The Best Expanding Foams, Vetted

Insulate the attic, create an attractive water feature, or prevent noisy pipes, all with the help of expanding foam.

Best Overall

The Best Expanding Foam Option: Great Stuff Smart Dispenser Gaps & Cracks

Great Stuff Smart Dispenser Gaps u0026amp; Cracks

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Runner-Up

The Best Expanding Foam Option: DAP Touch 'n Foam Max Fill Triple Expanding Sealant

DAP Touch u0026#039;n Foam Max Fill Triple Expanding Sealant

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Best Bang For The Buck

The Best Expanding Foam Option: Great Stuff 12-Ounce 8-Pack Big Gap Filler

Great Stuff 12-Ounce 8-Pack Big Gap Filler

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Expanding foam is a flexible product with a wide range of applications, including waterproofing, fireproofing, and insulating, to reduce the flow of heat into and out of the house. It can also be used for blocking sounds, securing water pipes so they don’t rattle in the wooden frame, sealing cracks and gaps around windows, doors, and more.

The versatility of expanding foam makes it simple to choose a general-purpose product for a variety of applications. However, for more specific uses, like building a pond in the backyard or preventing rodents from entering a home, the expanding foam should be made and tested with waterproofing or rodent blocking in mind.

The list of products below is a great place to start the search for the best expanding foam for a home. We examined top-selling products on the market, comparing the features—and, equally important, customer reviews—to come up with our list of favorites. We researched top-rated expanding foam in a variety of categories, focusing on customer satisfaction, product efficacy, and value.

  1. BEST OVERALL: Great Stuff Smart Dispenser Gaps & Cracks
  2. RUNNER-UP: DAP Touch ‘n Foam Max Fill Triple Expanding Sealant
  3. BEST BANG FOR THE BUCK: Great Stuff 12-Ounce 8-Pack Big Gap Filler
  4. BEST WATERPROOF: Red Devil Foam & Fill Large Gaps & Cracks Sealant
  5. BEST PEST-BLOCKING: Tomcat Rodent Block Expanding Foam Barrier
  6. BEST FIRE-RESISTANT: Great Stuff Smart Dispenser Fireblock
  7. BEST FOR CRAFTS: Smooth-On Foam-iT! Rigid Polyurethane Foam
  8. BEST KIT: Froth-Pak 12 Spray Foam Sealant Kit
  9. BEST FOR LARGE PROJECTS: Loctite Tite Foam Gaps & Cracks Insulating Sealant
A person using the best expanding foam option to seal around an electrical outlet
Photo: amazon.com

How We Chose the Best Expanding Foam

We researched the best expanding foam in a variety of categories and chose options with high customer satisfaction. The list factors in gap-filling potential, compatible material, curing and drying times, and special features included by the top brands.

The top expanding foams fill gaps between 1 and 3 inches wide and adhere to a variety of surfaces including wood, concrete, metal, fiberglass, masonry, and other building materials. The list prioritizes options that cure in 24 hours and dry in 15 minutes. The majority of the top picks can be trimmed, sanded, and painted after curing. Additionally, we focused on options that come with precision applicators to make applying the product easier.

Our Top Picks

Product efficacy and overall value were the main criteria for assembling this list of the best expanding foam products, with a further emphasis on the important shopping considerations mentioned in our reviews.

Best Overall

Great Stuff Smart Dispenser Gaps u0026 Cracks

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This expanding foam from Great Stuff has a drip-free straw dispenser for precision control and application; the flow of the foam is controlled by a trigger on the dispenser, allowing you to stop the flow immediately by releasing the trigger. The low expansion foam adheres to wood, metal, masonry, glass, and most plastics so it can seal gaps, crevices, and cracks inside and outside of the home.

This Great Stuff expanding foam can fill gaps up to 1 inch in width, making it a good choice for installing new windows or doors. The foam dries to the touch in about 15 minutes and can be trimmed in 30 to 60 minutes (it’s fully cured after about 8 hours). After trimming the foam, sand it down and paint or stain it to render it almost unnoticeable.

Product Specs

  • Fills gaps: Up to 1 inch wide
  • Compatible materials: Wood, metal, masonry, glass, and most plastics
  • Curing time: 8 hours
  • Quantity: 12 ounces

Pros

  • Dries to the touch in 15 minutes; fully cures in just 1 hour
  • Can be trimmed, sanded down, painted, or stained depending on users’ needs
  • Includes a drip-free straw dispenser to prevent mess or unwanted application

Cons

  • Some users report clogs in the dispenser; may take some tinkering to prevent this issue

Get the Great Stuff Gaps & Cracks expanding foam at Amazon, Lowe’s, or The Home Depot.

