Getting Started

Your Guide to Using Low Pressure Two-Component Spray Polyurethane Foam (SPF)

Here are a few key considerations for using low pressure two-component SPF.

Planning Ahead

  1. Do your research first: Analyze the type of air sealing job you have.
  2. Research building code requirements. This will help you select the right SPF for the job. Don’t forget to consult with the manufacturer to determine that the SPF is appropriate for the job.
  3. Inspect the SPF kit: After the low pressure SPF kit has been ordered and has arrived, inspect it for integrity.  The containers or cylinders should be intact and undamaged.  Find the instructions and Material Safety Data Sheet for the product.
  4. Review and follow the manufacturer’s directions
  5. Locate and review the manufacturer’s Material Safety Data Sheet (MSDS) for the SPF product, and follow all instructions.  If you are an employer, note that you have obligations under the Occupational Health and Safety Act to provide a safe workplace for your employees.  An employer has an obligation to provide appropriate training and personal protective equipment, among other obligations.
  6. Handle and store the kit following manufacturer’s instructions: Follow the manufacturer’s instructions about storage of the material.  It is important to follow the manufacturer’s instructions about temperature and storage because pressurized products like the chemicals contained in the cylinders should not be exposed to open flame or high temperatures because high heat can lead to a container explosion.
  7. Identify and obtain the Personal Protective Equipment appropriate for the job: Low pressure two-component foam is installed with the use of PPE that protects workers or users from the chemicals that are mixed and reacted to make the finished foam.
  8. Importance of Skin Protection: One of the chemicals in the kits is called MDI, an isocyanate for which protection is needed.  The spray foam application for low pressure two-component foam puts enough MDI in the air that skin protection and eye protection are indicated for use.
  9. Importance of a Respirator: In addition, conditions and potential exposures from some low pressure two-component foam applications may trigger OSHA requirements to use respiratory protection (a respirator). In some cases, depending on the job application, the appropriate respirator will be one certified by the U.S. National Institute of Occupational Safety and Health (NIOSH).  OSHA requires users of certain respirators to have an advance medical evaluation, fit testing and training. Employers should make sure that they understand and are compliant with all applicable OSHA requirements.
  10. Discuss project scope and safety measures with occupants: Low pressure two-component SPF application involves the potential for exposure to a variety of chemicals, including modified methylene diphenyl diisocyanate (MDI) and other SPF chemicals.  SPF can be applied safely with appropriate PPE and other measures.
  11. Develop a job plan specific to your installation that takes into consideration all relevant factors like the size and ventilation at the job site; whether the site is outdoors or indoors; potential physical hazards at the job site; how to close the job site and vicinity to improperly outfitted workers; and safe handling of all chemicals that may be on the job site, like solvents and paints


Here’s some sample guidance offering suggested topics you may wish to discuss with homeowners or occupants while planning for the job. In commercial and public buildings, you may choose to provide outreach to building owners or their designee, as well as to individual tenants.

Include reoccupancy as part of your job plan:  An important part of your planning and discussion with the building owners or homeowner, addresses reoccupancy.  Occupants do not have the benefit of PPE, so it is incumbent on the contractor to advise them how long to leave the job area, how far away they need to be, and when they can reenter.Reoccupancy time after a low pressure two-component SPF interior application is dependent on a number of factors, including SPF formulation, the amount of foam applied for the volume of space, the degree and effectiveness of ventilation, and other variables. And it should be noted that in addition to the release of airborne SPF chemicals during spray application, certain components can be liberated from some newly-installed SPF products for a short period of time following installation.

Consult with the product manufacturer to determine the appropriate reoccupancy time for the particular job and SPF in use.  You can also consult the evaluation reports for specific SPF insulation products, which often include a recommended reoccupancy time.

Preparing the Spray Area

Prepare the surface:Clean dirt or oil from the surface to be sprayed.

Protect from overspray:Cover surrounding areas to protect from overspray.  This is often done by covering exposed objects or surfaces with plastic sheeting, securely taping the sheeting in place, or by moving mobile objects out of and an appropriate distance away from the job site.  The foam will adhere to almost everything, including plastic, rubber, glass, and skin (although skin should not be exposed).  Foam mist can travel on air currents from fans, ventilation, and wind, so plan accordingly.

Shut off ignition sources:Be thoughtful about addressing potential combustion risks.  Extinguish heat sources, sparks and open flames in the spray area, adjacent rooms and behind neighboring walls. This includes pilot lights to gas stoves, dryers, furnaces and water heaters. Keep area free from ignition sources until fumes have dissipated. Don’t forget to think about other things at the job site, like paints and solvents that can present combustion risks, and address those too.  Refrain from smoking on the job site.

Isolate the work area and ventilate:Good ventilation of the work area is an important part of the job.  As you prepare the job site, evaluate opportunities to maximize good ventilation.  Open windows and doors, watching for air currents coming in and out of the job area.  Additional ventilation measures, like fans, can also improve ventilation and disperse vapors.

Applying Foam Using Low Pressure Two-Component Kits Systems

Restrict access: During the job, and for the appropriate reoccupancy period following the job, only appropriately trained persons wearing proper PPE should be in the job area.  A useful tool to help this is to mark the job site off with signs and tape, and advise occupants that the job will be in progress and they should stay out of the job site during designated hours.  Be thoughtful that children and pets could wander into the site without regard to signs and tape, or others may not be able to read and understand signs, so take appropriate advance measures to avoid having non-authorized persons or animals entering the work site.

Wear Appropriate Personal Protective Equipment (PPE): It is important to wear the proper PPE prescribed by the product manufacturer to avoid potential exposure to SPF chemical ingredients. Appropriate PPE for low pressure two-component applications includes safety goggles/glasses, appropriate gloves, and full-coverage clothing that protects the skin.  Avoid getting foam on your skin or in your hair. At times, you may be required to use respiratory protection.

Read our Safety Instructions