Minimum Attic 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.

Minimum attic r value.

R value measures how well certain building insulation materials can resist heat. Existing 3 4 inches of insulation. In general to optimally isolate an attic on average an r value of the insulation is required ranging from r 50 to r 60. In zone 1 the average minimum requirement for attic insulation is 9 inches of r30 fill.

The average recommended level is 17 inches of r60. What is insulation r value. Add insulation to attic. To achieve a higher attic insulation r value another layer of insulation needs.

Recommended insulation levels for retrofitting existing wood framed buildings. 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. I m in georgia iecc climate zone 3 where our current state code requires r 13 in exterior walls r 18 in attic kneewalls r 19 in floors and r 30 in ceilings. The further north northeast you go the colder it is and the more necessary r value will grow.

Find out why in the seller s fact sheet on r values. Know exactly how much you need with our project calculators. R value is an efficiency rating for insulation. However this value varies not only on the basis of the type of insulating material but also on the area.

R values for walls represent the sum of cavity insulation plus insulated sheathing if any. 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. The second r value for mass walls applies when more than half the insulation is on the interior of the mass wall.

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. See the department of energy s doe ranges for recommended levels of insulation below. When determining how much insulation you need don t guesstimate calculate. If we put ducts in unconditioned space they have to be insulated to either r 8 if they re in an unconditioned attic or r 6 in any other type of unconditioned space.

The higher the value the more insulating ability the product has. The higher the r value the greater the insulation performance. Insulation r values are minimum acceptable levels and must be determined according to ftc rule. How much insulation in attic for zones 1 4.

In zone 2 the average minimum requirement for attic insulation is 9 inches of r30 fill.