How to Read a Spray Foam Technical Data Sheet

A spray foam technical data sheet packs a lot into one page: a product description, a column of test methods, a column of numbers and a block of processing settings at the bottom. Most people skim straight to R-value and stop. That's a mistake, because nearly every row on the sheet tells you something that matters on the job — where the foam belongs, how it handles moisture, what the inspector will ask for and how to set up the rig.

This guide walks through a data sheet row by row, using the real values from our two products — ComfortSeal 500 open cell and ComfortSeal HFO closed cell — as the worked example. Every figure below comes from the evaluation reports and data sheets, and both are free to download from our Tech Library if you want to follow along.

Start with the product description

The paragraph at the top is easy to skip, but it sets up everything else. It tells you what kind of foam you're dealing with before you look at a single number.

• ComfortSeal 500 is a two-component, light density, semi-rigid, water-blown 0.5 lb open cell foam. It expands roughly 100 times its liquid volume.
• ComfortSeal HFO is a two-component, medium density, semi-rigid 2 lb closed cell foam that uses an HFO blowing agent with a global warming potential of 1. It expands roughly 15 times.

Expansion alone tells you something practical: open cell grows fast and fills big volumes, while closed cell builds up in a denser, more controlled layer.

Thermal performance: R-value and ASTM C518

R-value measures resistance to heat flow — higher is better. Data sheets report it using ASTM C518, a heat flow meter test on a foam specimen. The data sheet gives a 1-inch figure, and the IAPMO evaluation reports show how the per-inch value changes with depth: ComfortSeal 500 gives R-4.1 per inch at 1 inch, falling to R-3.5 to R-3.7 per inch from 3.5 to 14 inches, and ComfortSeal HFO gives R-7.3 per inch at 1 inch, falling to R-7.0 to R-7.1 per inch from 3.5 to 12 inches (ER-974 and ER-975, Table 1). 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.

So the 1-inch figure is not the number for a wall. For thicker installations, use the tables in the IAPMO evaluation reports instead of multiplying: ComfortSeal 500 is R-13 at 3.5 inches, and ComfortSeal HFO is R-25. We explain why in spray foam R-value by thickness.

Physical properties: what the foam is made of

The middle of the sheet describes the foam's physical makeup. Here are the rows, the tests behind them and what they mean when you're standing in front of the wall.

• Core density is the weight of the cured foam per cubic foot, measured from the core of a sample. It's the "half-pound" and "two-pound" you hear on job sites, and it drives most of the other properties.
• Cell content tells you whether the tiny bubbles in the foam are mostly open or mostly closed. Open cells make a soft, vapor-open foam; closed cells make a rigid foam that resists vapor and water.
• Compressive strength is how much pressure the foam takes before it crushes. Tensile strength is how hard you can pull on it before it tears apart. ComfortSeal HFO's higher values are why closed cell is chosen where a rigid, durable layer is wanted.
• Dimensional stability reports how much a sample changes in size after aging under heat and humidity. Smaller is steadier.
• Water absorption shows how little water closed cell takes on, and fungi resistance reports whether fungus grew on the foam under test — for ComfortSeal HFO, none did.

A dash in the table simply means that row isn't reported on that product's data sheet. Don't fill in the blank with a guess.

Moisture, air and sound

Water vapor permeance (ASTM E96) tells you how easily water vapor passes through the foam, in perms. Lower means less vapor gets through. ComfortSeal 500 is 21 perms at 1 inch — vapor-open, so assemblies can dry toward the interior. ComfortSeal HFO is 0.45 perms at 2 inches, which makes it a Class II vapor retarder (the class that covers materials between 0.1 and 1.0 perm). Always note the thickness a perm figure is quoted at, because permeance depends on how thick the layer is.

Air leakage (ASTM E283) measures how much air moves through the material. ComfortSeal 500's data sheet reports less than 0.002 L/s·m². The ComfortSeal HFO data sheet doesn't publish an air leakage figure, so we don't quote one for it.

Sound appears on the ComfortSeal 500 sheet: a noise reduction coefficient of 0.75 (ASTM C423) and a sound transmission class of 39 (ASTM E413). That's why open cell is the usual pick for interior walls and media rooms.

Wind uplift (UL 1897) appears on the ComfortSeal HFO sheet: 210 psf. It's one reason closed cell is favored in storm-prone areas — see our guide to spray foam in humid coastal climates.

Fire performance rows

Both products report Class I on ASTM E84: a flame spread index of 25 or less and a smoke developed index of 450 or less, tested at up to 4 in. That's a surface-burning rating for the foam itself. It is not permission to leave the foam exposed: a foam plastic still needs a thermal barrier where people live, or an ignition barrier in service-only attics and crawl spaces, unless the evaluation report lists an alternative.

The next two rows are the ones inspectors ask about: thermal barrier (NFPA 286) and ignition barrier (ICC-ES AC377 Appendix X). ComfortSeal 500 has a listed coating for both (DC315 for either; No-Burn Plus ThB for the ignition barrier) at the thickness in its evaluation report; ComfortSeal HFO needs no ignition barrier coating in service-only attics and crawl spaces, within the report's thickness limits, and passed NFPA 286 for 15 minutes with a coating. Those results have enough nuance to deserve their own article: ignition barrier vs. thermal barrier.

Processing parameters: the rig settings

The bottom of the sheet is for the spray rig operator. These are the manufacturer's application conditions, and running outside them risks foam that doesn't perform the way the rest of the sheet describes.

Mix ratio and pressure keep the two components blending properly at the gun. Heater and hose temperatures keep the chemicals at the right viscosity. Substrate temperature and moisture limits protect adhesion and foam quality — a cold or wet surface is a common cause of foam that doesn't stick or cure the way it should. Notice that the two products run at different temperatures; don't carry one product's settings over to the other.

Storage and shelf life

Near the processing block you'll usually find a storage temperature and a shelf life for the unopened drums. They matter because the chemistry drifts if drums sit hot, cold or too long, and foam sprayed from out-of-date material won't match the rest of the sheet. For ComfortSeal HFO, ER-975 Section 4.1 calls for drums stored at 70 to 80°F in factory-sealed containers, with a maximum shelf life of six months. The ComfortSeal 500 data sheet lists storage at 50 to 80°F, with a shelf life of one year for the A-side (ISO) and six months for the B-side (resin). Check the date on the drum label against those figures before a job, and ask your supplier how the material was stored.

Where the data sheet stops and the evaluation report starts

A data sheet is the manufacturer's summary of test results. An evaluation report is an independent document written for building officials. For ComfortSeal, that's IAPMO UES ER-974 for ComfortSeal 500 and ER-975 for ComfortSeal HFO. The report is where you'll find R-values at installed thicknesses and the conditions of use an inspector will hold you to.

Contractors, builders and architects can find both products side by side on our products page, or contact our team with questions about a specific row.