Minimum R Value For Attic

Insulation r values are minimum acceptable levels and must be determined according to ftc rule.

Minimum r value for attic.

R value is a measure of insulation s ability to resist heat flow. Know exactly how much you need with our project calculators. 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. The higher the r value the better the thermal performance of the insulation.

The second r value for mass walls applies when more than half the insulation is on the interior of the mass wall. The higher the r value the better the thermal performance of the insulation. Usually the recommended r value for attics varies between r 40 and r 80 depending on the area province and climate. 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 recommended level for most attics is to insulate to r 38 or about 10 to 14 inches depending on insulation type. R value is a measure of insulation s ability to resist heat traveling through it. Consequently the thickness which fluctuates according to the type of insulating material must be suitable to meet the needs of r value. R value measures how well certain building insulation materials can resist heat.

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. 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. Insulation level are specified by r value.

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. R values for walls represent the sum of cavity insulation plus insulated sheathing if any. 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 higher the r value the greater the insulation performance.

The average recommended level is 14 inches of r49. In zone 1 the average minimum requirement for attic insulation is 9 inches of r30 fill.