Open-Cell vs Closed-Cell Spray Foam Cost
Closed-cell costs roughly double open-cell per board foot — here’s the real 2026 Arkansas pricing side by side, and why the cheaper foam isn’t always the cheaper job.
The short answer
Open-cell vs closed-cell spray foam cost: nationally, open-cell averages about $0.60–$1.60 per board foot installed and closed-cell about $1.30–$3.10 (HomeAdvisor). Per square foot, HomeGuide lists open-cell at $1.50–$3.50 and closed-cell at $3.00–$5.00 installed (HomeGuide). Open-cell usually needs more inches for the same R-value. But the two aren’t interchangeable: closed-cell needs about half the thickness to hit the same R-value, blocks moisture, and adds structural rigidity, so the “cheaper” foam per board foot isn’t automatically the cheaper job once you factor in what each space actually needs.
That’s the summary. Below is the full side-by-side cost breakdown by project type, why the price gap exists, and how to tell which foam your space actually needs before you pay for the wrong one.
Open-Cell vs Closed-Cell Spray Foam Cost Per Board Foot
A board foot is one square foot of coverage at one inch of thickness — the unit foam is actually priced by, whether a quote states it that way or not.
| Open-cell | Closed-cell | |
|---|---|---|
| Density | ~0.5 lb/ft³ | ~2 lb/ft³ |
| R-value per inch | ~R-3.7 | ~R-6–R-7 |
| Installed cost per board foot | $0.60–$1.60 | $1.30–$3.10 |
| Thickness for R-19 | ~5 in | ~3 in |
| Vapor retarder | No | Yes, at sufficient thickness |
Closed-cell’s higher R-value per inch closes some of that gap in practice — it needs less thickness to hit the same target — but it rarely closes it completely. See our full board foot vs. square foot breakdown for how contractors quote this differently.
Cost by project type: what each foam actually costs installed
These are real installed ranges for typical Arkansas jobs. Some spaces only make sense with one foam — the column shows the price if that foam were used, even in a job we’d only ever spray with the other.
| Pricing measure | Open-cell | Closed-cell |
|---|---|---|
| Installed cost per square foot | $1.50–$3.50 | $3.00–$5.00 |
| Commonly used for | Interior walls, attics in moderate climates, sound reduction | Exterior walls, basements, crawl spaces, moisture-prone areas |
Notice the “not recommended” rows — that’s not a sales pitch, it’s the honest tradeoff. Open-cell absorbs moisture instead of blocking it, which rules it out below-grade or against bare metal at any price. See the full 2026 pricing guide for cost by every project type, mixed or single-foam.
Why closed-cell costs roughly double
The price gap isn’t markup — it’s chemistry and density. Closed-cell cures at about 2 lb per cubic foot, roughly four times the density of open-cell’s 0.5 lb, using more raw material per board foot sprayed. That denser cell structure is also what gives closed-cell its higher R-value per inch, its rigidity, and its ability to block vapor — three things ½-lb open-cell simply doesn’t do.
You’re not paying double for the same thing sprayed differently — you’re paying for a different material with different properties. That’s why “just use the cheaper one everywhere” is the wrong question; the right question is which properties the space actually needs.
Which one your space actually needs
Choose open-cell when
If open-cell looks like the right fit, our open cell spray foam insulation in Arkansas page explains where it works best in Arkansas homes, when to avoid it, and what the installation process looks like. It also covers how to prepare your attic before the crew arrives.
Choose closed-cell when
Most whole-building jobs actually blend both
A barndominium or whole-house job rarely uses one foam throughout. Closed-cell goes down low — crawl space walls, rim joists, against any bare metal — where moisture and condensation are the enemy. Open-cell goes up in the roofline and interior walls, where depth, quiet, and cost work in its favor. A blended job is priced by where each foam actually goes, so get a free written estimate for your layout.
See the open-cell insulation guide and closed-cell insulation guide for the full properties breakdown behind each material.
What moves your number either way
Whichever foam your space needs, the same variables push the price up or down: square footage, target thickness, access difficulty, and whether old insulation has to come out first. Removal alone adds about $1.00–$2.50 per square foot nationally to either foam type (HomeGuide). Get the finished thickness in inches, in writing — a bid spraying thinner than your job needs will look cheaper on paper for both open-cell and closed-cell alike.
Common cost questions
Want a number that accounts for both foams in your actual space? Estimates are free.
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Free estimates across Arkansas, with a written quote that spells out which foam goes where and why — not just whichever one is cheaper to sell.