Comparison · read from the product records

Open-Cell vs Closed-Cell Spray Foam Kits: Choose the Assembly Before the Box

Closed cell buys more published R per inch and, in one fully documented record, a vapor-retarder figure. Open cell buys a softer, lower-density fill and is the only side in our tracked set with published sound figures. There is no honest cost-per-R winner because neither open-cell listing pairs a current single-kit price with coverage at a stated thickness.

Research by Best Spray Foam research desk · Published and updated September 20, 2026

The short answer

Which one, and when neither

Open cell, for a dry interior cavity where sound absorption and full-depth fill lead
HandiFoam Low Density is the open-cell record with a sheet: R-4.3 at 1 inch, 0.75 lb/ft3 free-rise density, and STC 35 plus NRC 0.70 in the 3-inch wall assembly the maker describes. Those sound figures belong to that assembly and product, not to every open-cell kit.
Closed cell, where inches are scarce or the exact assembly needs a vapor-control number
HandiFoam FR publishes R-6.4 aged at 1 inch and 0.9 perm at 1 inch, which its sheet calls a Class II vapor retarder. Those are product-specific figures. Check the sheet for the foam and thickness you will actually install rather than transferring them to the closed-cell label as a whole.
Neither kit, until the moisture, fire and occupancy plan is settled
Cell type does not choose the assembly for you. Roof decks, crawl spaces, below-grade walls and framed cavities can put different demands on drying direction, ignition or thermal protection, and local approval. The two documented HandiFoam records also say professional use only, so a DIY checkout button does not overrule the product sheet.

The tracked shelf

Two open-cell records, six closed-cell records

This is the set Best Spray Foam had documented on September 8, 2026. It is a tracked US retail set, not the whole market.

2open-cell systems1 with a published product-specific sheet

6closed-cell systems3 with a published product-specific sheet

Like maker, two cell types

The HandiFoam sheets, without forcing unlike tests into a winner

HandiFoam is the only maker in this tracked set with a published sheet on both sides. Even here, the aged R-values use different aging conditions and the fire rows use different test thicknesses, so the table states both and crowns neither.

Row	Open cell	Closed cell
R-value	R-4.3 at 1 in, aged 90 days at 140 FASTM C518, aged value printed	R-7.0 initial and R-6.4 aged 180 days at 75 F, both at 1 inASTM C518, initial and aged values both printed
Density and cell content	0.75 lb/ft3 free rise, 1.12 in place; closed-cell content 5 percent	1.75 lb/ft3 free rise, 2.10 in place; closed-cell content over 90 percent
Vapor figure	Not published on this sheet	0.9 perm at 1 in, which the sheet itself calls a Class II vapor retarder
Surface burning	ASTM E84 flame spread 50, smoke developed 400, tested at 4 in: Class 2 (B), stated as such	Class A: ASTM E84 flame spread 10, smoke developed 350, tested at 2 in; CAN/ULC-S102 at 4 in beads FSI 15, SDI 75; ICC-ES ESR-2717
Sound figures	STC 35 and NRC 0.70 at 3 inThe sheet describes the test wall; it gives no same-wall result without foam.	No STC or NRC figure on the sheet
Maker’s audience	"For professional use only"	"For professional use only," printed on the sheet

Why the cost answer stops

The open-cell price cannot be divided by R without inventing a thickness

Vega Bond Open Cell Spray Foam Insulation Kit lists 320 or 1,100 sq ft and store offers at $399.99 for 320 sq ft kit and $799.99 for 1,100 sq ft kit. Its page does not state a coverage thickness. HandiFoam Low Density (open cell) II-250, II-450 and II-1350 states 250, 450 and 1,350 board feet, but the Amazon record is a four-pack at $2,102.79 and does not identify one kit size. Neither record supplies one price, one yield and one thickness on the same basis.

Every record behind the comparison

Open the exact product before applying a class rule

Open-cell kits

Vega Bond Open Cell320 or 1,100 sq ftNo product-specific sheet found
HandiFoam Low Density250, 450 and 1,350 board feetProduct-specific sheet published

Closed-cell kits

Froth-Pak 200200 sq ft at 1 inProduct-specific sheet published
Froth-Pak 630630 sq ft at 1 inProduct-specific sheet published
Froth-Pak 12Not stated on the Amazon listing we read; the frothpak.dupont.com products page lists only the 200 and 630No product-specific sheet found
Stanley F994C SuperCoatUp to 200 board feet, or 600, at 1 inNo product-specific sheet found
Vega Bond V200 to V600200, 400 or 600 board feet at 1 inNo product-specific sheet found
HandiFoam FR (HFO)201 and 601 board feetProduct-specific sheet published

Outside the product records

The primary guidance used for the class-level statements

Product rows come from the exact maker records above. These sources support the broader statements about cell structure, product formats, exposure controls and ventilation.

What would change this

The missing piece, named

A current one-kit price for HandiFoam Low Density, tied to one named yield, would create the first defensible open-cell price per stated board foot in this set.
A stated thickness behind Vega Bond Open Cell coverage would make its 320- and 1,100-square-foot prices usable in cost-per-R arithmetic.

Asked about this pair

Questions people type, answered from the records

Is closed-cell spray foam always better than open cell?

No. Closed cell usually puts more R-value into each inch and can add vapor resistance at a product-specific thickness. Open cell is softer, lower density and may suit a dry interior cavity or an assembly designed to dry through the foam. The right answer follows the wall, roof or crawl-space assembly and the exact product sheet.

Which type is better for sound?

Open cell has the only product-specific sound evidence in our tracked kit set. HandiFoam Low Density publishes STC 35 and NRC 0.70 for a described wall with 3 inches of foam. Those are assembly results, not a promise that any open-cell kit will deliver the same number in a different wall.

Can open-cell spray foam be an air barrier?

Yes, at the thickness documented for the exact product. Air control and vapor control are separate jobs: an open-cell foam can limit air movement while remaining vapor permeable. Do not borrow a generic thickness when the product sheet or code report gives its own.

Why is there no cost-per-R winner on this page?

The open-cell records do not provide all three inputs on one current, matching offer: price, coverage and coverage thickness. Vega Bond publishes prices and square-foot coverage without thickness; the HandiFoam Amazon offer is a four-pack without one named kit yield. Filling either gap with an assumption would manufacture a winner.

How this page is built

Nothing here was sprayed by us

This comparison reads what each maker publishes and what the listings show; it is not a hands-on test. Every figure in the tables comes from the product records behind the full record pages, with the document it came from and the date we read it, and it changes on this page the day a record is re-read. A side is marked ahead only when both were measured the same way, or when only one maker put the figure in writing. The rules behind the order on the category pages are in the methodology.

Questions answered from these records

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