Spray Foam Insulation FAQs

Spray Foam FAQs

Spray Foam insulation typically costs 2 to 3 times more than traditional Fiberglass Insulation.  Open Cell Foam ranges from $1.50 to $5.00 per square foot, while Closed Cell Foam Insulation ranges anywhere from $2.30 – $7.20 per square foot.  Prices vary based upon the depth of the foam being applied.  To get the exact cost for your spray foam insulation project, request a free estimate.

Both Open Cell and Closed Cell Spray Foam are air impermeable at certain thicknesses and can qualify as an air-barrier material. Closed Cell Foams are also water-resistant. Closed Cell Foam is the only spray foam that can be used where contact with water is likely (e.g., below-grade concrete walls, foundation walls from the outside and in contact with the ground, or on the exterior side of the building envelope above grade and under an exterior finish). 

Open-cell spray foam has an open-cell structure, hence the name where the cells are filled with air. The open-cell structure is a soft, flexible foam. It has a density of about 0.5-0.75 pounds per cubic foot. The open-cell foam is soft and therefore must be protected from damage as it is not a “memory” foam.  It will move as the framing of the home moves from winter to summer and back again up to one inch in each direction and back. The R-value per inch of open-cell foam typically ranges from R3.6 to R4.5 per inch. Open-cell foam does not work as a vapor barrier! It will allow bulk moisture to move through it.

Closed-cell spray foam has a closed-cell structure which is rigid, hard foam, with a density of 1-2 pounds per cubic foot. (Specialty closed-cell foams range up to a density of 10lbs per cubic foot) and has been demonstrated to provide a structural enhancement in certain framed buildings of as much as 200%. These smaller cells trap an insulating gas, called a blowing agent. This blowing agent has a lower thermal conductivity than still air and increases the R-value. Typical R-value per inch of closed-cell foam ranges from R-5 to R-7.4 per inch, making it a great choice in applications where framing depth is limited.  Closed-cell foam is the foam of choice on masonry construction or below grade where bulk moisture is present. Closed-cell foam is often used in crawl spaces, wine room/ cellars and even occasionally on the bottom of a bathtub to maintain water temperature during usage.

Spray Foam Insulation, sprayed to the appropriate depth of not less than 1.5 inches and typically 2 inches or more is an air-barrier. Spray foam insulation qualifies it as an air-barrier material, dramatically reducing air leakage through the building envelope. As a result, it significantly lowers the building’s heating and cooling costs.  Cellulose insulation, in certain situations, is a great option to reduce air leakage and do a “better” job of maintaining comfort in the home/ business. Fiberglass insulation is the lowest quality option of the three as it is both poor insulation and not an air barrier at any depth. Fiberglass insulations are best utilized as an inexpensive option for sound insulation and are easy to self-install.

Spray Foam insulation is made from Polyurethane. Properly installed spray foam should not need to be replaced.  Manufacturers’ warranty foam for the life of the structure!

No!  For most applications, when using spray foam insulation you do not need to use 2×6 construction to meet code. If you reach out to us during the design phase of your project we can help you determine the answer to this question based on the location of your project. 

In certain installations, the foam and mechanical package can reduce costs over a similar home with standard insulation (code) by as much as 90%!

If you are having condensation problems, spray foam insulation can help. Condensation forms when moist air inside comes into contact with a cold surface. Foam insulation creates an air seal reducing the demands for dehumidification by the HVAC equipment but relying on the proper venting of the bathrooms to the outside.  Spray foam homes without proper bathroom ventilation and mechanical adjustments can be very difficult to de-humidify and control condensation. Homes with steam showers, saunas, and indoor pools require significant mechanical dehumidification and air control, Closed-cell spray foam is outstanding to control these issues!

There are many reputable brands of foam insulation on the market. If you are buying a “top shelf” foam, you are buying from a contractor who is paying a premium for the product and is certified by the manufacturer. Ask to see the credentials of the contractor.  Call the manufacturers representative and ask who their favorite/ most trusted applicators are in the area. This info will tell you lots about the organization you are thinking of buying from.

The key to understanding the quality of foam an installer is providing is to ask for ESR Documentation. If ESR documentation is not available it is not worth the risk. You do not want foam insulation that cannot be backed by an ESR Document and manufacture who has certified the contractor is a safe installer. 


