Roof Insulation R Value Chart

Here s a handy r value table that covers most types of roof coverings building insulation and a few other materials.

Roof insulation r value chart.

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. 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. I calculate insulation resistance to heat loss or r percentage improvement always as relative to the original number. See the department of energy s doe ranges for recommended levels of insulation below.

For a very good introductory overview article on r value see r values over at the website of. Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation. R3 r18 r21 total roof r value. 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. Recommended home insulation r values. R value is used in the united states.

Thickness inches r value in i p imperial rsi r value in metric 0 5. Insulation level are specified by r value. You should of course see the manufacturer provided technical data sheet for the r value of specific products. For example two inches of extruded polystyrene with an r value of 11 has an rsi of 1.

As a benchmark one inch of solid wood has an r value of 1. R value of various materials. The table below shows what levels of insulation are cost effective for different climates and. To convert rsi to r value multiply the rsi by 5 67826.

The percentage increase increase increase original number 100. Rsi r value système international is the metric equivalent. R value is a measure of insulation s ability to resist heat traveling through it. R value chart for enerfoil tm rigid foam faced insulation.

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.