2009-2021 IECC and IRC Minimum Insulation Requirements for New Homes

Description

This table is adapted from Table R402.1.1 in the 2009 and 2012 International Energy Conservation Code (IECC), which is Table R402.1.2 in the 2015 and 2018 IECC, and Table R402.1.3 in the 2021 IECC, as well as Table N1102.1 in the 2009 International Residential Code (IRC), Table 1102.1.1 in the 2012 IRC, Table N1102.1.2 in the 2015 and 2018 IRC, and Table N1102.1.3 in the 2021 IRC.

 

Climate
 Zone

Ceiling
 R-Value

Wood Frame Wall R-Value

Mass Wall
R-Value
i*

Floor
R-Value

Basement c Wall
 R-Value

Slab d R-Value & Depth

Crawl Space Wall
R-Value
c, h

 

2009 IECC

2012
2015

2018

IECC

2021 IECC

2009 IECC

2012
2015

2018

IECC

2021 IECC h

2009 IECC k

2012
2015

2018 2021

IECC

2009 IECC

2012
2015

2018 2021

IECC

2009 IECC

2012
2015

2018

IECC

2021 IECC

2009 IECC

2012
2015

2018

IECC

2021 IECC

2009 IECC

2012
2015

2018

IECC

2021 IECC

1

30

30

30

13

13

13 or 0+10ci

3/4

3/4

13

13

0

0

0

0

0

0

0

0

0

2

30

38

49

13

13

13 or 0+10ci

4/6

4/6

13

13

0

0

0

0

0

0

0

0

0

3

30

38

49

13

20 or 13+5h

20 or 13+5ci or 0+15

5/8

8/13

19

19

5/13f

5/13f

5ci or 13f

 

0

0

10ci, 2ft

5/13

5/13

5ci or 13f

4 except Marine

38

49

60

13

20 or 13+5h

30 or 20+5ci or 13+10ci or 0+20ci

5/10

8/13

19

19

10/13

10/13

10ci or 13

10,
2 ft

10,
2 ft

10ci, 4ft

10/13

10/13

10ci or 13

5 and Marine 4

38

49

60

20 or 13+5h

20 or 13+5h

30 or 20+5ci or 13+10ci or 0+20ci

13/17

13/17

30g

30g

10/13

15/19

15ci or 19 or 13+5ci

10,
2 ft

10,
2 ft

10ci, 4ft

10/13

15/19

15ci or 19 or 13+5ci

6

49

49

60

20 or 13+5h

20+5h or 13+10h

30 or 20+5ci or 13+10ci or 0+20ci

15/19

15/20

30g

30g

15/19*
IRC: 10/13

15/19

15ci or 19 or 13+5ci

10,
4 ft

10,
4 ft

10ci, 4ft

10/13

15/19

15ci or 19 or 13+5ci

7 and 8

49

49

60

21

20+5h or 13+10h

30 or 20+5ci or 13+10ci or 0+20ci

19/21

19/21

38g*

IRC: 30g

38g

15/19*

IRC: 10/13

15/19

15ci or 19 or 13+5ci

10,
4 ft

10,
4 ft

10ci, 4ft

10/13

15/19

15ci or 19 or 13+5ci

For SI: 1 foot = 304.8 mm. NR = not required.  Ci = continuous insulation.

*The IRC code requirement differs from the IECC code requirement, as noted. 

  1. Table adapted from Table R402.1.1 in the 2009 and 2012 IECC and Table R402.1.2 in the 2015 and 2018 IECC (Table N1102.1 in 2009 IRC, Table 1102.1.1 in 2012 IRC, and Table N1102.1.2 in 2015 and 2018 IRC).
    2012, 2015, 2018, and 2021 IECC: R-values are minimums. Where insulation is installed in a cavity that 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.

2009 IECC: R-values are minimums. 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.

  1. Refers to fenestration requirements not shown on this excerpted table.
  2. 2021 IECC: “5ci or 13” means R-5 continuous insulation (ci) on the interior or exterior surface of the wall or R-13 cavity insulation on the interior side of the wall. “10ci or 13” means R-10 continuous insulation (ci) on the interior or exterior surface of the wall or R-13 cavity insulation on the interior side of the wall. “15ci or 19 or 13+5ci” means R-15 continuous insulation (ci) on the interior or exterior surface of the wall or R-19 cavity insulation on the interior side of the wall; or R-13 cavity insulation on the interior of the wall in addition to R-5 continuous insulation on the interior or exterior of the wall.       

2009-2018 IECC: “10/13” means R-10 continuous insulation (called “insulated sheathing” in 2009 IECC) on the interior or exterior of the home or R-13 cavity insulation at the interior of the basement wall. “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. Alternatively, compliance with “15/19” shall be R-13 cavity insulation on the interior of the basement wall plus R-5 continuous insulation on the interior or exterior of the home.

2009 IRC Only: The first R-value applies to continuous insulation, the second to framing cavity insulation; either insulation meets the requirement.

  1. 2018 and 2021 IECC: R-5 insulation shall be provided under the full slab area of a heated slab in addition to the required slab edge insulation R-value for slabs, as indicated in the table. The slab edge insulation for heated slabs shall not be required to extend below the slab.
    2009, 2012, and 2015 IECC: 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.
  2. Refers to fenestration requirements not shown on this excerpted table.
  3. 2009-2021 IECC: Basement wall insulation is not required in warm-humid locations as defined by Figure R301.1 and Table R301.1 (Figure/Table N1101.2 in 2009 IRC and Figure/Table N1101.10 in 2012, 2015, and 2018 IRC).
  4. 2009-2018 IECC: Alternatively, insulation sufficient to fill the framing cavity and providing not less than an R-value of R-19.
  5. 2015, 2018, 2021 IECC: The first value is cavity insulation; the second value is continuous insulation. Therefore, as an example, “13+5” means R-13 cavity insulation plus R-5 continuous insulation. (This is labeled footnote “g” in the 2021 IECC.)
    2012 IECC: First value is cavity insulation, second value 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% or less of the exterior, continuous insulation R-value shall be permitted to be reduced by no more than R-3 in the locations where structural sheathing is used – to maintain a consistent total sheathing thickness.
    2009 IECC: “13+5” means R-13 cavity insulation plus R-5 insulated sheathing. If structural sheathing covers 25% or less of the exterior, insulating sheathing is not required where structural sheathing is used. If structural sheathing covers more than 25% of exterior, structural sheathing shall be supplemented with insulated sheathing of at least R-2.
  6. 2018, 2021 IECC: Mass walls shall be in accordance with Section R402.2.5 (N1102.2.5 in 2018 IRC). The second R-value applies when more than half of the insulation is on the interior of the mass wall. (This is labeled footnote “h” in the 2021 IECC.)
    2009, 2012, and 2015 IECC: The second R-value applies when more than half of the insulation is on the interior of the mass wall. (In 2009 IRC, this is footnote k and footnotes i and j refer to fenestration values not shown in this table.)
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