Closed-Cell Spray Foam in Zone 5 (Cool)
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 5 (Cool), with 6,500 HDD and 800 CDD, see the thickness and cost required for each building component below.
Specifications
Closed-Cell Spray Foam Requirements by Component in Zone 5
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 5. 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-49 | 7.5" | $39.20 | $39,200 | Yes | - |
| Wall Cavity | R-13 | 2" | $10.40 | $10,400 | Yes | Yes |
| Wall Continuous (Exterior) | R-5 | 0.8" | $4.00 | $4,000 | Yes | - |
| Floor (Over Unconditioned Space) | R-25 | 3.8" | $20.00 | $20,000 | Yes | - |
| Basement Wall | R-10 | 1.5" | $8.00 | $8,000 | Yes | Yes |
| Crawlspace | R-10 | 1.5" | $8.00 | $8,000 | Yes | Yes |
| Cathedral Ceiling | R-38 | 5.8" | $30.40 | $30,400 | Yes | Yes |
| Garage Ceiling (Below Living Space) | R-30 | 4.6" | $24.00 | $24,000 | Yes | - |
Closed-Cell Spray Foam in Zone 5 — Guidance
Closed-cell spray foam at R-6.5 per inch is particularly valuable in Zone 5 (Cool) for applications where its dual function as insulation and moisture barrier provides the greatest value. In the mixed climate of Zone 5, both heating and cooling seasons create vapor drives that can move moisture through wall assemblies. Closed-cell foam at 2 inches or more acts as a vapor retarder, helping to manage these bidirectional moisture drives. It is most cost-effective at rim joists, crawlspace walls, basement walls, and cathedral ceilings where its high R-value per inch and moisture resistance provide benefits that cheaper insulation types cannot match.
States in Zone 5
These states include areas within Climate Zone 5 where the Closed-Cell Spray Foam requirements shown above apply. Click any state for its complete insulation recommendations.