The insulation levels of an attic or of any part of a house are understood through the r value that is the value with which the insulating material is resistant to heat flow.
Attic insulation r value code.
Dte energy and consumers energy suggest an r 49 or above to be energy efficient.
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.
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.
These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation.
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.
The higher the r value the better the thermal performance of the insulation.
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.
Where using a simulated energy performance analysis sections of ducts that are installed in accordance with section 1103 3 6 located directly on or within 5 5 inches 140 mm of the ceiling surrounded with blown in attic insulation having an r value of r 30 or greater and located such that the top of the duct is not less than 3 5 inches 89.
You can achieve better thermal performance in your attic by adding an additional layer of insulation.
Energy star states that an r 60 is equal to the best performing attic insulation.
Where you live different climates require different insulation r values.
In general to optimally isolate an attic on average an r value of the insulation is required ranging from r 50 to r 60.
Insulation level are specified by r value.
You will need a higher r value of insulation if you live in the northeast than if you live in southern california.
Achieving greater r values in exterior walls.
The table below shows what levels of insulation are cost effective for different climates and.
The higher the r value the better the thermal performance of the insulation.
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.
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.
Recommended home insulation r values.
R value is a measure of insulation s ability to resist heat traveling through it.
For an attic the you could have an r 38 to meet the insulation code guidelines.
However if an r 38 was enough customers wouldn t ask why they re still too cold or hot in their home.
