Is Spray Foam Insulation Safe?

Is spray foam insulation toxic after it cures and dries?

Tested products give off no significant VOC levels once cured, the trade group says. The Spray Polyurethane Foam Alliance FAQ page (updated April 2026) says: "Several SPF products have been independently tested (ULe GreenGuard, CAN-ULC 774, CA 01350) for release of volatile organic compounds, and no significant levels have been measured after the prescribed cure periods."

Cured foam still needs care in three cases:

• Heat and flame. The same SPFA page (2026) says: "SPF, like many construction materials, is combustible, and can ignite when subjected to heat or flame."
• Hot work. The SPFA Health and Safety page (updated 2025) says contractors typically post a "No Hot-Work" sign to keep welding and open flames away from the foam until its fire covering is on.
• Burning or charring. The OSHA Isocyanates page (read October 2026) lists "the thermal degradation of polyurethane products" among the work that may involve isocyanate exposure.

The SPFA ties its VOC result to tested products and their prescribed cure periods. Ask for the test listing of the product your contractor plans to spray.

What chemicals are in spray foam insulation?

Spray foam is two liquids that react on site and give off heat. The Spray Polyurethane Foam Alliance Health and Safety page (updated 2025) says the "A" side is commonly MDI and pMDI, two isocyanates. It says the "B" side "is typically a blend of polyols, catalysts, blowing agent, flame retardant, and surfactant."

The OSHA Isocyanates page (read October 2026) says: "Isocyanates are the raw materials that make up all polyurethane products." The same OSHA page (2026) says health effects of exposure "include irritation of skin and mucous membranes, chest tightness, and difficult breathing." It adds: "The main effects of hazardous exposures are occupational asthma and other lung problems, as well as irritation of the eyes, nose, throat, and skin."

The SPFA sorts spray foam by how it is applied:

Source: Spray Polyurethane Foam Alliance, FAQs, updated April 2026, read October 2026.

What is the difference between open-cell and closed-cell spray foam?

Open-cell foam is soft and light, and closed-cell foam is dense and rigid. The Spray Polyurethane Foam Alliance FAQ page (updated April 2026) puts open-cell foam at about 0.5 to 0.8 pounds per cubic foot, with an R-value that "typically ranges from R3.6 to R4.5 per inch." Closed-cell foam runs 1.8 to 2.3 pounds per cubic foot and R5.8 to R6.9 per inch, per the same 2026 page, which says to consult product data sheets.

The 2026 SPFA page says closed-cell foam "is the only spray foam that can be used where contact with water is likely," such as below grade concrete walls. It says open-cell foam is moisture permeable "and may require the installation of a vapor retarder in colder climates." The page gives one re-occupancy note for spray foam in general, so the safety steps below apply to either one.

How long should you stay out of the house after spray foam is installed?

Stay out until your contractor clears the work area, typically 24 hours. The Spray Polyurethane Foam Alliance FAQ page (updated April 2026) says: "Because of these short-term airborne levels, re-occupancy of the work area by other trades or building occupants is typically 24 hours."

The same 2026 page says the time "may vary depending on type of material, volume of mists and fumes generated, building size and rate of ventilation." It also says: "Your contractor and their supplier can recommend re-occupancy times based on job specific conditions."

During and just after spraying, the SPFA page (2026) says access "should be restricted to personnel wearing appropriate personal protective equipment (PPE), including respirators." Get the re-occupancy time for your product in writing before the job is booked, and plan where everyone in the house will stay.

Who and where should not use spray foam insulation?

Nobody without a respirator and protective gear belongs in the work area while foam is sprayed. The Spray Polyurethane Foam Alliance FAQ page (updated April 2026) restricts that area to workers in PPE whose jobs require them to be there.

If someone in the house would rather avoid spray foam chemicals, tell your contractor before the job is priced. Our Basic level is a blown in top up with air sealing and does not use spray foam.

Spray foam should not be left bare in a finished room. Section R316.4 of the 2021 Seattle Residential Code requires a thermal barrier such as 1/2-inch gypsum wallboard. Open-cell foam should not go where it will stay in contact with water, since the SPFA page (2026) names closed-cell as the only spray foam for those spots.

Does spray foam insulation need to be covered for fire safety?

