Open Cell vs Closed Cell Spray Foam: Which is Right for You?

One of the most common questions we get at SprayFoamCalc is: "Should I use open cell or closed cell foam?"

The answer depends on your specific project, budget, and climate. In this guide, we'll compare the two types of spray foam insulation to help you make an informed decision.

What is Open Cell Spray Foam?

Open cell spray foam is a lighter, less dense foam where the tiny cells are not completely closed. This makes the foam softer and more flexible.

• R-Value: Approximately R-3.5 to R-3.8 per inch.
• Best For: Interior walls, soundproofing, and attics in moderate climates.
• Cost: Generally cheaper than closed cell.

Pros:

• Excellent sound dampening qualities.
• Expands significantly (up to 100x), filling nooks and crannies easily.
• Lower cost per board foot.

Cons:

• Lower R-value per inch.
• Not a vapor barrier (requires a separate vapor retarder in some climates).
• Can absorb moisture if not protected.

What is Closed Cell Spray Foam?

Closed cell spray foam is much denser and rigid. The cells are completely closed and packed together, preventing air and moisture from passing through.

• R-Value: Approximately R-6.0 to R-7.0 per inch.
• Best For: Exterior walls, metal buildings, pole barns, basements, and areas prone to moisture.
• Cost: More expensive, but offers higher performance.

Pros:

• Highest R-value per inch of any insulation.
• Acts as a vapor barrier and moisture barrier.
• Adds structural strength to walls and roofs (racking strength).
• Impermeable to water.

Cons:

• Higher cost per board foot.
• Lower expansion rate (requires more material to fill large voids).

Comparison Chart

| Feature | Open Cell | Closed Cell | | :--- | :--- | :--- | | Density | 0.5 lb/cu ft | 2.0 lb/cu ft | | R-Value/Inch | R-3.5 - R-3.8 | R-6.0 - R-7.0 | | Vapor Barrier | No | Yes | | Structural Strength | Low | High | | Water Resistance | Low | High | | Cost | $$ | $$$ |

Which Should You Choose?

Choose Open Cell If:

• You are insulating interior walls for soundproofing.
• You are on a tighter budget and have plenty of space for thicker insulation (to achieve desired R-value).
• You are insulating a roof deck in a dry climate.

Choose Closed Cell If:

• You are insulating a Pole Barn or Metal Building (prevents condensation/sweating).
• You have limited space (e.g., 2x4 walls) and need maximum R-value.
• You are insulating a basement or crawl space where moisture is a concern.
• You want to add structural rigidity to your building.

Calculate Your Cost

Still not sure? Use our

to compare the cost of Open Cell vs Closed Cell for your specific project dimensions. You can toggle between the two types to see the price difference instantly!