spray polyurethane foam, health and safety

Frequently Asked Questions (FAQs) for the
Do-It-Yourselfer

Do-It-Yourself (DIY) projects around the home can include small weatherization jobs using a convenient insulating foam sealant product in an easy to use, small can available at home improvement stores. This FAQ addresses insulating foam sealants, also referred to as one component foam (OCF) or “foam in a can.”

These FAQs do not address another kind of product called low pressure two-component spray polyurethane foam (SPF) often sold in kits. Low pressure SPF kits are typically used on larger scale, insulation projects, and are available to trained weatherization contractors and professional spray foam installers. Some DIYers occasionally express an interest in installing low pressure two-component foam themselves.  For more information, see our section for weatherization professionals. That weatherization professional section discusses a number of key issues, including training and personal protective equipment, including respirators, to consider before attempting to pursue a low pressure two-component SPF installation project yourself.  Note that some product manufacturers may limit the use of this product to spray foam professionals, or may also have specific training or other requirements to be met before these products can be used. For more information, see our section for weatherization professionals and CPI’s Statement on the Safe Use of Two-Component Low-Pressure Spray Polyurethane Foam.

Here are a few FAQs on insulating foam sealants: 

What is insulating foam sealant?
Insulating foam sealants are a type of spray polyurethane foam (one-component foam) that offer insulating, air sealing and adhering properties.  Insulating foam sealants are readily available at home improvement stores in small cans (typically 12-24 oz).  These products are intended for use in a “bead type” application for air sealing or adhering.  Their small volume, ease of use, and portability make them ideal for smaller projects tackled by the Do-It-Yourselfer (and often weatherization professionals). They are typically dispensed using a straw or small dispensing gun. These "canned" foam products have specific safety information on the label which should be carefully followed.

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Where can I apply insulating foam sealant?
Many home improvement centers and hardware retailers sell insulating foam sealant products (also known as one-component foam) in 12 to 24 oz. aerosol cans. These insulating foam sealants are useful for small DIY projects such as sealing holes, gaps and cracks around your home where air leakage could occur. Some possible areas to consider sealing include around:

  • window and door gaps
  • baseboards
  • vents
  • sill plates
  • pipe and duct penetrations
  • sink plumbing
  • floor/wall junctions and
  • around (not inside) electrical boxes

Insulating foam sealant is also effective for some exterior uses, such as:

  • where the siding meets the foundation
  • gas and electrical penetrations
  • garage ceiling and wall joints, and
  • around outdoor faucets and exterior vents

 It can even be used in some landscaping applications, such as:

  • stone wall repair
  • pond/waterfall fillers and repair, as well as
  • to secure landscape blocks

Follow the manufacturer’s instructions for application. It can be helpful for exterior applications to paint the surface to be treated with black paint (appropriate for outdoor use and the surface selected) to help prevent UV degradation and discoloration of the foam.

There are different grades of insulating foam sealants for different uses. Refer to the product label for information on appropriate product uses. For more information, see “Typical Uses for Insulating Foam Sealant.”

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Does the insulating foam sealant contain any hazardous ingredients?
The can contains a group of chemicals referred to as polymeric methylene diphenyl diisocyanate (pMDI) and a resin blend that may contain a mixture of polyols, catalyst (primarily amines), hydrofluorocarbon or hydrocarbon propellant, surfactants and flame retardants.  See the manufacturer’s label for specific product contents since they may vary slightly depending on the type of sealant.  When these chemicals combine, a reaction occurs to create the foam. Before the foam has sufficiently hardened, there may be potential for exposure to these chemicals.  Therefore, it’s important to follow the safety precautions and wear the protective equipment (glasses/goggles, gloves and full- coverage clothing) as described on the product label.

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How do I prepare the area where I’ll be applying the insulating foam sealant?
Just read and follow all instructions on the product label.  This includes following the product manufacturer’s instructions about ventilating the room in which the project will occur; wearing the personal protective equipment (generally, goggles or safety glasses, and gloves); wearing full-coverage clothing, such as a long-sleeved shirt, to minimize contact with skin.  In addition, the product manufacturer may recommend that the product not be used by children and that children not come into contact with the product.

For more details, see “Guidance on Using Insulating Foam Sealant.”

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Can I use too much? Is it possible to seal the house too tightly?
Given the small volumes of foam used when filling cracks and gaps in your home as a DIYer, it’s unlikely you will seal your house too tightly. However, you may want to consider discussing your project with an architect, building design engineer, weatherization professional or your local building code officials if you have questions. Proper ventilation in a home or building is very important. You may also wish to consider having a heating and cooling technician check large appliances (e.g., water heater, dryer) after air sealing to make sure they are venting properly.

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Do I need protective gear while applying insulating foam sealant, also known as “spray foam in a can”?
Yes, it is important that you wear protective gear often referred to as “personal protective equipment” (PPE) when applying insulating foam sealant (sometimes referred to as “one-component foam” or “foam in a can.” Wear the clothing and eye protection recommended by the product manufacturer on the label.  This can be safety glasses or goggles, full-coverage clothing, e.g., long sleeves; and gloves.