Runner-Up

DAP Touch 'n Foam Max Fill Triple Expanding Sealant

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Apply DAP Touch ‘n Foam Max Fill expanding foam to the inside or outside of the home in order to insulate against drafts and moisture accumulation. The expanding foam is resistant to extreme temperature changes, rain, sleet, and snow but is vulnerable to ultraviolet (UV) radiation, which will discolor the foam. The 12-ounce can of foam comes with a precision straw applicator, making it easy to spray the foam into narrow gaps and crevices.

This fire-resistant expanding foam fills gaps greater than 1 inch in width, creating an airtight, water-resistant seal. It dries in 15 minutes; when it fully cures in 4 hours, it can be sanded, painted, or stained. The low expansion foam repels insects and other pests, protecting the home from infestations.

Product Specs

  • Fills gaps: Over 1 inch wide
  • Compatible materials: Not specified
  • Curing time: 4 hours
  • Quantity: 12 ounces

Pros

  • Can be used indoors and outdoors; withstands extreme temperature changes, rain, and sleet
  • Dries in 15 minutes and fully cures in 4 hours
  • Can be sanded, painted, and stained to accommodate users’ desires
  • Comes with a precision straw applicator for added ease of use

Cons

  • Unknown material compatibility; may not adhere well to some building materials
  • Vulnerable to UV radiation; may crack or warp under intense sun exposure
  • Some report the applicator clogging; may take some tinkering to adjust

Get the DAP Touch ‘n Foam expanding foam at Amazon.

Best Bang For The Buck

Great Stuff 12-Ounce 8-Pack Big Gap Filler

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The Great Stuff Big Gap Filler can fill gaps, cracks, and crevices up to 3 inches thick, making it ideal for fixing holes in walls; creating packing for moving boxes; and sealing water, gas, and electric service penetrations. This inexpensive value pack comes with eight ready-to-use spray cans of expanding foam, making it a great choice for large home renovations or multiple projects.

The low-expansion foam dries to the touch in just 15 minutes and can be trimmed after 1 hour. It adheres to wood, metal, masonry, glass, and most plastics, forming a water-resistant seal once it has cured. The foam takes about 12 hours to fully cure, at which point it can be sanded, painted, or stained.

Product Specs

  • Fills gaps: Up to 3 inches thick
  • Compatible materials: Wood, metal, masonry, glass, and plastics
  • Curing time: 12 hours
  • Quantity: 12 ounces (pack of 8)

Pros

  • Dries to the touch in 15 minutes and fully cures for trimming in 1 hour
  • Can be sanded, painted, or stained depending on users’ needs
  • Includes a straw applicator for precise application on wood, metal, masonry, glass, and most plastics

Cons

  • Some report that the cans did not dispense the foam

Get the Great Stuff Big Gap expanding foam at Amazon or The Home Depot (single can).

Best Waterproof

Red Devil Foam u0026 Fill Large Gaps u0026 Cracks Sealant

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This expanding foam is best used to waterproof the home against the elements. It comes in a ready-to-use can and has a precision-applicator straw that makes it easy to fill cracks and crevices in the foundation from the inside of the home or the outside. The barrier created by the foam becomes waterproof and airtight after it has fully cured, helping to seal out moisture.

The low-expansion foam can be applied to painted or unpainted wood, concrete, cinder blocks, aluminum, fiberglass, and masonry materials like brick and mortar. It can also be used to seal windows and doors as well as any service penetrations for water, gas, or electricity. It takes between 4 and 24 hours to fully cure; after this period of time, it can be sanded, painted, or stained.

Product Specs

  • Fills gaps: Not specified
  • Compatible materials: Wood, concrete, cinder blocks, aluminum, fiberglass, and masonry
  • Curing time: 4 to 24 hours
  • Quantity: 8 ounces

Pros

  • Waterproof formula can be used for indoor and outdoor applications
  • Can be sanded, painted, or stained depending on a given user’s needs
  • Includes a precision applicator for added user-friendliness and reach while applying

Cons

  • Some complaints that the process is messy; may require gloves and tarping

Get the Red Devil expanding foam at Amazon.

