“Does spray foam smell” is one of the most common questions homeowners ask our contractors, and the answer is simple: Yes! Far too often SPF contractors are a little too eager to get the job and say otherwise. Do you know the number one problem that SPF manufacturers and the EPA are called about? Spray foam odor. The EPA has even put together a website regarding the use of SPF.
Although properly installed SPF from quality SPF manufactures has little to no odor when fully cured, there are some odors during the installation process and for some time after the install. How long the odors are present varies depending on what happened during the installation process. With closed cell foam, care must be given not to exceed the maximum recommended pass thickness of 2”. Spraying CC SPF in thicker passes will generate more heat in the cells of the foam and can result in lighter density foam with more open cells and create more amines than would be created with a proper 2” pass. We all know that off ratio (resin rich) foam can cause odors. While dirty filter screens, transfer pump and/or proportioner pump issues can cause off ratio foam there can be other causes. Poorly mixed foam from spraying at too low a temperature and/or too low a pressure can cause an off ratio situation. Moisture present on the substrate can react with some of the isocyanate in the foam. If and when this happens there is not enough iso to react off all of the resin resulting in resin rich foam.
In additions to these concerns, proper ventilation is also needed during the spray foam install. Care should be taken to establish a negative pressure in the work area. Plenty of air flow will help get the odors out of the building before they have time to penetrate the porous wood, fibrous insulations, or anything else in the spray area that can possibly absorb odor. The EPA has come out with a ventilation guidance document that can be very helpful.
Every once in a while, despite doing a flawless application, you wind up with a customer that has a very acute sense of smell, that has done an internet search on spray foam odors and gets very concerned. This can be very problematic for the spf installers. What do you do? Homeowner communication is key from day one. Before the job, when asked if spray foam smells, you need to answer yes! SPF has an odor during the application process and for some time after. How long the smell lasts will vary from person to person, and job to job. Everyone’s sense of smell is different. Explain that at every step in the construction process odors are present. When concrete is poured, there is an odor. That odor is replaced by the wood smell of the framing. PVC plumbing cement has an odor. If they use fiberglass, not only will they itch, but there will be an odor. Cellulose has an odor. That odor is replaced by the drywall, and it goes on and on through the rest of the construction process; joint compound or plaster, paint, carpet or vinyl adhesives, urethane on finish wood, glue in finish cabinetry, caulking, etc. The important thing to communicate is that smells are a normal part of construction, and are nothing to worry about on their own.