Minimum R Value For Attic

The higher the r value the better the thermal performance of the insulation.

Minimum r value for attic.

Recommended home insulation r values. Under insulated here means when compared to the minimum prescriptive wall and ceiling insulation r values found in the 2006 international energy conservation code iecc savings vary. The average recommended level is 14 inches of r49. 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 to maintain a consistent total sheathing thickness.

R value is a measure of insulation s ability to resist heat flow. 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. 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. In zone 2 the average minimum requirement for attic insulation is 9 inches of r30 fill.

Usually the recommended r value for attics varies between r 40 and r 80 depending on the area province and climate. The higher the r value the better the thermal performance of the insulation. Insulation level are specified by r value. R value measures how well certain building insulation materials can resist heat.

Consequently the thickness which fluctuates according to the type of insulating material must be suitable to meet the needs of r value. Know exactly how much you need with our project calculators. In zone 1 the average minimum requirement for attic insulation is 9 inches of r30 fill. 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.

Insulation r values are minimum acceptable levels and must be determined according to ftc rule. When determining how much insulation you need don t guesstimate calculate. R values for walls represent the sum of cavity insulation plus insulated sheathing if any. With an r value of 4 0 to 5 1 per inch depending on the manufacturer pre expanded injection foam provides a higher r value than fiberglass or cellulose and it seals the building from air leakage at the same time.

The second r value for mass walls applies when more than half the insulation is on the interior of the mass wall. The recommended level for most attics is to insulate to r 38 or about 10 to 14 inches depending on insulation type.