The answer depends on what you are doing, what your expectations are and where the foam is going.  The short answer is, you need just enough to accomplish your goals and nothing more. More is not better!

Our Recommendation…. reach out to us during the design or conversation stage so we can determine the answer and help you get the project moving.

One inch of foam on the interior is not enough for much of anything.  Often I find that contractors in Chicago offer 1 inch as an “air barrier/ seal” and that is not true.  1 inch of foam to the exterior of the framing is the gold standard!

Open-cell foams do allow water to move through it when submerged and are not appropriate for wet areas of construction including below-grade and masonry construction.  Closed-cell foam is resistant to water absorption at depths determined by the density of the material. A single inch of any closed-cell foam IS NOT A VAPOR BARRIER no matter what your other guys have told you!  Vapor barriers with closed-cell foam vary from 1.4” to 2”! Closed-cell foams are approved by FEMA as a flood-resistant material! It is important to consider the different properties for each foam type for each application.

Spray foam insulation, like most site-applied building materials, will release small amounts of chemical compounds into the air and is not safe for unprotected individuals to be onsite during the install!  Re-occupancy after completion of the application is typically 24 hours from the time we complete the installation of the foam. Spray foam can give off odors that may be noticeable by some people, but with proper ventilation, these odors will subside when the foam is properly mixed and cured.  Detailed information can be provided on a per-project basis. It is critical to understand that foam insulation is plastic and will have some smell.  

Yes, when we come to your project we are bringing either two or four drums of foam, one or two sets.  We will actually “manufacture” the spray foam on-site during the application taking these two materials iso and resin and mixing them in a 1:1 ration. 

The foam products we use have a Class A, Type 1 fire rating.  Every situation is different and we can discuss this with you in detail at the estimate.  In general, all-foam must be separated from living space with a fire-rated material. We take great care during the install and at the inspection to make sure our products are installed to code and pass local inspection! Third-party inspections are welcome on all of our projects.

Before hiring a spray foam contractor, always be sure that the applicator on the job site is properly trained. At a minimum, the applicator should have completed a two or three-day equipment and materials course provided by the material supplier or distributor.  Look for the affiliations of the organization, industry memberships and involvement in the local community. We will happily provide lots of references for our work to anyone who asks!

Yes, spray foam is an ideal product for insulating and air-sealing existing homes in areas that are either unfinished or under construction.  Spray foam can be used to create energy-saving unvented attics and crawlspaces that seal against air leakage and bring under-insulated and leaky HVAC ducts inside the conditioned space of the building. Also, spray foam can be used to insulate and air-seal band and rim joist areas where the framing meets the home’s foundation.

Yes, during and immediately following spray foam applications, fumes and mists are generated that can be hazardous to your health. Access to the work area during this time should be restricted to personnel wearing appropriate personal protective equipment (PPE), including respirators, and whose job responsibilities require them to be in the area.

The application of spray foam can produce hazardous levels of airborne chemicals during and just after installation. These chemicals, most notably MDI, will degrade into non-hazardous compounds in a few hours when combined with moisture in the air. Because of these short-term airborne levels, re-occupancy of the work area by other trades or building occupants is typically 24 hours.

Only as approved by ESR report: http://tiny.cc/pouuiz Any sub-contractor offering this system without the proper documentation is not following best practices in our industry.  Adding other insulation to spray foam voids the spray foam manufactures warranty! The foam and the other material must be made by the same manufacturer to be tested and deemed as safe as applied!

Yes, Chicago adopted the 2018 IECC in October of 2019.  Chicago still has a long way to go but, until recently no insulation inspections were done in Chicago and that made it tough for us as we do installs by the book and to code regardless of inspections!

Yes, the surrounding Chicago Villages do permit Spray Foam Insulation. Lincolnwood was the last hold out to my knowledge in the Chicagoland area and I was the first contractor to install spray foam in the village of Lincolnwood.  Winnetka was a “holdout” for many years or you had to be on a special list maintained by the inspector Rudy who has long since retired. Happy to talk about Rudy, if you ever want to hear those stories!  

No, but that does not mean that mold cannot grow on the surface of the plastic spray foam insulation. Building materials, when installed to create a building envelope assembly, work interactively as a system, to control the movement of heat, air, and moisture. 

