Roof R Value

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

Roof r value.

Here are the r values of the most popular commercial roofing systems. A material s r value is the measure of its resistance to heat flow. To calculate the total r value of a roof assembly find the total thickness in inches of each type of insulating material within the system. It is important to know the r value because many states or regions require that a roof system have a minimum amount of thermal resistance on commercial industrial and or institutional buildings.

Insulation level are specified by r value. The following table provides typical r values and rsi for various materials these r values were taken from manufacturer technical data sheets and are the reported r values per inch of actual products. The table below shows what levels of insulation are cost effective for different climates and locations in the home. The average r value for some common roof materials include.

The higher the r value the better the thermal performance of the insulation. 0 24 per inch of thickness. Higher r value means greater insulation performance and thus more savings on your next heating and cooling bill. The terminology average r value for tapered systems is an outdated term and not recognized by the iecc.

0 34 per inch of thickness. Recommended home insulation r values. I calculate insulation resistance to heat loss or r percentage improvement always as relative to the original number. 6 6 per inch of thickness.

The increase r21 r3 exactly 18 the value by which you are increasing the r value. The higher the r value the more the material insulates. R value measures how well building insulation can prevent the flow of heat into and out of the home. To learn more about r value see roof online s r value page.

For each different material multiply the thickness by the standard r value per inch for that material. 0 33 per inch of thickness. 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. 0 00 per inch of thickness.

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. This guide will teach you everything you need to know about insulation r values so you can better insulate your home. Add the results for all the materials together to get the total r value for the roof assembly. The percentage increase increase increase original number 100.

There is an exception provided that allows the minimum thickness to be up to 1 less than the prescriptive r value at per foot slope as long as the system r value meets or exceeds that prescriptive r value. R3 r18 r21 total roof r value.