Research set · Documents published · Best Spray Foam research desk · Documents checked 2026-09-08
DAP Wall & Cavity Foam, 20 oz wide-spray can Review
DAP Wall & Cavity Foam is a 20 oz one-component can with a wide-spray applicator, a data sheet that names ASTM methods for every figure, an aged R-4.1 at 1 in to ASTM C518, and an E84 result of 10/450 at 2.75 in. It is rated 3.1 from 418 on Amazon and 4.6 from 42 on Walmart. It appears on the wide-spray page as one of three, and here because its maker names wall cavities, rim joists, crawlspaces, attics and basements as its jobs.
Before you decide
DAP Wall & Cavity Foam, 20 oz wide-spray can
- Pack this page compares
- Single can, 1 x 20 oz
- Claimed coverage
- Up to 11 board feet per can (theoretical)
- R-value as published
- R-4.1 / in, aged, ASTM C518
- Evidence
- Documents published
Research summary, not a hands-on test. Product claims on this page are attributed to the sources and dates shown. Before use, read the exact product label, the current safety data sheet and the application instructions, and confirm ventilation, protective equipment, occupant isolation and re-entry or reoccupancy conditions. A surface-burning classification alone does not establish approval to leave foam exposed or to use it in a particular assembly. Included protective items may not meet every requirement for your job; select ventilation and protective equipment from the exact product instructions and the exposure conditions, not from what the box contains.
Report a product error Score Maker’s description Documents Packs and prices Right of reply
Research desk note · editorial opinion, not a test result
What to check first
This is the only product in our tracked set that states its R-value the way the FTC rule asks: ASTM C518, aged, at a thickness, 4.1 at 1 in. The four leading kits print 5.66 per inch from a German conductivity method with no aging basis. Those are different products on different test and aging bases, so the difference of roughly 28 percent between the numbers cannot isolate aging. What DAP shows is what an aged, method-named figure looks like; the others do not print one.
The same can is rated 3.1 from 418 on Amazon and 4.6 from 42 on Walmart. That is the widest gap between two stores for any product we track. Thirty-six percent of the Amazon ratings are one star, the highest share in the set; we have not yet read the pattern behind them, and the obvious first question is whether buyers expected a wide-pattern can to behave like an insulation kit, which the sheet does not claim.
It sits on this page and on the wide-spray page because DAP sells it for both jobs: stud wall cavities, rim joists, crawlspaces, attics and basements, with a wide-angle applicator. It is interior use only and its E84 smoke index at 2.75 in is 450, the Class A ceiling, which the sheet prints.
Best Spray Foam research desk ·
How the manufacturer describes it
Compiled from the DAP technical data sheet and product page and the Amazon and Walmart listings as they read on September 8, 2026. It is the maker’s description, not ours.
- A one-component polyurethane foam in a 20 oz aerosol with a patent-pending wide-spray applicator and an adjustable nozzle for horizontal and vertical patterns, for stud wall cavities, rim joists, crawlspaces, attics and basements.
- ASTM C518 aged R-value 4.1 at 1 in; closed-cell content over 80 percent (ASTM D6226); core density 1.4 pcf (ASTM D1622); expands up to 3x (ASTM C1643).
- ASTM E84 flame spread 10 and smoke developed 450 at 2.75 in; UL classified foamed plastic; "Class A Fire Rated to meet building codes" on the listing.
- Application at 40 to 120 F; tack-free in 7 to 12 minutes; full cure in 4 hours on the listing and 24 hours on the sheet; interior use only.
- Up to 11 board feet per can, stated as a theoretical yield.
Compiled from DAP Wall & Cavity Aerosol Foam technical data sheet and the brand's marketplace listing, read on .
As an Amazon Associate I earn from qualifying purchases. That fee never sets the order or the score.
Documents on file
What exists for this product, what each document says in its own terms, and what it leaves open. A document we have seen but the seller does not publish is described, not hosted.
