r value of specific products.

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 is a measure of insulation s ability to resist heat traveling through it. 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. Thickness inches r value in i p imperial rsi r value in metric 0 5.

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. For example two inches of extruded polystyrene with an r value of 11 has an rsi of 1. R value of various materials.

The higher the r value the better the thermal performance of the insulation. For a very good introductory overview article on r value see r values over at the website of. 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. The increase r21 r3 exactly 18 the value by which you are increasing the r value.

Here s a handy r value table that covers most types of roof coverings building insulation and a few other materials. See the department of energy s doe ranges for recommended levels of insulation below. Insulation level are specified by r value. R3 r18 r21 total roof r value.

To convert the r value of a specific thickness of a material to rsi divide the r value by 5 67826. To convert rsi to r value multiply the rsi by 5 67826. 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. The table below shows what levels of insulation are cost effective for different climates and.

Conditioned per atsm c1289 test method astm c5181 2. 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.