How Long to Stay Out After Spray Foam Insulation

Short answer

Plan to be out of the house the whole time professional two-component spray foam is being sprayed, and for at least 24 hours after. That 24-hour figure is the common default cited by EPA, CPSC staff, the polyurethane industry's CPI and the manufacturers, with exhaust ventilation running throughout. Some products list other times at specific ventilation rates, so get the time for your exact product in writing before the job starts.

Key points

Everyone without protective gear leaves while foam is sprayed, pets included.
24 hours is the usual minimum for high-pressure, two-component foam. Low-pressure kits and cans have their own times.
Manufacturers call for exhaust ventilation during spraying and for at least 24 hours after. Some products list a longer or shorter time tied to a set ventilation rate.
Re-entry (trained workers in protective gear) and re-occupancy (everyone else) are separate clocks.
People with asthma, respiratory allergies or isocyanate sensitivity should review the product information with their doctor before the job.

How long to stay out after spray foam: the guidance

Every official source says the same two things: leave while it's sprayed, and follow the manufacturer's time before coming back. Manufacturer documents differ in the details, so the rows below show several of them side by side.

Source	What it says
EPA Safer Choice	Occupants and other trades should vacate during installation. For two-component high-pressure foam, some manufacturers recommend 24 hours before re-occupancy.
CPSC staff fact sheet	Residents should vacate "for at least 24 hours." Agree on the re-occupancy time with your contractor before the job starts.
CPI (American Chemistry Council)	Wait "a minimum of 24-hours" after high-pressure spray foam; recommendations may vary. Some low-pressure kits list one hour.
BASF WALLTITE HFO guidelines (Feb 2023)	"24-hour re-occupancy time is advised." Ventilate during and after application.
Carlisle Foamsulate Closed Cell guide (July 2021)	Mechanical ventilation during spraying and for 24 hours after, at no less than 0.3 air changes per hour.
Huntsman re-occupancy agreement (May 2023)	Everyone, including air-breathing pets, vacates. Negative-pressure ventilation during spraying and for 24 hours after. A few products list different times at set ventilation rates.
Johns Manville Corbond IV guide (Canada)	Occupants stay separated from the spray area for 25 hours, with ventilation for 25 hours; other trades may re-enter at 12 hours.

The pattern: 24 hours is the common default for professional two-component foam, a few products list a different time, and the number isn't always on the data sheet. It may sit in a separate re-occupancy document or the application guide. Ask for the time for the exact product on your quote, and where it comes from.

What happens before, during and after spraying, and when occupants and pets come back.

Why there's a waiting period

Spray foam firms up in seconds, which makes it look finished. EPA cautions that tack-free foam "still contains unreacted SPF chemicals," and that curing time depends on the product, thickness, temperature and humidity. During spraying, vapors and aerosols can travel through a building that isn't isolated and ventilated.

That's why the clock starts when spraying stops, and why it assumes the exhaust ventilation actually ran. EPA's own page is candid that "it is not clear how much time is needed" in every case, which is why it defers to the manufacturer's number for the specific product.

Occupants vs. workers

Manufacturers set two different times.

Re-entry is for sprayers, helpers and informed trade workers. One manufacturer's re-occupancy agreement requires anyone present during spraying, or within 24 hours after it, to wear full-body protective clothing and a supplied-air respirator. Another's Canadian guide lets other trade workers back in at 12 hours.
Re-occupancy is for everyone else: you, your family, your pets, and any trades who aren't trained and equipped.

CPSC staff note that some manufacturers let workers back in without respirators or gloves after 24 hours. Trimming foam early carries its own risk: EPA warns that dust from cutting foam during the tack-free phase can contain unreacted isocyanate.

On new construction, CPI points out that re-occupancy matters less because foam usually goes in well before anyone moves in. The worker re-entry time still applies to the electricians and drywall crew.

Pets, kids and people with asthma

Pets: Manufacturer re-occupancy terms can name "air breathing pets" outright, so dogs, cats, birds and small animals leave with you. CPI also lists clearing pets from the area before spraying.
Children: EPA calls children with asthma "an especially vulnerable population," and notes that kids crawl and sit where dust settles. The site should be fully cleaned before they come back.
Asthma, allergies and sensitization: CPSC staff advise people with asthma, respiratory allergies, skin conditions or prior isocyanate sensitization to review the product information carefully, and say some may want to consider a different insulation. Talk it over with your doctor before the job. CPSC also notes that re-occupancy can vary depending on whether children or elderly people live in the home.

What a good installer does

Use this as a checklist. It draws on EPA's ventilation guidance, CPI's homeowner guidance and manufacturers' instructions.

Gives you the re-occupancy time for your product in writing before the job.
Isolates the work area with plastic sheeting and taped seams.
Shuts down the heating and cooling system and seals its openings in the work area.
Runs exhaust fans that keep the work area under negative pressure, venting outside to a safe spot. EPA's rule of thumb is exhaust capacity about 10% greater than supply.
Posts warning signs at entrances and keeps out anyone without protective gear.
Removes or covers absorbent belongings, and puts out ignition sources such as pilot lights in the work area and next to it.
Keeps ventilating for at least 24 hours after spraying, or longer if the product calls for it.
Cleans up dust and trimmings before you return, then restarts the HVAC system.

Coming home

When you walk back in, a mild smell near the foam is common and should fade over the next few days. A strong odor, or foam that looks discolored, sticky or shrunken, is a reason to call the installer. See spray foam smell, off-ratio spray foam and how to spot bad spray foam.

Don't sand, cut or heat the foam yourself. If a basement or attic will become living space, the foam needs a covering first; see thermal barrier vs ignition barrier.

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FAQ

Can I stay home if they're only spraying the basement or attic?

Plan on no. EPA notes that vapors can migrate through a house that isn't isolated and ventilated, and manufacturer re-occupancy terms can require everyone to vacate the building, not just the room. Follow the terms for your product.

Is the wait different for open-cell foam?

It depends on the product. Some manufacturers list different times for different open-cell foams, tied to specific ventilation rates, so ask for the time for the exact foam on your quote.

What about spray foam from a can?

One-component cans are a different product. EPA cites manufacturer estimates of about 8 to 24 hours for them to cure; follow the label. Two-component DIY kits have their own times too; see DIY spray foam kits vs professional install.

When can the heat or air conditioning go back on?

EPA's guidance is to restart it only after the foam has cured and the area has been ventilated and cleaned.