Roof Insulation R Value Chart

Conditioned per atsm c1289 test method astm c5181 2.

Roof insulation r value chart.

R value is used in the united states. Rsi r value système international is the metric equivalent. 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. 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 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. To convert the r value of a specific thickness of a material to rsi divide the r value by 5 67826. R3 r18 r21 total roof r value. 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.

R value of various materials. You should of course see the manufacturer provided technical data sheet for the r value of specific products. R value chart for enerfoil tm rigid foam faced insulation. As a benchmark one inch of solid wood has an r value of 1.

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. See the department of energy s doe ranges for recommended levels of insulation below. Here s a handy r value table that covers most types of roof coverings building insulation and a few other materials.

The percentage increase increase increase original number 100. For a very good introductory overview article on r value see r values over at the website of. I calculate insulation resistance to heat loss or r percentage improvement always as relative to the original number. For example two inches of extruded polystyrene with an r value of 11 has an rsi of 1.

R value is a measure of insulation s ability to resist heat traveling through it. The table below shows what levels of insulation are cost effective for different climates and. The increase r21 r3 exactly 18 the value by which you are increasing the r value. To convert rsi to r value multiply the rsi by 5 67826.

Recommended home insulation r values. Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation.