The short answer
Open-cell spray foam costs less per board foot: Angi and HomeAdvisor give $0.60 to $1.60 installed, against $1.30 to $3.10 for closed-cell. But closed-cell gives more R-value per inch, so the fair comparison is cost at the same R-value. At range midpoints, reaching about R-20 over 1,000 square feet works out to roughly $5,946 for open-cell and $7,097 for closed-cell, if both are suitable for that part of the house.
For a fair price comparison, work out the installed depth needed for the intended thermal performance, multiply by the treated area, then include job minimums, surface preparation and any required protective finishes. A higher-priced closed-cell product can fit into a thinner cavity; a lower-priced open-cell product can sometimes deliver a cheaper assembly where extra depth is available.
Bottom line: Open-cell usually wins on initial installed price for the same thickness. Closed-cell often needs less thickness for a similar nominal R-value. Neither is automatically cheapest when you compare suitable, finished assemblies.
US pricing reviewed October 19, 2026. Examples below use transparent calculations from published rates, not actual contractor bids. Use our spray foam cost calculator for your own dimensions.
Open-Cell vs Closed-Cell Spray Foam Cost at a Glance
| Price or performance factor | Open-cell spray foam | Closed-cell spray foam |
|---|---|---|
| Angi installed price per board foot | $0.60–$1.60[1][2] | $1.30–$3.10[1][2] |
| Typical nominal R-value per inch | Around R-3.6 to R-4.5[3] | Around R-5.8 to R-6.9[3] |
| Illustrative R-value used in our calculations | R-3.7/in | R-6.2/in |
| Cost at 2 inches, per treated sq ft | $1.20–$3.20 | $2.60–$6.20 |
| Cost at 3.5 inches, per treated sq ft | $2.10–$5.60 | $4.55–$10.85 |
| General price advantage | Lower unit cost | More R-value per inch |
| Moisture behavior | Generally more vapor-permeable | Generally less vapor-permeable |
Prices at 2 and 3.5 inches are mathematically derived from Angi’s installed board-foot bands; they are not independently surveyed thickness-specific quotes. Product R-values vary.
This article focuses on what the two options cost, rather than re-explaining all their technical properties. For the materials comparison, read open-cell vs closed-cell spray foam.
How Much More Expensive Is Closed-Cell Spray Foam?
At the same board-foot quantity, closed-cell costs more under Angi’s published ranges. Using the midpoints of those bands as illustrations:
- Open-cell: $1.10 per board foot.
- Closed-cell: $2.20 per board foot.
- At the same depth and treated area, the midpoint closed-cell unit rate is twice the midpoint open-cell rate.
That does not mean every real-world closed-cell quote is exactly twice an open-cell quote. The rate ranges overlap, job minimums matter, and the products may be specified at different thicknesses.
Another caution: some 2026 pricing guides use narrower rates. Angi’s general insulation-installation article lists open-cell at approximately $0.44–$0.65 per board foot and closed-cell at $1–$1.50[4], with different stated assumptions. Don’t combine pricing from different surveys to manufacture a precise national average.
Practical takeaway: Treat public pricing as a budgeting range. Ask local contractors to quote both products against the same performance brief, not just the same inches of spray foam.
Cost per Square Foot: Why Thickness Changes Everything
Price per square foot = price per board foot × inches, so the same foam costs twice as much at 4 inches as at 2. Comparing the two foams at the same thickness is misleading, because they deliver different R-values; the next sections compare them fairly. The full table by thickness is on the cost per square foot page.
Open-Cell vs Closed-Cell Cost for 1,000 Square Feet
Assume 1,000 square feet of actual surface needs insulation. At three different thicknesses, the price arithmetic looks like this:
| Thickness | Board feet | Open-cell estimate | Closed-cell estimate |
|---|---|---|---|
| 2 in | 2,000 | $1,200–$3,200 | $2,600–$6,200 |
| 3.5 in | 3,500 | $2,100–$5,600 | $4,550–$10,850 |
| 5.5 in | 5,500 | $3,300–$8,800 | $7,150–$17,050 |
Calculated installed foam-volume totals; separately billed work and minimum charges may change the final project cost.
