Indiana climate zone and R-values
Snapshot: ENERGY STAR groups climate zone 5, including Indianapolis, with recommended retrofit attic levels of R-60 if uninsulated and R-49 if 3 to 4 inches already exist. Homeward Insulation separately suggests a typical attic target of R-38 to R-49.
What climate zone applies to Indianapolis?
ENERGY STAR publishes recommended insulation levels for retrofitting existing wood-framed buildings, grouped by climate zone.[1] Public International Energy Conservation Code maps place Indianapolis in climate zone 5, commonly labeled 5A when moisture regimes are shown. This wiki does not assign a zone to every surrounding town; readers should confirm a parcel against a current official map if a program or rebate depends on it.[1][2]
What does the ENERGY STAR retrofit table say for zone 5?
| Location | If the attic is uninsulated | If the attic already has 3–4 inches | Floor |
|---|---|---|---|
| Zones 6, 5 and 4C (ENERGY STAR table) | R-60 | R-49 | R-30 |
Those figures come from the ENERGY STAR recommended R-value table retrieved for this edition, in which zone 5 is grouped with zones 6 and 4C.[1] They are recommendations for existing wood-framed buildings, not a building-permit requirement copied from a local ordinance, and not a measurement of any one Indianapolis attic.
How does that compare with the company tip?
Homeward Insulation’s blown-in page says most Indianapolis-area homes benefit from an attic R-value in the R-38 to R-49 range.[3] R-38 is below the ENERGY STAR uninsulated-attic recommendation of R-60 for zone 5, and R-49 matches the ENERGY STAR step when 3 to 4 inches already exist.[1] This wiki reports both and does not collapse them. A site audit can still recommend a different target because of existing depth, ventilation, air sealing and roof design.[3]
Methodology: the table restates the official ENERGY STAR cells for the zone group that includes zone 5. It does not invent wall-cavity numbers beyond pointing readers to the same ENERGY STAR page, which also discusses walls when siding is removed.[1] Company blog discussions of R-value are attributed as blogs, not as the ENERGY STAR table.[4]
Asked questions
What attic R-value does ENERGY STAR list for zone 5?
R-60 if the attic is uninsulated, and R-49 if 3 to 4 inches already exist, in the retrofit table retrieved 9 November 2026.
Is the company R-38 to R-49 tip the same thing?
No. It is a company suggestion. This wiki keeps it next to the ENERGY STAR table so readers can see the difference.
Continue reading
- Blown-in insulation
- How home insulation works
- Federal energy tax credits
- Service area
- Hiring an insulation contractor
Citations
- ^ a b c d e Recommended Home Insulation R-Values. ENERGY STAR. Retrieved 9 November 2026.
- ^ International Energy Conservation Code climate zones (IECC). International Code Council / ENERGY STAR zone table. Retrieved 9 November 2026.
- ^ a b Blown-In Insulation. Homeward Insulation (homewardinsulation.com). Retrieved 9 November 2026.
- ^ Indiana Homeowners Guide to Optimal R-Value (company blog). Homeward Insulation (homewardinsulation.com). Retrieved 9 November 2026.