Yes, in living space. The 2021 Seattle Residential Code, Section R316.4 (Chapter 3, PDF page 58), says: "Unless otherwise allowed in Section R316.5, foam plastic shall be separated from the interior of a building by an approved thermal barrier of not less than 1/2-inch (12.7 mm) gypsum wallboard, 23/32-inch (18.2 mm) wood structural panel or a material that is tested in accordance with and meets the acceptance criteria of both the Temperature Transmission Fire Test and the Integrity Fire Test of NFPA 275."

Attics and crawl spaces have their own rules. Sections R316.5.3 and R316.5.4 drop the thermal barrier when three things apply: the code requires an access opening, the space is entered only for repairs or maintenance, and the foam is tested under Section R316.6 or covered by an ignition barrier. Listed ignition barriers include 1-1/2-inch mineral fiber insulation, 1/4-inch wood structural panels and 3/8-inch gypsum board.

In a finished room, 1/2-inch drywall is one of the three thermal barriers R316.4 allows. Drywall work for wall insulation is not in our starting prices, and we price it in writing when a job needs it. A garage wall shared with the house has its own fire rule; see How to Insulate a Garage: A Step-by-Step Guide.

Is DIY spray foam insulation safe?

Cans for small gaps are sold for DIY use; spray foam insulation is a trained trade. The Spray Polyurethane Foam Alliance FAQ page (updated April 2026) says one-component cans "are used for sealing cracks, crevices and small holes" and "are popular for do-it-yourself (DIY) projects."

For high pressure foam, the same 2026 page says: "Improper application of the product can result in chemical exposure to the applicator, as well as the occupants of the structure being insulated. Application of the product without proper training is not recommended." It also warns that closed-cell foam sprayed at several times the manufacturer's thickness limits "can generate enough heat to self-ignite the foam."

The OSHA Isocyanates page (read October 2026) lists foam-blowing, and the manufacture of insulation materials, among the jobs that may involve isocyanate exposure.

What should you ask a spray foam contractor before the job?

Ask about training first. The Spray Polyurethane Foam Alliance FAQ page (updated April 2026) says the applicator "should have completed a two or three day equipment and materials course" from the material supplier or distributor, at a minimum. Questions that follow from the SPFA pages:

• Has every crew member completed the Online Health and Safety Training for SPF from the Center for the Polyurethanes Industry?
• Which product will you spray, and what re-occupancy time do you and your supplier give for this job?
• How will you keep people without respirators out of the work area during and after spraying?
• Which thermal or ignition barrier will cover the foam, and can I see its code compliance report?

The SPFA Health and Safety page (updated 2025) says: "Consumers should be informed about the products used and ensure code compliance reports are available." A radiant barrier is a different product with no spray chemistry; see How to Properly Install Radiant Barrier Insulation.

How much does spray foam insulation cost in the Seattle area?

Spray foam starts at $15,000+ for an attic up to 1,500 sq ft, $16,000+ for a crawl space and floor and $40,000+ for a whole house. Spray foam is the Luxury level on Insulation Installation Services Across the Greater Seattle Area, and it seals air and insulates in one step. Blown in insulation costs less; every attic level and what it includes is in How Much Does Attic Insulation Cost?

We price every job in writing after a site visit. For our work in the city, see Home Remodeling Contractors in Seattle, WA.

Source: Insulation Installation Services Across the Greater Seattle Area, Luxury level, October 2026. The level includes spray foam insulation, a full air seal in one step, higher R value per inch, moisture control, rim joists sealed and a before and after report. Not included in starting prices: asbestos or vermiculite removal, rodent cleanup beyond normal debris, electrical repairs found during the work and drywall work for wall insulation.

What if spray foam still smells after installation?

Call the contractor first. The Spray Polyurethane Foam Alliance FAQ page (updated April 2026) says some foams "may give off a noticeable odor for several days after application," usually from unreacted amine catalysts, and recommends extra ventilation of the work area for a few days.

The same 2026 page says other odors that are "present or persistent," or foam that is discolored, sticky or friable, are symptoms of improperly installed foam, and to contact the SPF contractor. If the contractor does not resolve it, the SPFA page (2026) says the building owner should contact the supplier of the foam.

Our insulation work carries a 2-year workmanship warranty, extendable to 5 years, and the materials carry the manufacturer's warranty.