Best Pest-Blocking

Tomcat Rodent Block Expanding Foam Barrier

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Expanding foam is great for preventing water damage and sealing drafty windows and doors, but many products are susceptible to rodent nibbling. Tomcat Rodent Block expanding foam barrier is specifically made to handle mice, rats, and other pests with a dense, bitter-tasting formula that not only seals but also repels mice (instead of it becoming a snack).

The low-expansion foam comes in a 12-ounce spray can and has an applicator straw so it can be precisely controlled and applied to narrow cracks and crevices. It forms an airtight and water-resistant bond with most building materials, allowing it to be used indoors or out. Once the expanding foam has fully cured, it can be trimmed, sanded, or painted to get a finished appearance.

Product Specs

  • Fills gaps: Not specified
  • Compatible materials: Most building materials
  • Curing time: Not specified
  • Quantity: 12 ounces

Pros

  • Can be used for indoor and outdoor applications; water-resistant formula
  • Specially formulated to repel mice; bitter-tasting foam keeps all pests away
  • Can be trimmed, sanded, and painted depending on users’ needs

Cons

  • Unknown gap filling and curing time; may not be suitable for some users’ needs
  • Some reports that mice chew through the foam; may need more than 1 application for bad infestations

Get the Tomcat expanding foam at Amazon, Lowe’s, or The Home Depot (2-pack).

Best Fire-Resistant

Great Stuff Smart Dispenser Fireblock

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Use this low-expansion foam to secure electrical wires and in areas that pose a fire risk, like around outlet boxes. The fire-resistant formula is made to seal service penetrations in the framework of the home so fire and smoke cannot move freely through these gaps. The simple act of blocking off the gaps can prevent a house fire from destroying the entire home. This expanding foam sealant can also create an airtight, water-resistant seal for acoustic and thermal insulation.

Its bright orange color makes this expanding foam easy to identify, and it adheres to most building materials, sealing and insulating gaps up to 1 inch in size. It comes with a long straw dispenser for better control and precise application. It dries to the touch in just 15 minutes; however, it takes a full hour until it can be trimmed or sanded.

Product Specs

  • Fills gaps: Up to 1 inch wide
  • Compatible materials: Wood, metal, masonry, glass, and most plastics
  • Curing time: 8 hours
  • Quantity: 12 ounces

Pros

  • Fire-resistant formula; fire and smoke cannot move freely through the foam
  • Dries to the touch in 15 minutes and cures for sanding or trimming in 1 hour
  • Comes with a precision applicator for user-friendliness and hard-to-reach places

Cons

  • Some reports of messy process; may require tarping and gloves while applying

Get the Great Stuff Fireblock expanding foam at Amazon, Lowe’s, or The Home Depot.

Best for Crafts

Smooth-On Foam-iT! Rigid Polyurethane Foam

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Sealants can help with crafts like prop making, castings, or filling in little gaps. For these projects, we recommend the Smooth-On Foam-iT! polyurethane foam. This foam sealant has a 5-pound-per-foot density and expands to 10 times its original size.

Its two-component castable rigid urethane foam is perfect for light to medium-size crafting tasks. It cures to a tack-free consistency in 4 to 6.5 minutes and fully cures in 2 hours. To use, simply mix the two canisters with a 1:1 ratio and apply. The only downside to this option is that it has a very short shelf life and must be used soon after purchase.

Product Specs

  • Fills gaps: Not specified
  • Compatible materials: Most materials
  • Curing time: 2 hours
  • Quantity: 1.9 pounds or 15 pounds

Pros

  • Perfect for small to medium-size casting, set building, and prop-making crafts
  • Easy to use; simply mix the 2 canisters with a 1:1 ratio and apply
  • 5-pound-per-foot density; expands to 10 times its original size
  • Cures to a tack-free consistency in just 4 to 6.5 minutes

Cons

  • Very short shelf life compared to similar options; should be used shortly after purchase

Get the Smooth-On expanding foam at Amazon.

Best Kit

Froth-Pak 12 Spray Foam Sealant Kit

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Made for professional or DIY use, the Froth-Pak 12 spray foam sealant kit can be used for a variety of repair or insulation tasks. Durable and waterproof, this sealant comes with a two-component polyurethane spray foam system with an Iso and Polyol can, an application gun with a thumb-controlled spray dispenser, two 3-foot hoses, three interchangeable and precise applicator tips, and a can carrier and strap for using in living spaces, outdoors, attics, and more.

