Use these tips to help ensure you’re hiring the best professional for your spray foam insulation project:

• Licensing: Choose a pro who is licensed, bonded and insured in your state 

• Certification: Find a pro who has certifications or accreditation from organizations like IDI Distributors or the Spray Polyurethane Foam Association. 

• Specialization in spray foam insulation: General insulation companies may not have as much experience with spray foam as someone who does it every day. 

• References and reviews: If you want to verify a pro’s experience and professionalism, read their customer reviews and ask for a client reference.  

• Quotes: Always aim to get quotes from several pros so you can compare prices and avoid getting overcharged for services. 

• Warranties: Try to choose a pro who has a warranty that covers workmanship, materials and performance standards. If the insulation fails, a warranty can cover the cost of repairs or replacement. Remember to read the fine print and make sure you understand the warranty’s conditions. 

For more tips, visit our Smart Hiring guide.

Installing spray foam insulation costs an average of approximately $1,190 to $3,230*, according to Thumbtack data. Some of the most common cost factors to consider include:

• Home layout and size: Contractors will usually charge more to insulate hard-to-reach areas and multiple rooms.

• Insulation thickness: An insulation contractor will be able to advise you on how much insulation you need. The more you need, the more you can expect to pay.

• Open- vs. closed-cell foam: Open-cell insulation usually costs less than closed-cell, according to the Department of Energy. Closed-cell foam has high-density cells that are filled with gas to help the foam expand, which protects against moisture and air leakage. Open-cell foam cells are filled with air, giving the foam a spongier texture.

*Data on file at Thumbtack. For a personalized cost estimate, request a quote from a professional.

Spray foam insulation is a liquid foam that expands after installers spray it onto a surface, forming an airtight layer of insulation. There are several benefits to spray foam insulation that make it worth the cost when compared to other types of insulation:

• Energy efficiency: Closed-cell spray foam insulation has a higher R-value (resistance to heat transfer) than other types of insulation. 

• Ideal for tight spaces: Unlike foam board and batt and roll insulation, spray foam is a liquid, allowing it to fill irregular and narrow spaces with ease.

• Seals out moisture and air: Spray foam forms a tight bond with the wall or ceiling underneath, keeping air and moisture out — and improving indoor air quality.

Spray foam insulation works in most areas of your home, such as:

• Attics

• Basements

• Crawlspaces

• Wall cavities

• Roofs

• Floors

It's also ideal for small openings or awkward areas. For example, you can reduce drafts by using spray foam around electrical outlets, ductwork or pipes where they enter or exit walls. It's also useful for sealing gaps in window and door frames.

However, avoid using spray foam where it could pose a fire hazard or trap moisture. While you can use spray foam around the outside of electrical boxes or conduits, you should not use it anywhere it could come into contact with the wiring. Spray foam should also not be used near fireplaces, wood-burning stoves or chimneys. 

You can use spray foam to seal around a pipe that runs through an exterior wall, but avoid using this type of insulation to cover long spans of pipe running through walls or ceilings — particularly if they're prone to sweating. Here, it's best to use a more breathable insulator that will allow moisture to evaporate.

When in doubt, consult a pro to help you decide where to add spray foam insulation.

Spray foam insulation comes in two varieties: closed cell and open cell.

Closed-cell spray foam expands slower, has a higher R-value, doesn’t require a vapor barrier and won’t become waterlogged. It’s ideal for exterior wall cavities, attics, areas with high humidity or anywhere there’s a risk of water exposure. However, it tends to be more expensive than open-cell spray foam. 

Open-cell spray foam expands faster, has a lower R-value, may require a vapor barrier and can become soggy and ineffective if it gets wet. It has better soundproofing qualities compared to closed cell spray foam, so it’s a good choice for interior wall cavities. Its fast expansion rate also allows it to effectively seal gaps in areas that are difficult to reach.

Still not sure which one to get? A pro can inspect your home and help you decide which one is right for you.

Applying spray foam insulation involves injecting a liquid mixture into wall cavities, creating an air-tight seal. Here's what the project typically entails:

• Evaluation and planning: Before application, your pro will likely investigate the space for any damage or moisture risks that could limit adhesion. Surfaces are meticulously covered to avoid overspray, and ventilation systems may be installed to improve air quality during application.

• Controlled application: Liquid components are usually mixed onsite and applied in measured passes using high-pressure spray equipment. Pros often monitor expansion rates to reduce the risk of voids or uneven layers, especially in hard-to-reach areas like vaulted ceilings or crawl spaces.

• Curing and inspection: The foam expands and sets quickly, but pros allow adequate curing time before testing insulation performance with thermal cameras or airflow meters.

• Finishing touches: Excess foam is trimmed, and edges are sealed to seamlessly integrate the insulation with structural elements.

Before hiring, talk to a spray foam insulation contractor near you about their experience with complex installations and their moisture mitigation strategies.

The time it takes for a professional to apply spray foam insulation depends on the size of the area being sprayed, the type of spray foam used and the amount of prep work required. Generally, a 1,000-square-foot surface could take anywhere from a few hours to a full day, including set prep and cleanup. 

Keep in mind that closed-cell spray foam typically takes longer to apply than open-cell spray foam because it’s more dense and expands slowly, requiring more precise application. It also needs to be applied in thin layers, so a second pass may be necessary to achieve the correct R-value. 

Because there are several variables at play, it’s best to contact a pro for a project timeline. 

Remember: The timeline for your project will vary depending on many factors. Always ask your pro to provide an estimate.