Wood Step 1A: One- and Two-Family Dwellings (≤ 3 stories) – IRC Ch11/IECC-Residential | Continuous Insulation with Foam Sheathing

Determine your Climate Zone (see Figure 1 or Chapter 3 of the IECC-R)
For the prescriptive R-value recommendations, refer to Table 1 below.
For the prescriptive U-factor method to determine alternative R-value solutions for compliance, refer to the Wood Frame Wall Calculator.
For the Performance or Energy Rating Index compliance methods, refer to an energy modeling or energy rating professional to determine compliance.

TABLE 1
Wood-frame Wall Ci R-values for Energy Code Compliance¹
[One- and Two-Family Dwellings ≤ 3 stories]

CLIMATE ZONE	Minimum R-values (IECC-R or IRC Ch.11)	Recommended R-values²
1	13	0+10ci, 13+2.5ci
2	13	0+10ci, 13+2.5ci
3	20 or 13+5ci	13+7.5ci or 20+3ci
4 except Marine	20 or 13+5ci	20+5ci or 13+10ci
5 and Marine 4	20 or 13+5ci	20+5ci or 13+10ci
6	20+5ci or 13+10ci	20+7.5ci or 13+12.5ci
7 and 8	20+5ci or 13+10ci	20+10ci or 13+15ci

Table Notes:

The first R-value is for cavity insulation located between studs; the second value is for continuous insulation (ci) located on the exterior side of studs. Where ‘0’ is indicated, there is no cavity insulation required.
Recommended R-values are based on optimizing: (a) cost effectiveness of energy saving performance over the life of a home for a given climate zone, (b) improved moisture performance (see STEP 3) and (c) reasonable constructability in relation to thermal performance goals for a given climate zone (e.g., see STEP 5 Cladding Connections).

NEXT STEPS: With the energy code compliance design and insulation package specified, proceed to STEP 2.