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 in roof.

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. Recognized by the iecc. State applicable energy ashrae zone minimum r value state local ms mississippi ashrae 90 1 2010 2 r 20 3 r 20 state local mo missouri 2012 iecc 4 r 25 5 r 25 state only mt montana 2012 iecc 6 r 30. See the department of energy s doe ranges for recommended levels of insulation below.

Zone 6 requires an r 30 minimum which is 5 2 thick. Hitting amazing levels of 0 13w m will need 300mm of mineral wool or 180mm of rigid foam. Minimum insulation r value requirements by state. There is an exception provided that allows the minimum thickness to be up to 1.

Existing 3 4 inches of insulation. Recommended insulation levels for retrofitting existing wood framed buildings. Minimum insulation r value requirements non residential above roof deck. 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.