- Technical data sheet Published by the seller
DAP Wall & Cavity Aerosol Foam technical data sheet · read 2026-09-08
- ASTM C518 aged R-value 4.1 at 1 in; ASTM E84 flame spread 10 and smoke developed 450 at 2.75 in; UL classified foamed plastic
- Core density 1.4 pcf (ASTM D1622); closed-cell content over 80 percent (ASTM D6226); expands up to 3x (ASTM C1643)
- Air permeance under 0.004 CFM/ft2 at 1 in (ASTM E2178); water vapor transmission 4.1 perm at 1 in (ASTM E96)
- Application 40 to 120 F; tack-free 7 to 12 minutes; typically cured in 24 hours; up to 11 board feet per can, theoretical; interior use only
Open:- The sheet carries no revision date.
- The Amazon listing states a full cure in 4 hours against the sheet’s 24 hours.
- The smoke-developed index of 450 is the Class A maximum; the result covers 2.75 in and no thicker application.
- Safety data sheet Published by the seller
DAP Wall & Cavity Foam safety data sheet, English · read 2026-09-08
- Linked from the DAP product page in English and Spanish
- Fire test report Not published on any channel we read
Fire test report · read 2026-09-08
Open:- The sheet prints the indices and the thickness; the laboratory and report number are not published.
The FastCoat, SprayCoat, ThermCoat and SuperCoat documents state the same yield basis of 20 board feet at 1 inch, the same nozzle A for walls and nozzle B for ceilings, the same 1-inch layer advice with water misting between coats, and the same 24-hour cure with a 40-minute cutting time. The SprayCoat and ThermCoat data sheets also carry the same packaging line, 28.7 oz at a gross 2.05 lb with 12 to a box. We record that pattern and draw no conclusion from it: none of the four states a relationship with the others, and we have not established who manufactures any of them.
The one can with an aged, method-named R-value, and the widest rating gap between two stores
| Field | DAP data sheet and page | Amazon listing | Walmart listing |
|---|---|---|---|
| Pack on this page | Single 20 oz can, case of 6 | Single 20 oz at $21.75; pack of 6 listed | Single 20 oz at $21.75; 4-pack and 16-pack listed |
| Net contents per can | 20 oz | 20 oz | 20 fl oz |
| Stated coverage | Up to 11 board feet, theoretical | Not stated | Not stated |
| Stated R-value | ASTM C518 aged 4.1 at 1 in | "Meets ASTM C518 Aged R-Value of 4.1 at 1 in" | Not in the specification table |
| Fire statement | ASTM E84 10/450 at 2.75 in; UL classified | Class A fire rated | Class A in the description |
| Full cure | Typically 24 hours on the sheet | 4 hours | 24 h dry time |
| Sold by | dap.com | DAP Products Inc. | Walmart.com |
| Rating | None shown | 3.1 from 418 | 4.6 from 42 |
What the differences mean
A 1.5-star gap between two stores
Amazon 3.1 from 418 ratings with 36 percent at one star; Walmart 4.6 from 42.
Why it matters. Two audiences reading one can very differently is a pattern to read, not a verdict. It is the largest cross-store gap in our set.
Sources: Amazon listing B0D9J13PTV · Walmart listing 10338854489
Four hours or twenty-four
The Amazon bullet says fully cures in 4 hours; the data sheet says typically cured in 24 hours depending on thickness, temperature and humidity.
Why it matters. Cure time decides when the next pass, the trim and the cover go on; the sheet is the number to plan by.
Sources: DAP Wall & Cavity Aerosol Foam technical data sheet · Amazon listing B0D9J13PTV
Class A at the ceiling
The sheet prints a smoke-developed index of 450 at 2.75 in, which is the maximum the Class A definition allows.
Why it matters. The claim holds, and it holds with no margin. A thicker application than the tested 2.75 in is outside the result.
Sources: DAP Wall & Cavity Aerosol Foam technical data sheet
In the box
- 1 can, 20 oz
- Wide-spray applicator with adjustable nozzle, included
- No gun, cleaner or protective equipment
There is no kit. The applicator is the product’s reason to exist, and it can be cleaned with acetone and reused per the sheet.
