FAQ

Spray foam insulation, additionally known as spray polyurethane foam insulation, is a product that is applied with a sprayer that mixes two liquids. The foam expands to fill cavities and cover surfaces completely, and it can be used to insulate in walls, attics, ceilings, floors, and basements and crawlspaces. The two liquids contain the following: “methylene diphenyl diisocyanate (MDI) and polymeric methylene diphenyl diisocyanate (pMDI), polyols, catalysts, blowing agent, flame retardant, and surfactant.”

The difference between spray foam and more common forms of insulation like fiberglass or cellulose is that spray foam insulation is an air barrier and thermal barrier all in one (with closed cell spray foam even offering a moisture barrier as well). This means that spray foam insulation does the job of providing insulation and air sealing with one product, whereas traditional forms of insulation do not provide any barrier to the flow of air. This is important for establishing a continuous and complete thermal/air barrier with the building envelope.

There are two different types of spray foam insulation: open cell and closed cell. Closed-cell spray foam cures into a complex, rigid state, whereas open cell cures with a spongy, softer feel to it. In terms of R-values, closed-cell spray foam is close to R-7 per inch and open cell around R-4 per inch. Also, closed-cell becomes an air barrier at only 1” of application, while it takes on average 3” of open-cell foam to achieve an air barrier. Another big difference in the two is that open-cell is water permeable and closed-cell is not. Open-cell also has soundproofing qualities that can help in dampening outside noise.

While every job and application can be different, we generally suggest open-cell spray foam for attic encapsulations and closed-cell spray foam for basement or crawlspace encapsulations. Open-cell spray foam works best in attics because of its ability to permeate moisture, meaning that if you do have a roof leak, the water would pass through it and enable you to see the issue. Because closed cell spray foam is not water permeable, we do not usually recommend it for attic applications since it could trap moisture from a leak and potentially cause issues like rot and damage to your roof. Some applications where closed-cell might be a good option along the roof-line can add some structural integrity in hurricane-prone/high-wind areas. However, closed-cell spray foam makes the most sense for basement and crawlspace encapsulations because it creates a moisture barrier that can keep that damp, musty air from infiltrating into the conditioned space of your home.

One bonus of spray foaming along the roof (rather than the floor of an attic) is that the attic becomes climate-controlled storage by making that space more comfortable and freeing up your attic floor that will no longer be covered by traditional insulation. It is also shown to prolong the life of your HVAC air handler (if the air handler is in the attic) by preventing exposure to temperature extremes. Deciding whether to spray the attic floor or the roof decking sometimes comes down to budget as the attic floor can be less square footage than the roofline/decking.

On new construction or major renovation projects, we can insulate exterior walls with spray foam or a combination of spray foam and traditional fiberglass batts through a process called “flash and batt.” For existing homes, spraying the attic and crawlspace/basement makes a visible difference and leads to greater comfort and efficiency without insulating in walls. Insulating walls on existing homes is a bit invasive, so we can help clients avoid this by concentrating on the top and bottom of the thermal boundary of the conditioned space.

Yes! Some people can be susceptible to the fumes that come from the installation process. This process is known as off-gassing, which is why we recommend that occupants vacate the home once the spraying has begun and for a period of 12-24 hours after it ends. This will allow for the foam to fully off-gas, and afterwards the home will be completely safe to live in.

Several factors determine price, obviously, but for the most straightforward answer, spray foam is about twice as expensive as traditional fiberglass insulation. Of course, the size of the job, the type of foam being installed, whether or not we need to extract existing insulation, and the fact that some municipalities require the addition of ignition barriers all determine the cost of a spray foam job. However, what you get with that added cost is a high-quality product that outperforms traditional insulation because it is an air barrier and insulator in one.

Yes, spray foam will save you money on your power bills. The length of time it takes for payback is a more challenging question to answer. That depends on how you live in the home and use your HVAC system, etc. Our clients report savings between 15-30% on energy bills with a spray foamed house versus existing traditional homes with fiberglass insulation (and generally do not have proper air sealing).

If shielded from direct sunlight, spray foam should last the lifetime of the structure. It does not break down, so it lasts indefinitely.

If the chemicals are correctly mixed within the recommended temperature range, applied correctly, and allowed time to off-gas, there should be no problems with spray foam. Unfortunately, sometimes the product is not installed properly, and improper installation can cause moisture issues, comfort issues, and financial strain (if it is not providing the intended energy savings).