The mistake to avoid: Using the home’s floor area as the spray area. A 1,000-square-foot attic floor is not necessarily the same size as the sloped roof deck, and a 1,000-square-foot house may have substantially more than 1,000 square feet of exterior wall area.
Which Foam Is Cheaper at the Same R-Value?
This is the comparison most pricing articles miss.
Closed-cell foam offers more nominal thermal resistance per inch, so comparing both foams at two inches isn’t a comparison of equivalent insulation performance. The next table targets approximately R-20 of foam material using illustrative values of R-3.7 per inch for open-cell and R-6.2 per inch for closed-cell.
| Equal nominal material target | Open-cell | Closed-cell |
|---|---|---|
| Example R-value per inch | R-3.7 | R-6.2 |
| Thickness for nominal R-20 | 5.41 in | 3.23 in |
| Required board feet for 1,000 sq ft | ~5,405 | ~3,226 |
| Calculated installed foam cost | $3,243–$8,649 | $4,194–$10,001 |
| Midpoint-rate cost illustration | ~$5,946 | ~$7,097 |
Rounded illustration: 20 ÷ 3.7 and 20 ÷ 6.2; volume multiplied by Angi’s reported installed board-foot ranges. The actual quoted price need not scale linearly with thickness.
At those illustrative midpoints, open-cell is roughly $1,151 cheaper across 1,000 treated square feet for the same nominal foam R-value. But it’s not always an available alternative.
In a limited-depth cavity, the 5.41-inch open-cell layer might not fit. In a particular damp or below-grade assembly, open-cell may not be an appropriate design. In other assemblies, the lower drying potential of closed-cell may be undesirable.
Also, equal material R-value is not equal whole-wall performance. Framing, continuous insulation, thermal bridges, air leakage and other layers all influence assembly performance and code compliance.
The lowest price for an appropriate assembly matters. Not the lowest hypothetical price for material you cannot safely or legally install there.
How to Compare Real Contractor Quotes at Equal Performance
Here’s a worked quote-comparison example for 1,000 treated square feet, using hypothetical rates within the broad 2026 bands:
| Component | Open-cell option | Closed-cell option |
|---|---|---|
| Product’s nominal R-value | R-3.7/in | R-6.2/in |
| Target material R-value | R-20 | R-20 |
| Estimated thickness | 5.41 in | 3.23 in |
| Calculated board feet | 5,405 | 3,226 |
| Hypothetical installed rate | $0.90/bf | $1.90/bf |
| Calculated foam charge | $4,865 | $6,129 |
| Additional scope costs | Compare item by item | Compare item by item |
At these rates the open-cell option starts approximately $1,264 cheaper. If the closed-cell design avoids required extra assembly work or solves a depth constraint, that difference might narrow or reverse. If one estimate excludes protective coatings, site prep or demolition, it may not be the cheaper finished project.
Ask each bidder to identify the exact foam product, specified thickness, coverage, R-value, barrier requirements and total price. Only compare products for the same location once the assembly design confirms both are suitable.
Upfront Cost vs Lifetime Value
A more expensive insulation system can make sense when it solves a real building constraint or reduces other necessary construction costs. But you shouldn’t assume closed-cell automatically “pays for itself” faster just because it has a higher R-value per inch.
Energy savings are assembly-dependent. Both materials can reduce air leakage when correctly installed. Once a building is adequately insulated and sealed, increasing foam thickness may deliver diminishing financial returns.
A reliable payback calculation needs your climate, heating and cooling use, existing building conditions, energy rates, actual bids, and the performance of the proposed whole building design. Neither a generic 20-year promise nor a fixed savings percentage is a credible substitute.
For overall budgeting, use the main spray foam insulation cost guide.
Where the Extra Closed-Cell Cost Might Make Sense
Shallow Wall Cavities
When space is limited, closed-cell’s higher R-value per inch can be valuable. A foam-only comparison is insufficient, though: the local energy code may require specific whole-wall or continuous-insulation approaches.
Rim Joists, Crawl Spaces and Below-Grade Details
Closed-cell’s relatively low vapor permeability can be useful in suitable details. But it does not fix bulk-water intrusion or substitute for drainage and water management. Some applications require clear pest-inspection access, ignition protection or other special provisions.