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Is it safe for others to be in the vicinity while I’m applying insulating foam sealant?
Follow the product manufacturer’s instructions.  Keep children and pets away from the area where you are applying the product.

When applying insulating foam sealant, a few considerations include:

  • Avoid getting foam on your skin or in your hair. (The foam is highly adhesive and very difficult to remove).
  • Provide plenty of ventilation to avoid breathing vapors and mist until the foam has hardened.
  • Refrain from smoking while spraying the foam.

For more details, see “Guidance on Using Insulating Foam Sealant.”

What should I do if the foam accidentally contacts my skin or eyes during application?
Refer to the product label for first-aid instructions. Keeping the instructions on the product label unobstructed (clearly readable) at the project site helps in the event that first-aid guidance is needed.

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How do I know the foam has cured or “hardened” so that my family can reenter the project area?
Generally, people can reenter the area when the insulating foam sealant has hardened to the point where it is considered “tack free” (no longer wet or sticky on the surface). The amount of time it takes for the foam to cure or harden varies depending on the product-specific formulation, temperature, humidity, the amount of foam being sprayed, and other variables. Typically, insulating foam sealants cure quickly at moderate temperatures and humidity. The foam surface cures first, and then gradually cures inside of the foam body. The thicker the foam is applied, the longer it takes to cure throughout. Spraying a mist of water on the substrate or/and between layers of foam can speed up the curing process. Typically, it can take between 5 and 60 minutes for the foam to become tack-free. Full cure may be reached in a time range of about 8 to 24 hours, depending on the product and site conditions. Consult the product label and instructions regarding cure times.

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Do I need to trim the foam? When can I trim it? 
Insulating foam sealants generally do not need trimming because the product is applied in a narrow “bead.”  However, if you wish to trim the applied product, it is good practice to wait until the foam has cured or hardened before attempting to trim it. Consult the product label and instructions for trimming information and cure times.

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How should I dispose of the trimmings from insulating foam sealant?
Cured foam trimmings may be disposed of as you would other household waste. Be sure to thoroughly clean up the work area after the job is completed. 

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What should I do if I smell an odor after SPF installation?
In the event you have concerns about odors that you believe may be related to the SPF insulation, you could contact your contractor and you may want to discuss the following: potential source(s) of the odor, that proper SPF installation procedures were followed, and a clean-up was completed.

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Does the cured sealant pose a fire hazard?  Is it flammable?
Insulating foam sealants typically contain flame retardants and when installed properly, are designed to meet all applicable building and fire code regulations  Installed cured product is combustible and will typically begin to thermally degrade at temperatures above 240ºF/116ºC.  In addition, the unreacted chemical constituents in the can may be combustible, so you should carefully read the instructions on the product label and follow them with respect to avoiding installations in areas exposed to high heat, such as around fireplaces, heaters, radiators, heat lamps, recessed lighting, bare copper wires, or inside electrical boxes.

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Can I leave the cured sealant exposed?
Generally, it is considered acceptable to leave cured or “hardened” insulating foam sealant exposed when it is used to seal small gaps and cracks. However, in the unlikely event that the foam sealant is used for larger area applications (e.g., greater than about 2 square feet), consider a consultation with your local building code official, or work with a professional weatherization or spray foam contractor, who understands local building code requirements for foam plastics.

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Does the insulating foam sealant help control moisture in my home?
Gaps and cracks in the building envelope can allow uncontrolled movement of moisture-laden air in and out of the building.  Loss of interior moisture control can make the interior air excessively dry or moist, which can cause occupant discomfort, poor indoor air quality, higher heating and cooling costs to control moisture, and in some cases, hidden deterioration of the building and possibly mold and mildew growth.  Air sealing these gaps and cracks with insulating foam sealant can help control interior moisture levels. See “Why select Insulating Foam Sealant” for more information on its many benefits.

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Can I use insulating foam sealant for arts and crafts projects?
Use spray polyurethane foam only for the uses described by the manufacturer on the product label. Please note that SPF products and insulating foam sealants are not intended for use by children. Check with the product manufacturer if you have questions about its intended use.

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What do I do with partially used or empty insulating foam sealant cans?
Empty cans may be disposed of as non-hazardous household waste. 

For full or partially used cans of insulating foam sealant, follow the product label instructions regarding storage and disposal.  The ingredients in the can are pressurized, so upright storage of the can at room temperature consistent with the manufacturer’s recommendations is important (avoid freezing or hot temperatures). Remember that the temperatures in a parked vehicle in the summer can rapidly reach very hot temperatures, so plan your purchase and transportation of the insulating foam sealant accordingly. 

After initial use, a partially used can of insulating foam sealant may be re-used for a limited time (typically up to 15 days) if stored in cool and dry conditions.

Disposal of full or partially used insulating foam sealant cans must be in compliance with all federal, state/provincial and local laws and regulations. Regulations may vary in different locations.  Call the product manufacturer for instructions.

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