Minimum Insulation In Roof

See the department of energy s doe ranges for recommended levels of insulation below.

Minimum insulation in roof.

Less than the prescriptive r value at per foot slope as long as the system r value meets or exceeds that. Minimum insulation r value requirements by state. Minimum insulation r value requirements non residential above roof deck. Add insulation to attic.

Non residential above roof deck this matrix provides the minimum insulation r values required by local and state municipalities. Existing 3 4 inches of insulation. Achieving a u value of 0 20w m meaning your roof will be better insulated than your walls will need 120mm thickness of rigid foam or 200mm of mineral wool or natural insulation. Hitting amazing levels of 0 13w m will need 300mm of mineral wool or 180mm of rigid foam.

Recommended insulation levels for retrofitting existing wood framed buildings. Adhered bituminous membrane minimum requirements adhered single ply membrane minimum requirements see notes below for required perimeter and corner enhancements2 3 2 3see notes below for required perimeter and corner enhancements insulation type thickness 4 x 4 4 x 8 insulation type thickness 4 x 4 4 x 8. There is an exception provided that allows the minimum thickness to be up to 1. 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.