Listing signals
- Amazon rating: 3.1 from 418 ratings Platform-reported on September 8, 2026
- Amazon rating spread: 42% five star, 11% four, 4% three, 7% two, 36% one Platform-reported distribution
- Amazon category rank: #44 in Hardware Sealers Platform-reported best sellers rank
- Walmart rating: 4.6 from 42, sold by Walmart.com Platform-reported
The one-star share is the highest in the set and the Walmart rating is among the highest. Platform figures, not a sample we drew. How we weigh ratings and demos: reviews, ads and expansion demos. How we read a fire claim: ASTM E84 and Class A. How coverage units work: coverage and yield.
Each source read on the date shown: DAP Wall & Cavity Aerosol Foam technical data sheet, read 2026-09-08 · Amazon listing B0D9J13PTV, read 2026-09-08 · Walmart listing 10338854489, read 2026-09-08. Prices sit in the pack table below, each with the date it was read.
As an Amazon Associate I earn from qualifying purchases. That fee never sets the order or the score.
Pack sizes
Choose a pack only after matching the exact product, required volume and included equipment. Larger boxes do not automatically cost less per usable board foot. Check pack identity and bundle contents.
Sold by DAP itself on Amazon and by Walmart.com on Walmart at the same $21.75 on September 8, 2026; Walmart also lists 4-packs and 16-packs.
As an Amazon Associate I earn from qualifying purchases. That fee never sets the order or the score. Official stores pay us nothing, and which seller we point to does not change because of the fee.
Product overview
DAP describes a one-component polyurethane foam in a 20 oz aerosol with a patent-pending wide-spray applicator, for stud wall cavities, rim joists, crawlspaces, attics and basements, interior use only, with an aged R-value of 4.1 at 1 in to ASTM C518 and Class A surface-burning results at 2.75 in.
Manufacturer-stated features
- Aged R-4.1 at 1 in - ASTM C518, on the data sheet
- ASTM E84 flame spread 10, smoke developed 450 at 2.75 in
- Closed-cell content over 80 percent (ASTM D6226); core density 1.4 pcf (ASTM D1622)
- Up to 11 board feet per can - theoretical; expands up to 3x
- Application 40 to 120 F; tack-free 7 to 12 minutes; interior use only
Overview synthesized from the brand’s official page and the Amazon listing. Specifications are manufacturer claims, not independently verified.
Eleven board feet a can, theoretical. A single rim joist bay between 2x12 joists at 16 in on center is about 14.5 by 11.25 in, 1.1 sq ft, so at 2 in a can covers roughly five bays on the stated figure; a 150 ft perimeter at 2 in is about 26 cans. It is a touch-up and small-area product by its own sheet.
What stands out
- Aged R-value to ASTM C518, both E84 indices at a stated thickness, density and closed-cell content on the sheet
- Sold by DAP on Amazon and by Walmart.com on Walmart
Open questions
- 3.1 from 418 on Amazon with a 36 percent one-star share
- Cure time differs between the listing and the sheet
Best for
Rim joists, touch-ups and small areas without a gun, with the only aged R-value in the set behind it.
Not for
Whole walls or attics; eleven board feet a can is not a kit, and the maker says interior use only.
All pack sizes & where to buy
| Pack | Claimed coverage | Amazon | Official |
|---|---|---|---|
| Single canMost chosenCompared | 11 bd ft (1 x 20 oz) | Check price | Store |
| 6-Pack | 66 bd ft (6 x 20 oz) | Check price | Store |
Amazon links are per-size. Official links open the brand store, where you pick the size. Prices and availability change - always confirm on the retailer.
As an Amazon Associate I earn from qualifying purchases. That fee never sets the order or the score.
Questions and answers
Questions about DAP Wall & Cavity Foam, 20 oz wide-spray can
Answered from this product’s documents and listings, the same records the rest of this page is built from.
DAP has a right of reply
Everything on this page is a dated reading of documents that can change. If you make or sell this product, or you have read something here that is wrong, send the document. Every submission is read against the record; where it changes the record, the change is dated on the page, and where it does not, the reply says why. A submission cannot buy a position or remove a finding the documents still support, and what moves a record is written down.
Write to the research desk or copy research@beestsprayfoam.com