When not properly designed or installed, moisture can move through the building envelope and condense on cold surfaces that are below the dew point temperature or create high levels of moisture. This moisture, at certain temperatures, in the presence of organic food sources (paper, wood, bacterial dust, etc.) can provide the conditions necessary to promote the growth of mold and mildew. While Spray Foam is not a source of food for mold, mildew or bacteria, organic specks of dust can collect on the surface of the foam. In combination with moisture at the right temperatures, these organic specks of dust can result in mold and mildew.  Spray Foam, like all insulation products, can result in mold and mildew problems in building envelopes that are poorly designed or constructed. Proper air sealing, as well as use and placement of vapor retarders and sufficient levels of insulation, are key to proper building envelope design.

The chemical reaction used to create polyurethane and polyurethane foams give off heat, which is called an exothermic reaction. Closed-cell Spray Foam products, when installed at pass thicknesses exceeding manufacturer’s recommendations, can generate excessive heat that can be trapped inside the foam. This heat can result in poorly formed foams that dramatically reduce coverage rates and diminish product performance, causing loss of R-value or shrinkage. In extreme cases, where closed-cell foam is applied at thicknesses several times the manufacturer’s limits, can generate enough heat to self-ignite the foam. The Spray Foam contractor should always follow the manufacturer’s installation instructions regarding pass thickness and times between passes to eliminate damage caused by exothermic reactions.

Problems with spray foam installation should be resolved between the building owner (customer) and spray foam contractor that installed the foam. If these issues cannot be resolved at this level, the building owner should contact the supplier of the foam.  Below is a list of typical installation and service problems.

Some spray foam materials may give off a noticeable odor for several days after application. These odors, noticed by some people, are usually caused by unreacted amine catalysts and have been described as smelling like fish, cat urine or fresh latex paint. If these smells are due to unreacted chemicals, they will not go away with time.  Further investigation, analysis by the manufacturer reps and other third party professionals should be involved. Some odor will be present after the foam is installed. This odor is not indicative of a chemical hazard but can be a general nuisance, think new plastic, carpet or furniture being purchased and brought into the house. Supplementary ventilation of the work area for a few days is recommended to reduce these odors. If other odors are present or persistent, or the foam is discolored or inherently sticky, or friable, these are symptoms of improperly installed foam.

When improperly applied, some spray foam, particularly closed-cell foam, products may shrink and pull away from structural framing and exterior walls/ roof. Improper equipment settings, excessive pass thicknesses, and old/ expired material can result in foam shrinkage. While isolated amounts of shrinkage can occur, the number and size should not be extensive. Cracks and gaps caused by shrinkage can compromise the air sealing performance of the insulation and could result in moisture condensation problems in colder climates. Extensive shrinkage should be repaired.

Much like paint, spray foam should strongly stick to nearly all construction materials that are clean, dry and free of oils and grease. Substrates must be free of oil, dust, dirt, and moisture, and applied according to manufacturer’s instructions, there should be no problems with adhesion. Adhesion should be occasionally checked by tearing a small area of foam from the substrate. When properly adhered to, the foam itself should tear, leaving a thin but visible residue of foam on the substrate. However, spray foam may not adhere well to some construction materials, such as polyethylene sheeting, under-cured concrete (containing excessive moisture or surface contaminants) and certain metals. These materials may need special surface treatments, such as primers or coatings before Spray Foam can be applied.

Spray foam applications, especially high-pressure foams, will leave a coating of fine droplets on all surfaces near the work area. Depending on the surface material, these fine droplets may not be easily removed. It is very difficult and may not be possible to completely remove Spray Foam overspray and residue from most porous surfaces. On smooth surfaces, Spray Foam overspray may be mechanically removed using buffing and polishing compounds.  Spray Foam cannot be dissolved using most common solvents. All finished surfaces, and especially smooth surfaces such as glass, porcelain, and metal, should be thoroughly masked before application.

About the Author, Tom Decker

With ten years of experience selling spray foam insulation in Chicago, Tom Decker is THE person to call and the Chicago Green Insulation is the organization to hire when you are looking for top notch quality and performance as well as someone who can deal with the needs of code officials, home owners and general contractors. Call the others in Chicago, if you are interested in the cheapest price, call Chicago Green Insulation if you are interested in using your dollars to make Chicago a better city for all of us!

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