Roof R Value

The terminology average r value for tapered systems is an outdated term and not recognized by the iecc.

Roof r value.

0 24 per inch of thickness. 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. 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. I calculate insulation resistance to heat loss or r percentage improvement always as relative to the original number.

Higher r value means greater insulation performance and thus more savings on your next heating and cooling bill. 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. 6 6 per inch of thickness. The way it works is simple.

A material s r value is the measure of its resistance to heat flow. Recommended home insulation r values. Insulation level are specified by r value. The table below shows what levels of insulation are cost effective for different climates and locations in the home.

R3 r18 r21 total roof r value. 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. 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.

Here are the r values of the most popular commercial roofing systems. The higher the r value the better the thermal performance of the insulation. This guide will teach you everything you need to know about insulation r values so you can better insulate your home. The increase r21 r3 exactly 18 the value by which you are increasing the r value.

0 00 per inch of thickness. 0 24 per inch of thickness. 0 34 per inch of thickness. 0 33 per inch of thickness.

To learn more about r value see roof online s r value page. R value measures how well building insulation can prevent the flow of heat into and out of the home. To calculate the r value of a roof system your contractor will take into account the underlayment coverboards adhesives insulation and even the membrane. For each different material multiply the thickness by the standard r value per inch for that material.

The average r value for some common roof materials include. 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.