Ceiling Insulation R Value Code

Add insulation to attic.

Ceiling insulation r value code.

Roof or insulation of r 15 if present attics above insulation are vented and attics below insulation unvented roof surface slope of not less than unit vertical in 12 units horizontal i e 1 48 or 2 1 code says 21 tropical zone. R 30 ceiling insulation may be used in place of r 37 if the insulation achieves the full r value over the entire ceiling area i e not compressed over exterior walls and including any access openings. Recommended insulation levels for retrofitting existing wood framed buildings. Existing 3 4 inches of insulation.

If designing to the pa alternative energy code there is no area limit on cathedral ceilings. 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. For example if you have a type of insulation that has an r value of r 5 per inch of thickness you will need a depth of 6 inches of this insulation installed in your attic to reach r 30 if you live in zones 2 or 3. 1 foot 304 8 mm.

See the department of energy s doe ranges for recommended levels of insulation below. These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation.