2012 Residential Energy Efficiency

Source: IECC 2012 Table R402.1.1
Insulation and Fenestration Requirements by Component

Climate
Zone

Fenestration
U-Factorb

Skylight
U-Factorb

Fenestration
SHGCb,e

Ceiling
R-Value

Wood Frame
Wall R-Value

1

NR

0.75

0.25

30

13

2

0.40

0.65

0.25

38

13

3

0.35

0.55

0.25

38

20 or 13+5h

4 except Marine

0.35

0.55

0.40

49

20 or 13+5h

5 and Marine 4

0.32

0.55

NR

49

20 or 13+5h

6

0.32

0.55

NR

49

20+5 or 13+10h

7 and 8

0.32

0.55

NR

49

20+5 or 13+10h


Climate
Zone

Mass Wall
R-Valuei

Floor
R-Value

Basement Wall
R-Valuec

Slab R-Value
& Depthd

Crawl Space
Wall R-Valuec

1

3/4

13

0

0

0

2

4/6

13

0

0

0

3

8/13

19

5/13f

0

5/13

4 except Marine

13/17

19

10/13

10, 2 ft.

10/13

5 and Marine 4

15/20

30g

15/19

10, 2 ft.

15/19

6

19/21

30g

15/19

10, 4 ft.

15/19

7 and 8

19

38g

15/19

10, 4 ft.

15/19

For SI: 1 foot = 304.8 mm.

  • a. R-values are minimums. U-factors and SHGC are maximums. When insulation is installed in a cavity which is less than the label or design thickness of the insulation, the installed R-value of the insulation shall not be less than the R-value specified in the table.
  • b. The fenestration U-factor column excludes skylights. The SHGC column applies to all glazed fenestration. Exception: Skylights may be excluded from glazed fenestration SHGC requirements in Climate Zones 1 through 3 where the SHGC for such skylights does not exceed 0.30.
  • c. "15/19" means R-15 continuous insulation on the interior or exterior of the home or R-19 cavity insulation at the interior of the basement wall. "15/19" shall be permitted to be met with R-13 cavity insulation on the interior of the basement wall plus R-5 continuous insulation on the interior or exterior of the home. "10/13" means R-10 continuous insulation 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 Climate 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 as defined by Figure R301.1 and Table R301.1.
  • g. Or insulation sufficient to fill the framing cavity, R-19 minimum.
  • h. First value is cavity insulation, second is continuous insulation or insulated siding, so "13+5" means R-13 cavity insulation plus R-5 continuous insulation or insulated siding. If structural sheathing covers 40 percent or less of the exterior, continuous insulation R-value shall be permitted to be reduced by no more than R-3 in locations where structural sheathing is used - to maintain a consistent total sheathing thickness.
  • i. The second R-value applies when more than half the insulation is on the interior of the mass wall.