Overview
- Determine your Climate Zone (see Figure 1 or Chapter 3 of the IECC-C)
- For a prescriptive R-value recommendation, refer to Table 2 below.
- For the prescriptive U-factor method to determine alternative R-value solutions for compliance, refer to the Wood Frame Wall Calculator.
- For the Total Building Performance method, refer to an energy modeling professional to determine compliance.
Table 2
Wood-frame Wall Ci R-values for Energy Code Compliance1
[Commercial Buildings including Multi-Family > 3 stories]
| CLIMATE ZONE | Minimum R-values (greater of IECC-C Group R and all others) | Recommended R-values2 |
| 1 | 13+3.8ci or 20 | 13+3.8ci or 0+13ci |
| 2 | 13+3.8ci or 20 | 13+3.8ci or 0+13ci |
| 3 | 13+3.8ci or 20 | 20+2.5ci or 13+7.5ci |
| 4 except Marine | 13+3.8ci or 20 | 20+5ci or 13+10ci |
| 5 and Marine 4 | 13+7.5 or 20 + 3.8ci | 20+5ci or 13+10ci |
| 6 | 13+7.5 or 20 + 3.8ci | 20+7.5ci or 13+12.5ci |
| 7 | 13+7.5 or 20 + 3.8ci | 20+10ci or 13+15ci |
| 8 | 13+15.6ci or 20+10ci | 20+10ci or 13+15.6ci |
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 building in 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 4 Cladding Connections). If complying with the enhanced envelope additional energy efficiency package option of IECC-C Section C406, additional wall ci R-value should be considered.
NEXT STEPS: With the energy code compliance design and insulation package specified, proceed to STEP 2.