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Select a state and county to view its minimum insulation requirements.

Visit the Status of State Energy Codes website to see if Connecticut has adopted the 2009 IECC.

Climate Zone 5 & 4 Marine

Ceiling R-value38
Wood Frame Wall R-value 20 or 13+5h
Mass Wall R-value i 13/17
Floor R-value 30g
Basement Wall R-value c 10/13
Slab R-value d, Depth 10, 2 ft
Crawlspace Wall R-value c 10/13
Fenestration U-Factor b 0.35
Skylight U-Factor b 0.60
Glazed fenestration SHGC b, e NR

a. R-values are minimums. U-factors and SHGC are maximums. R-19 batts compressed into a nominal 2x6 framing cavity such that the R-value is reduced by R-1 or more shall be marked with the compressed batt R-value in addition to the full thickness R-value.

b. The fenestration U-factor column excludes skylights. The SHGC column applies to all glazed fenestration.

c. "15/19" means R-15 continuous insulated sheathing on he interior or exterior of the home or R-19 cavity insulation at the interior of the basement wall. "10/13" means R-10 continuous insulated sheathing on the interior or exterior of the home or R-13 cavity insulation at the interior of the basement wall.

d. R-5 shall be added to the required slab edge R-values for heated slabs. Insulation depth shall be the depth of the footing or 2 feet, whichever is less in zones 1 through 3 for heated slabs.

e. There are no SHGC requirements in the Marine zone.

f. Basement Wall Insulation is not required in warm-humid locations.

g. Or insulation sufficient to fill the framing cavity. R-19 is minimum.

h. "13+5" means R-13 cavity insulation plus R-5 insulated sheathing. If structural sheathing covers 25 percnt or less of the exterior, insulating sheathing is not required where structural sheathing is used. If structural sheathing covers more than 25 percent of exteriror, structural sheathing shall be supplemented with insulated sheathing of atleast R-2.

i. The second R-value applies when more than half the insulation is on the interior of the wall.

j. For impact rated fenestration complying with SectionR301.2.1.2 of the International Residential Code or Section 1608.1.2 of the International Building code, the maximum U-factor shall be 0.75 in Zone 2 and 0.65 in Zone 3.