Minimum Insulation In Roof

There is an exception provided that allows the minimum thickness to be up to 1.

Minimum insulation in roof.

Minimum insulation r value requirements by state. 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. 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. Less than the prescriptive r value at per foot slope as long as the system r value meets or exceeds that.

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. Recommended insulation levels for retrofitting existing wood framed buildings. Add insulation to attic. Minimum insulation r value requirements non residential above roof deck.

Existing 3 4 inches of insulation. 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. Non residential above roof deck this matrix provides the minimum insulation r values required by local and state municipalities. Recognized by the iecc.