Polyisocyanurate (Polyiso) in Zone 3 (Warm)
Polyisocyanurate (Polyiso) provides R-6 per inch of thickness at a material cost of $0.22 per square foot per R-value point. In Climate Zone 3 (Warm), with 3,500 HDD and 2,000 CDD, see the thickness and cost required for each building component below.
Specifications
Polyisocyanurate (Polyiso) Requirements by Component in Zone 3
The table below shows the DOE recommended R-value, required thickness of Polyisocyanurate (Polyiso), material cost per square foot, and total material cost per 1,000 square feet for each building component in Climate Zone 3. Components where Polyisocyanurate (Polyiso) 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 | 6.3" | $8.36 | $8,360 | Yes | Yes |
| Wall Cavity | R-13 | 2.2" | $2.86 | $2,860 | Yes | - |
| Wall Continuous (Exterior) | N/R | - | - | - | - | Yes |
| Floor (Over Unconditioned Space) | R-19 | 3.2" | $4.18 | $4,180 | Yes | - |
| Basement Wall | R-5 | 0.8" | $1.10 | $1,100 | Yes | - |
| Crawlspace | R-5 | 0.8" | $1.10 | $1,100 | Yes | - |
| Cathedral Ceiling | R-30 | 5" | $6.60 | $6,600 | Yes | Yes |
| Garage Ceiling (Below Living Space) | R-19 | 3.2" | $4.18 | $4,180 | Yes | - |
Polyisocyanurate (Polyiso) in Zone 3 — Guidance
Polyisocyanurate (Polyiso) at R-6 per inch provides excellent thermal performance in a thin profile, making it ideal for applications where space is limited. In Climate Zone 3 (Warm), the moderate R-value requirements provide flexibility in choosing between different insulation types based on your specific application and budget. This product is suitable for DIY installation, which can reduce total project costs by 30 to 50 percent compared to professional installation. Ensure that Polyisocyanurate (Polyiso) is installed in a dry location protected from direct moisture exposure. For the specific R-value requirements in Zone 3, review the component comparison table above to see the thickness and cost for each building component.
States in Zone 3
These states include areas within Climate Zone 3 where the Polyisocyanurate (Polyiso) requirements shown above apply. Click any state for its complete insulation recommendations.