Best Spray Foam Between Floor Joists for Sealing and Insulation
The best spray foam between floor joists depends on the size of the project, the gap dimensions, and whether you need thermal insulation, air sealing, or sound control. For broad coverage, consider a two-part kit such as BEEST FullStop or STANLEY Supercoat; for targeted gaps, a single-can product may be easier to handle. DAP specifically lists rim joists and crawlspaces among its uses, while Vega Bond is an open-cell option marketed for between-floor applications.
| Product | Best suited for | Type |
|---|---|---|
| BEEST FullStop | DIY projects needing a complete kit | Spray foam kit |
| STANLEY Supercoat | Larger coverage needs | Closed-cell kit |
| Loctite Tite Foam | Filling gaps up to 3 inches | Aerosol can |
| DAP Wall and Cavity Foam | Rim joists and cavities | Wide-spray aerosol |
| Vega Bond Open Cell | Between-floor sound and thermal insulation | Open-cell kit |
BEEST FullStop Spray Foam Insulation Kit
Best for: DIYers insulating several joist bays or sealing multiple areas who want the applicator and safety items in one kit. The package includes 12 foam cans, a gun, cleaner, gloves, goggles, and a coverall, according to the product listing.
BEEST states that the foam provides an R-value of 8.24 at two inches and has controlled expansion for gap filling. Its listed ASTM E84 results are a Flame Spread Index of 0 and Smoke Developed Index of 120. These details make it a useful option when the project calls for a kit and the stated performance fits the job.
Limitation: The listed capacity is up to 240 board feet, so estimate the area and application thickness before choosing it. Fire performance claims do not replace required building-code assemblies or coverings.
STANLEY F 990P Supercoat Kit
Best for: Projects where the stated coverage of up to 360 square feet is a priority. The listing describes a closed-cell spray foam kit with 18 cans and includes a gun, cleaner, and safety items. It gives an R-value of 11.32 at two inches.
Choose this if you need a larger listed coverage figure than the BEEST kit and want a closed-cell product. The supplied applicator and cleaner are relevant for a multi-bay job, where consistent application and equipment cleanup matter.
Limitation: The available product details do not specify application instructions or joist-bay dimensions. Confirm the required foam thickness, coverage conditions, and safety directions from the product packaging before starting.
Loctite Tite Foam Big Gaps
Best for: Small, targeted sealing jobs rather than insulating an entire floor assembly. Loctite says this polyurethane foam fills, seals, and insulates gaps and cracks up to three inches. Its high-density, uniform-cell structure is intended to provide durable insulation, and the foam is described as flexible enough to tolerate building movement.
Choose this if you have isolated openings or cracks between joists and prefer a single aerosol can over a larger kit. Flexibility can help maintain a seal as building materials move.
Limitation: The listing does not provide a coverage figure or an R-value. For multiple full joist bays, compare a kit with stated coverage instead of assuming one can will cover the area.
DAP Wall And Cavity Foam
Best for: Buyers who want a product listing that specifically names rim joists, crawlspaces, attics, and basements. Its wide-spray applicator is intended for filling, air sealing, and insulating cavities. The listing describes a closed-cell formula and says it can be used on materials including wood, masonry, metal, and drywall.
DAP states that the foam dries tack-free in seven to 12 minutes and fully cures in four hours, depending on thickness, temperature, and humidity. It is also described as Class A fire rated. Check the product instructions and local code requirements for the intended assembly.
Limitation: This is a 20-ounce aerosol product, not a bulk two-part kit. It may be better suited to smaller areas than a project requiring extensive coverage.
Vega Bond Open Cell Spray Foam Kit
Best for: Buyers prioritizing sound absorption as well as thermal insulation between floors. Vega Bond describes this two-component, open-cell foam for between-floor, rim-joist, roof, and ceiling applications. The listing gives an R-value of 8.8 at two inches and identifies the formula as 1 pound per cubic foot.
The kit includes a hose and gun and is marketed for large-area use. Its open-cell format and stated sound-insulation purpose make it distinct from the closed-cell DAP and STANLEY options.
Limitation: Open-cell and closed-cell foams have different properties. Confirm that the product’s moisture behavior and application requirements suit the location before using it in a floor assembly.
Buying Guide: Choosing Spray Foam Between Floor Joists
Do you need a kit or a single can?
For several bays, compare kits by listed coverage, included equipment, and stated R-value at a specified thickness. For a few small cracks, an aerosol can may be simpler. Coverage depends on application thickness and conditions, so use the package directions rather than treating a stated maximum as guaranteed area.
Should you choose open-cell or closed-cell foam?
These products are not interchangeable in every assembly. Vega Bond is open-cell and highlights sound insulation; DAP and STANLEY are described as closed-cell. Compare the product’s instructions, moisture characteristics, and intended use with the location’s needs. Do not select solely by R-value.
What should you check before spraying?
- Measure the joist bays and identify gaps, wires, pipes, or other obstructions.
- Read the label for temperature, ventilation, protective equipment, curing, and cleanup directions.
- Check local building requirements, especially any requirements for foam coverings or fire protection.
- Keep foam away from areas where the product instructions prohibit application, and do not assume a fire-rating statement makes an entire floor assembly code compliant.
Frequently Asked Questions
Can spray foam be used between floor joists?
Some products are marketed for between-floor, cavity, or rim-joist applications. Confirm that the specific product label covers your location and follow its installation instructions.
Which option is best for sound control?
Vega Bond specifically describes its open-cell foam as providing sound insulation. Its listing gives an R-value of 8.8 at two inches; check whether its other properties fit the assembly.
Is spray foam enough to meet building code?
Not necessarily. Product fire claims do not by themselves establish that a complete floor assembly complies with local code. Check applicable requirements for foam, coverings, and installation.
Can one aerosol can insulate an entire floor?
That depends on the area and required thickness. The Loctite listing is aimed at gaps up to three inches but does not state a coverage figure, so it is better suited to targeted sealing unless the label confirms otherwise.