_optimized.webp&w=2048&q=72)
Open Cell vs Closed Cell Spray Foam
The complete 2026 guide to choosing the right type of spray foam insulation for your Michigan home. R-value, cost, best uses, and expert recommendations from our SPFA-trained crews.
Understanding Open Cell vs Closed Cell Spray Foam
Choosing between open cell and closed cell spray foam is the most important decision in any Michigan insulation project. Each type has the right job — and using the wrong one can waste thousands of dollars or create moisture problems that take years to surface. This guide walks you through everything our SPFA-trained estimators consider when specifying spray foam for luxury Metro Detroit homes.
Both types of spray foam are made from the same base chemistry: two liquid components (A and B) that react when mixed to form a rigid polyurethane. The difference is the density. Open-cell spray foam expands to roughly 100 times its original volume and cures at about 0.5 pounds per cubic foot — soft, flexible, and filled with tiny air pockets. Closed-cell spray foam expands only 30 times and cures at about 2.0 pounds per cubic foot — rigid, dense, and impermeable to water.
That density difference drives every other property: R-value, vapor permeability, structural strength, sound dampening, and cost. Understanding how each property matches your specific application is the key to a successful project.
Quick Comparison
| Property | Open Cell | Closed Cell |
|---|---|---|
| R-value per inch | 3.5–3.8 | 6.5–7.0 |
| Density | 0.5 lb/ft³ | 2.0 lb/ft³ |
| Vapor barrier | No | Yes |
| Structural strength | Minor | Significant (250% racking) |
| Sound dampening | Excellent | Good |
| Cost per board foot | $0.50–$1.50 | $1.00–$2.50 |
| Water resistance | Absorbs water | Waterproof |
| Best for | Interior walls, attic rafters | Crawl, basement, roof deck, pole barn |
Open Cell Spray Foam — Best Uses
Open cell spray foam is soft, expands to 100 times its original volume, and is filled with tiny air pockets that give it excellent sound dampening properties. It's also significantly cheaper than closed cell per board foot, which makes it the cost-effective choice for large areas where vapor control isn't critical.
- Interior wall cavities (between rooms)
- Attic rafters in vented attic assemblies
- Sound isolation between floors
- Bedroom and media room walls
- Large cavities where cost matters more than R-value per inch
Closed Cell Spray Foam — Best Uses
Closed cell spray foam is rigid, dense, waterproof, and delivers the highest R-value per inch of any insulation on the market. It acts as a vapor barrier in a single application and adds significant structural strength. For Michigan's cold humid climate, closed cell is the only correct choice in any cavity where moisture or frost is a concern.
- Crawl space rim joists and foundation walls
- Basement walls and rim joists
- Conditioned attic roof decks
- Pole barns and metal buildings
- Cathedral ceilings and dormers
- New construction wall systems (structural bonus)
- Any cavity where vapor barrier performance is required
Which Foam for Your Project?
Explore Our Services
Frequently Asked Questions
Reference: Spray Polyurethane Foam Alliance
Begin Your Project
Ready When You Are
Same-day consultations throughout Metro Detroit. A quieter, warmer, tighter home awaits.