Attic Insulation in Zone 2 (Hot)
The DOE recommends R-38 for attic insulation in Climate Zone 2 (Hot). This zone has 2,000 heating degree days and 3,500 cooling degree days annually. The typical attic cavity depth is 16 inches. States in Zone 2 include Alabama, Arizona, Florida, Georgia, Louisiana and 2 more.
Quick Facts
Insulation Comparison for Attic in Zone 2
The table below compares all insulation types for achieving R-38 in the attic of a building in Zone 2 (Hot). Types marked "Recommended" are specifically suited for attic applications. Material costs are shown per square foot and per 1,000 square feet for easy budgeting. Labor costs typically add 30 to 100 percent to material costs depending on the insulation type and project complexity.
| Insulation Type | R/Inch | Thickness | $/SqFt | $/1000 SqFt | Fits | Rec. |
|---|---|---|---|---|---|---|
| Blown-In Cellulose | R-3.5 | 10.9" | $2.66 | $2,660 | Yes | Yes |
| Blown-In Fiberglass | R-2.5 | 15.2" | $3.04 | $3,040 | Yes | Yes |
| Vermiculite (Loose Fill) | R-2.1 | 18.1" | $3.80 | $3,800 | No | Yes |
| Fiberglass Batt | R-3.2 | 11.9" | $4.56 | $4,560 | Yes | Yes |
| Expanded Polystyrene (EPS) | R-3.9 | 9.7" | $4.56 | $4,560 | Yes | Yes |
| Mineral Wool Batt | R-3.3 | 11.5" | $5.70 | $5,700 | Yes | Yes |
| Cotton Denim (Recycled) | R-3.5 | 10.9" | $7.60 | $7,600 | Yes | Yes |
| Polyisocyanurate (Polyiso) | R-6 | 6.3" | $8.36 | $8,360 | Yes | Yes |
| Sheep Wool | R-3.5 | 10.9" | $13.30 | $13,300 | Yes | Yes |
| Extruded Polystyrene (XPS) | R-5 | 7.6" | $6.84 | $6,840 | Yes | - |
| Mineral Wool Board | R-4.3 | 8.8" | $9.50 | $9,500 | Yes | - |
| Open-Cell Spray Foam | R-3.7 | 10.3" | $15.20 | $15,200 | Yes | - |
| Closed-Cell Spray Foam | R-6.5 | 5.8" | $30.40 | $30,400 | Yes | - |
| Aerogel Blanket | R-10 | 3.8" | $114.00 | $114,000 | Yes | - |
Installation Guidance
In the warm climate of Zone 2, attic insulation at R-38 serves primarily to reduce cooling costs by blocking solar heat gain through the roof. Combine bulk insulation with a radiant barrier installed on the underside of the roof rafters for maximum cooling season performance. The radiant barrier reflects up to 97 percent of radiant heat from the hot roof deck, reducing the heat load on the insulation below. Ensure proper attic ventilation to exhaust the hot air that accumulates above the insulation. In humid climates within Zone 2, pay careful attention to vapor management — avoid installing a vapor barrier on the warm side of the insulation if the attic is ventilated, as this can trap moisture during occasional cooling periods. Light-colored roofing materials complement the insulation strategy by reducing the temperature of the roof surface itself.
States in Zone 2
The following states include areas within Climate Zone 2. Click any state to see its complete insulation requirements across all applicable zones.