Metal Buildings
Closed-cell is often evaluated for metal-building assemblies where thin insulation and air sealing are valuable. Condensation control requires a full thermal and moisture design rather than simply spraying the cheapest product onto metal.
Attic Roof Decks
Roof-deck insulation requires careful treatment of moisture, ventilation, sheathing drying and code requirements. Both foam types can appear in suitable roof assemblies, but neither should be selected on unit price alone.
Read the attic spray foam guide before accepting a roofline quote.
Where Open-Cell Can Offer Better Value
Accessible Above-Grade Wall Cavities
When the cavity is deep enough and the wall assembly is correctly designed for the climate, open-cell can deliver insulation and air sealing with a lower foam-volume cost.
Interior Sound-Control Projects
Open-cell is sometimes considered for its sound-absorption properties, but acoustical performance depends on the full wall or ceiling assembly. Don’t assume one foam type delivers a particular STC rating without a tested construction.
Larger, Suitable Coverage Areas
For surfaces requiring substantial insulation depth where open-cell is technically suitable, the lower board-foot rate can make the total project cheaper. Compare actual completed-scope bids.
For a full cost breakdown, use the open-cell spray foam cost guide. For the alternative, see closed-cell spray foam cost.
Additional Costs That Can Change the Winner
Minimum job charges, old-insulation removal, surface preparation, required fire or ignition protection, access and warranty terms can matter more than the foam price. Ask for both foams quoted with the same line items. See the main cost guide.
Is Open-Cell or Closed-Cell Better for a Tight Budget?
If both options are appropriate and compliant, open-cell is usually the cheaper system to price first because of its lower unit rate. It is not worth specifying open-cell in a damp, shallow or otherwise unsuitable assembly just to save money.
If neither type can meet the required performance economically, a different insulation approach or hybrid design may be more sensible. “Spray foam” is a product category, not a compulsory answer to every insulation problem.
Questions owners ask
Is open-cell spray foam cheaper than closed-cell?
Generally yes, per board foot. Angi reports $0.60–$1.60 installed for open-cell and $1.30–$3.10 for closed-cell in its pricing guide. The total project difference depends on thickness and additional work.
How much more does closed-cell cost?
At the published range midpoints, closed-cell is twice the price per board foot in a mathematical illustration. Actual contractor differences vary, and equal R-value may call for different thicknesses.
Is closed-cell cheaper at the same R-value?
Not necessarily. It typically needs less depth, but costs more per board foot. In the illustrative R-20 example above, open-cell remains cheaper at the range midpoints, assuming both products are technically appropriate.
How much does it cost to insulate 1,000 square feet?
At two inches thick, calculated installed foam costs are approximately $1,200–$3,200 for open-cell or $2,600–$6,200 for closed-cell using Angi's rates. “1,000 square feet” must mean the actual treated surface.
Which foam is better for attics?
There is no universal winner. Roof-deck assemblies need climate-appropriate moisture and drying design, code-compliant insulation, air sealing and proper protection. Compare suitable systems rather than selecting on price alone.
Does closed-cell pay for itself through energy savings?
Sometimes a premium insulation assembly makes economic sense, but a specific payback cannot be assumed. Climate, air leakage, existing insulation, installed quality and energy prices determine the outcome.
Should I get two separate quotes?
Yes. Where both foam types could be appropriate, request alternative written proposals for the same performance goal with the same included services. That makes the real price difference visible.
Sources
- How Much Does Spray Foam Insulation Cost?, Angi. Accessed October 19, 2026. National consumer cost guide from a survey of Angi customers. No update date shown; title says "2025 Data". Its installed per-board-foot ranges match HomeAdvisor's page updated June 17, 2026.
- How Much Does Spray Foam Insulation Cost?, HomeAdvisor. Accessed October 19, 2026. National consumer cost guide, updated June 17, 2026. Installed cost per board foot; national ranges, not quotes.
- Frequently Asked Questions, Spray Polyurethane Foam Alliance (SPFA). Accessed October 19, 2026. Industry trade association. Page metadata shows modified April 27, 2026. Typical density, R-value per inch, air-barrier thickness and vapor permeance ranges.
- How Much Does Insulation Installation Cost?, Angi. Accessed October 19, 2026. Updated October 6, 2026. Gives lower per-board-foot spray foam figures under different assumptions.