Climate Zone 4 Insulation Guide
Mixed-humid climate covering the mid-Atlantic, parts of the Midwest and Pacific Northwest interior. Balanced heating and cooling seasons.
R-Value Requirements
Hot humid summers and cold winters with significant heating costs. One of the most common US climate zones.
Locations in Climate Zone 4
Major cities: NYC, Philadelphia, DC
States primarily in Zone 4:
Typical Insulation Scenarios
These estimates are for a 1,200 sq ft attic in Climate Zone 4.
| Existing R | Target R | Recommended Material | Estimated Cost |
|---|---|---|---|
| R-0 | R-60 | Blown-in Cellulose | $2,200–$3,200 |
| R-19 | R-60 | Blown-in Cellulose | $1,600–$2,400 |
| R-38 | R-60 | Blown-in Fiberglass | $900–$1,400 |
Insulation Depth Required for R-60
| Material | R-Value/Inch | Depth for R-60 |
|---|---|---|
| Blown-in Fiberglass | ~2.5 | ~24" |
| Blown-in Cellulose | ~3.5 | ~18" |
| Blown-in Mineral Wool | ~3.15 | ~20" |
| Open-Cell Spray Foam | ~3.6 | ~17" |
| Closed-Cell Spray Foam | ~6.5 | ~10" |
Frequently Asked Questions
What R-value is required in Climate Zone 4?
The IECC code minimum is R-60. ENERGY STAR recommends R-60. If your existing insulation is below R-60, upgrading will typically pay back within 5–10 years.
Can I add insulation on top of existing insulation?
Yes — in most cases you can add blown-in insulation directly on top of existing batts or blown-in material. No need to remove old insulation unless it is damaged or contaminated. Air sealing any gaps first maximizes the benefit.
How do I know what climate zone I am in?
Enter your zip code in our calculator and it will automatically determine your climate zone and recommend the correct R-value target for your location.
Calculate for Your Zone 4 Home
Enter your zip code for a precise material recommendation and cost estimate for your attic.
Get My Free Estimate