Climate Zone 3 Insulation Guide
Warm climates covering most of the Deep South, Southwest, and inland California. Mixed heating and cooling demands.
R-Value Requirements
Warm to hot summers, moderate winters. Both heating and cooling costs are significant.
Locations in Climate Zone 3
Major cities: Atlanta, Dallas, Las Vegas
States primarily in Zone 3:
Typical Insulation Scenarios
These estimates are for a 1,200 sq ft attic in Climate Zone 3.
| Existing R | Target R | Recommended Material | Estimated Cost |
|---|---|---|---|
| R-0 | R-49 | Blown-in Cellulose | $1,800–$2,600 |
| R-11 | R-49 | Blown-in Cellulose | $1,400–$2,000 |
| R-30 | R-60 | Blown-in Fiberglass | $1,200–$1,800 |
Insulation Depth Required for R-49
| Material | R-Value/Inch | Depth for R-49 |
|---|---|---|
| Blown-in Fiberglass | ~2.5 | ~20" |
| Blown-in Cellulose | ~3.5 | ~14" |
| Blown-in Mineral Wool | ~3.15 | ~16" |
| Open-Cell Spray Foam | ~3.6 | ~14" |
| Closed-Cell Spray Foam | ~6.5 | ~8" |
Frequently Asked Questions
What R-value is required in Climate Zone 3?
The IECC code minimum is R-49. ENERGY STAR recommends R-60. If your existing insulation is below R-49, 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 3 Home
Enter your zip code for a precise material recommendation and cost estimate for your attic.
Get My Free Estimate