Open-Cell Spray Foam Insulation
Open-cell spray polyurethane foam (ocSPF) is a two-component system that is mixed and sprayed on-site, expanding to fill cavities completely. It provides excellent air sealing by conforming to every surface irregularity and penetration in the framing. Open-cell foam is vapor permeable, allowing moisture to pass through rather than trapping it, which can be an advantage in certain wall assemblies. It is softer and more flexible than closed-cell foam, and it has a lower R-value per inch. Open-cell foam requires professional installation by certified spray foam contractors and must be covered with an approved thermal barrier (typically half-inch drywall) when installed in occupied spaces due to fire code requirements.
Open-Cell Spray Foam Specifications
Best Applications for Open-Cell Spray Foam
Open-Cell Spray Foam is recommended for the following building components. Each application link shows the specific R-value requirements by climate zone and how Open-Cell Spray Foam compares against other insulation options for that component.
Thickness Required by Climate Zone
The table below shows the thickness of Open-Cell Spray Foam needed to achieve the DOE recommended R-value for each building component in every climate zone. Cells showing "N/R" indicate that insulation is not required for that component in that zone. Use this table to quickly determine how much Open-Cell Spray Foam you need for your specific zone and application.
| Zone | Attic | Wall Cavity | Wall Cont. | Floor | Basement | Crawlspace | Cathedral | Garage |
|---|---|---|---|---|---|---|---|---|
| Zone 1 | 8.1" | 3.5" | N/R | 3.5" | N/R | N/R | 5.9" | 5.1" |
| Zone 2 | 10.3" | 3.5" | N/R | 3.5" | N/R | N/R | 5.9" | 5.1" |
| Zone 3 | 10.3" | 3.5" | N/R | 5.1" | 1.4" | 1.4" | 8.1" | 5.1" |
| Zone 4 | 13.2" | 3.5" | 1.4" | 6.8" | 2.7" | 2.7" | 10.3" | 8.1" |
| Zone 5 | 13.2" | 3.5" | 1.4" | 6.8" | 2.7" | 2.7" | 10.3" | 8.1" |
| Zone 6 | 16.2" | 3.5" | 2.7" | 6.8" | 4.1" | 2.7" | 13.2" | 10.3" |
| Zone 7 | 16.2" | 3.5" | 2.7" | 6.8" | 4.1" | 2.7" | 13.2" | 10.3" |
| Zone 8 | 16.2" | 3.5" | 4.1" | 6.8" | 5.1" | 2.7" | 13.2" | 10.3" |
Cost Estimates by Climate Zone (per 1,000 sq ft)
Material cost estimates for Open-Cell Spray Foam at the DOE recommended R-value for each climate zone and component. These are material costs only and do not include labor. Professional installation typically adds 50-100% to the material cost shown below.
| Zone | Attic | Wall Cavity | Wall Cont. | Floor | Basement |
|---|---|---|---|---|---|
| Zone 1 | $12,000 | $5,200 | N/R | $5,200 | N/R |
| Zone 2 | $15,200 | $5,200 | N/R | $5,200 | N/R |
| Zone 3 | $15,200 | $5,200 | N/R | $7,600 | $2,000 |
| Zone 4 | $19,600 | $5,200 | $2,000 | $10,000 | $4,000 |
| Zone 5 | $19,600 | $5,200 | $2,000 | $10,000 | $4,000 |
| Zone 6 | $24,000 | $5,200 | $4,000 | $10,000 | $6,000 |
| Zone 7 | $24,000 | $5,200 | $4,000 | $10,000 | $6,000 |
| Zone 8 | $24,000 | $5,200 | $6,000 | $10,000 | $7,600 |
Advantages and Limitations
Every insulation type has trade-offs that affect its suitability for different applications. Understanding these trade-offs helps you select the right insulation for your specific project requirements, budget, and installation constraints.
Advantages of Open-Cell Spray Foam
- Well-suited for: Wall Cavity, Cathedral Ceiling, Crawlspace
Limitations of Open-Cell Spray Foam
- Higher cost per R-value compared to conventional insulation types
- Requires professional installation — not suitable for DIY
- Poor moisture resistance — not suitable for wet or below-grade locations
Compare Other Insulation Types
Browse specifications and cost analysis for other insulation materials to find the best option for your project.