Closed-Cell Spray Foam in Zone 2 (Hot)
Closed-Cell Spray Foam provides R-6.5 per inch of thickness at a material cost of $0.80 per square foot per R-value point. In Climate Zone 2 (Hot), with 2,000 HDD and 3,500 CDD, see the thickness and cost required for each building component below.
Specifications
Closed-Cell Spray Foam Requirements by Component in Zone 2
The table below shows the DOE recommended R-value, required thickness of Closed-Cell Spray Foam, material cost per square foot, and total material cost per 1,000 square feet for each building component in Climate Zone 2. Components where Closed-Cell Spray Foam is specifically recommended are highlighted. Components where insulation is not required show "N/R" (not required).
| Component | Required R | Thickness | $/SqFt | $/1000 SqFt | Fits Cavity | Rec. |
|---|---|---|---|---|---|---|
| Attic | R-38 | 5.8" | $30.40 | $30,400 | Yes | - |
| Wall Cavity | R-13 | 2" | $10.40 | $10,400 | Yes | Yes |
| Wall Continuous (Exterior) | N/R | - | - | - | - | - |
| Floor (Over Unconditioned Space) | R-13 | 2" | $10.40 | $10,400 | Yes | - |
| Basement Wall | N/R | - | - | - | - | Yes |
| Crawlspace | N/R | - | - | - | - | Yes |
| Cathedral Ceiling | R-22 | 3.4" | $17.60 | $17,600 | Yes | Yes |
| Garage Ceiling (Below Living Space) | R-19 | 2.9" | $15.20 | $15,200 | Yes | - |
Closed-Cell Spray Foam in Zone 2 — Guidance
Closed-cell spray foam at R-6.5 per inch is particularly valuable in Zone 2 (Hot) for moisture-sensitive applications such as crawlspaces and below-grade walls where its waterproof properties provide critical moisture protection. In humid Zone 2 climates, the vapor barrier properties of closed-cell foam help prevent moisture-laden outdoor air from reaching cool interior surfaces and causing condensation. While the high cost per R-value makes closed-cell foam less economical for large, open areas like attics (where cheaper blown-in products can achieve the same R-value at much lower cost), it excels in applications where moisture control, space constraints, and structural performance justify the premium price.
States in Zone 2
These states include areas within Climate Zone 2 where the Closed-Cell Spray Foam requirements shown above apply. Click any state for its complete insulation recommendations.