Attic Insulation R Value Code

Achieving greater r values in exterior walls.

Attic insulation r value code.

Insulation level are specified by r value. For example if you have a type of insulation that has an r value of r 5 per inch of thickness you will need a depth of 6 inches of this insulation installed your attic to reach r 30 if you live in zones 2 or 3. For an attic the you could have an r 38 to meet the insulation code guidelines. In general to optimally isolate an attic on average an r value of the insulation is required ranging from r 50 to r 60.

The higher the r value the better the thermal performance of the insulation. The table below shows what levels of insulation are cost effective for different climates and. Energy star states that an r 60 is equal to the best performing attic insulation. 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 international codes i codes are the widely accepted comprehensive set of model codes used in the us and abroad to help ensure the engineering of safe sustainable affordable and resilient structures. However if an r 38 was enough customers wouldn t ask why they re still too cold or hot in their home. The higher the r value the better the thermal performance of the insulation. If structural sheathing covers 40 or less of the exterior continuous insulation r value shall be permitted to be reduced by no more than r 3 in the locations where structural sheathing is used.

You can achieve better thermal performance in your attic by adding an additional layer of insulation. You will need a higher r value of insulation if you live in the northeast than if you live in southern california. Where you live different climates require different insulation r values. Dte energy and consumers energy suggest an r 49 or above to be energy efficient.

Recommended home insulation r values. R value is a measure of insulation s ability to resist heat traveling through it. Your home s age if your home is more than 10 year old you likely need more insulation. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation.

The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process. There are many ways to retrofit a home with fiberglass and. 2015 code requires walls to be insulated with a minimum of r 20 or r 13 5 13 5 means r 13 cavity insulation plus r 5 insulated sheathing.