ComfortSeal 500 Open Cell Spray Foam Insulation
ComfortSeal 500 is a two-component, water-blown, 0.5 lb/ft³ open-cell spray polyurethane foam insulation made by USAFoam, LLC. It is R-13 at 3.5 inches and R-20 at 5.5 inches (IAPMO ER-974, Table 1), Class I for flame spread and smoke (ASTM E84), NRC 0.75 and STC 39, and is installed by ComfortSeal-certified contractors.
The air-sealing, sound-dampening workhorse. A light density open cell foam that expands roughly 100 times on contact to fill the cavity around wiring, outlets and irregular framing — then cures semi-rigid and stays vapor-open so the wall can dry.
Every number, with its test method
Transcribed from the ComfortSeal 500 technical data sheet and IAPMO ER-974.
| Property | Value | Test method |
|---|---|---|
| R-value at 3.5 in. (2x4 wall) | R-13 | ASTM C518; ER-974 Table 1 |
| R-value at 5.5 in. (2x6 wall) | R-20 | ASTM C518; ER-974 Table 1 |
| R-value per inch | R-4.1 at 1 in., falling to R-3.5 to R-3.7 at 3.5 to 14 in. The R-value per inch of this insulation varies with thickness. The thicker the insulation, the lower the R-value per inch. The higher the R-value, the greater the insulating power. Ask your seller for the fact sheet on R-values. | ASTM C518 |
| Core density | 0.5 lb/ft³ | ASTM D1622 |
| Open cell content | >97% | ASTM D6226 |
| Tensile strength | 5.19 psi | ASTM D1623 |
| Water vapor permeance | 21 perms at 1 inch | ASTM E96 |
| Air leakage rate | <0.002 L/s·m² | ASTM E283 |
| Noise reduction coefficient | 0.75 | ASTM C423 |
| Sound transmission class | 39 | ASTM E413 |
| Dimensional stability | <5% | ASTM D2126 |
Per-inch range from IAPMO ER-974, Table 1. Specifications verified against IAPMO ER-974 on September 29, 2026.
Fire test data
Evaluated under IAPMO Uniform Evaluation Service report ER-974.
ER-974 also lists ComfortSeal 800, which is not offered under the ComfortSeal brand at this time.
| Test | Result | Method |
|---|---|---|
| Flame spread | Class I — pass (≤25), tested at up to 4 in. | ASTM E84 |
| Smoke developed | Class I — pass (≤450), tested at up to 4 in. | ASTM E84 |
| Thermal barrier | Prescriptive ½-in. gypsum at any thickness, or DC315 at 18 wet / 12 dry mils — foam up to 8 in. on walls, 14 in. on ceilings (ER-974 Table 4) | NFPA 286 |
| Ignition barrier | Prescriptive ignition barrier at any thickness, or DC315 at 6 wet / 4 dry mils (foam up to 9.5 in. on walls, 14 in. on ceilings) or No-Burn Plus ThB at 4 wet / 3 dry mils (up to 10 in. on walls, 14 in. on ceilings) (ER-974 Table 5) | ICC-ES AC377 App. X |
How much R you get at each depth
IAPMO ER-974, Table 1. Values are calculated from tested k-factors at 1 and 3.5 inches, at a 75°F mean temperature.
| Installed thickness | R-value |
|---|---|
| 1 in. | R-4.1 |
| 3.5 in. (2x4 wall) | R-13 |
| 4 in. | R-14 |
| 5.5 in. (2x6 wall) | R-20 |
| 7.5 in. | R-27 |
| 9.5 in. | R-34 |
| 11.5 in. | R-42 |
| 14 in. | R-51 |
Installed thickness in inches · thickness steps are not evenly spaced
Go deeper on open cell foam
Best applications
Interior walls
Expands around wiring, outlets and framing so the wall stops leaking air.
Attic rooflines
Moves the attic inside the conditioned space where the climate allows (ER-974 §3.3.4.1, IRC R806). Install with an ignition barrier.
Sound control
An NRC of 0.75 absorbs noise between bedrooms, media rooms and floors.
Retrofit and renovation
Expands to fill irregular cavities in older framing that are awkward to fit with batts.
Processing parameters
Starting targets. Temperatures and pressures vary with ambient conditions, substrate, humidity, elevation and equipment — watch the foam and adjust.
| Parameter | Target |
|---|---|
| Mixing ratio | 1 : 1 by volume |
| Processing pressure | 1200–1350 psi |
| Primary heater and hose | 125–130°F (52–55°C) |
| Recirculation | 75–90°F (24–32°C) |
| Substrate and ambient | Above 32°F (0°C) |
| Substrate moisture | Below 18% |
| Maximum per pass | 6 inches (IAPMO ER-974 §3.3.2) |
| Liquid component | A-side (ISO) | B-side (resin) |
|---|---|---|
| Color | Brown | Amber |
| Viscosity at 77°F | 185–235 cps | 250–390 cps |
| Specific gravity | 1.25 | 1.14–1.19 |
| Storage temperature | 50–80°F | 50–80°F |
| Shelf life, unopened | 1 year | 6 months |
ComfortSeal 500 FAQ
What is the R-value of ComfortSeal 500?+
IAPMO ER-974 lists R-13 at 3.5 inches, R-20 at 5.5 inches and R-27 at 7.5 inches, calculated from k-factors tested to ASTM C518. The chart on this page shows every depth from 1 to 14 inches.
Is ComfortSeal 500 a vapor barrier?+
No. It measures 21 perms at 1 inch, so it stays vapor-open and lets an assembly dry to the interior. Where the code calls for a vapor retarder, one is installed with it (IAPMO ER-974 Section 2.5).
Does it need an ignition barrier in an attic?+
Yes. In an attic or crawl space entered only to service utilities, ComfortSeal 500 is covered with a prescriptive ignition barrier, or with DC315 at 6 wet mils (4 dry) for foam up to 9.5 inches on walls and 14 inches on ceilings, or No-Burn Plus ThB at 4 wet mils (3 dry) for foam up to 10 inches on walls and 14 inches on ceilings, per IAPMO ER-974 Table 5.
How much does it help with noise?+
It carries a noise reduction coefficient of 0.75 (ASTM C423) and a sound transmission class of 39 (ASTM E413).
Is ComfortSeal 500 evaluated for code compliance?+
Yes. It is evaluated under IAPMO Uniform Evaluation Service report ER-974, and is Class I for flame spread and smoke developed under ASTM E84.
Is there a ComfortSeal 800?+
IAPMO ER-974 also lists a ComfortSeal 800 formulation. It is not offered; ComfortSeal 500 is the open-cell product available.
Ready to spray ComfortSeal 500?
Talk to our team about pricing and supply, or find a certified installer for your project.