The Froth-Pak kit is ideal for insulation while blocking out any unwanted airflow, moisture, dust, noise, and pests and can be used for duct work, pipes, electrical work, plumbing, and mechanical applications. Plus, this foam sealant can be used on wood, masonry, metal, drywall, stone, and more for added versatility.

Product Specs

  • Fills gaps: 12 square feet
  • Compatible materials: Wood, masonry, metal, drywall, stone, and more
  • Curing time: 1 minute
  • Quantity: 3 pounds

Pros

  • Comes with a dual tank spray foam system, thumb-controlled spray dispenser, hoses, 3 applicator tips, and a carrier
  • Can block out airflow, moisture, dust, noise, and pests while providing insulation
  • Suitable for duct work, pipes, electrical work, plumbing, and mechanical applications

Cons

  • Additional Iso and Polyol cans may need to be purchased for larger projects

Get the Froth-Pak expanding spray foam at Amazon.

Best For Large Projects

Loctite Tite Foam Gaps u0026 Cracks Insulating Sealant

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Large projects that require a lot of durability from expanding foams can rely on the Loctite insulating sealant. This insulating pick expands to fill gaps and cracks up to 1 inch in size and comes with enough quantity per can to tackle large-scale tasks. This long-lasting polymer foam is made with purified and concentrated ingredients that can withstand harsh UV exposure, making it suitable for outdoor use. Simply spray on with the built-in applicator and wait 24 hours for the full curing to take effect.

Made with a uniform cell structure, this foam can be used on plumbing, wiring, HVAC and ductwork, basements, attics, and more as it can adhere well to most building materials, including wood, metal, stone, and brick. Finally, this foam is flexible enough to withstand building and material movement after application.

Product Specs

  • Fills gaps: Up to 1 inch
  • Compatible materials: Wood, concrete, metal, stone, PVC, brick, and more
  • Curing time: 24 hours
  • Quantity: 12 ounces

Pros

  • Long-lasting polymer foam; purified and concentrated chemicals and ingredients can withstand harsh UV exposure
  • Suitable for both indoor and outdoor use; can be applied in attics, backyards, garages, and more
  • Safe for wiring, plumbing, HVAC and ductwork, and more
  • Built-in applicator allows for ease of use and precision while applying

Cons

  • May be difficult for first timers to use; has a bit of a learning curve

Get the Loctite expanding foam at Amazon or The Home Depot.

Jump to Our Top Picks

What to Consider When Choosing an Expanding Foam

When shopping for an expanding foam for sealing cracks and gaps around windows, insulating moving boxes, or securing wires or plumbing, factor in the expansion size, the functionality of the specific product, and whether it’s applied with a spray can or a handheld gun.

High vs. Low Expansion 

Expanding foam products fall into two broad categories based on the amount that they can expand beyond the liquid size.

  • High-expansion foam is typically used in commercial and industrial settings for quickly filling large gaps and cracks in doorways and windows. It is also regularly used for filling holes in the foundation and mortar where water, gas, and electrical lines have been run. This type of expanding foam can expand up to 200 to 300 times its liquid size. It can include open-cell foam, which can allow moisture to flow through the foam, and closed-cell foam, which completely blocks moisture and airflow.
  • Low-expansion foam, in contrast, can only expand up to 20 to 30 times its liquid size. This smaller size makes low-expansion foam a great choice for home repairs because the gaps, cracks, and utility holes are generally much smaller. High-expansion foam would quickly seep out, creating a dripping mess, while the low-expansion foam is much easier to manage.

Functionality

Most people use expanding foam for its versatile formulas, including waterproofing, fireproofing, acoustic insulating, and thermal insulating.

  • Waterproofing with expanding foam is a common usage around the home. Sealing cracks and gaps in the foundation, walls, and around windows and doors helps prevent water from leaking into the home. Some expanding foam products can even be used to help create ponds, fountains, and other water features for the yard.
  • Fireproofing the home is very important, and some expanding foam products, designed to be highly fire-resistant, can be used for this purpose. The foam can seal holes between floors where wires and pipes run and can be used to seal gaps around wall outlet boxes to prevent loosening, while at the same time serving as a fire barrier should disaster strike.
  • Acoustic insulating helps prevent the transfer of noise between rooms, floors, and exterior walls. High-expansion foam can be used to insulate a wall, floor, or ceiling, while low-expansion foam is used for sealing cracks and gaps where ductwork, plumbing, and electrical run through the home so sound cannot pass through these holes.
  • Thermal insulating is often done with high-expansion foam because it can be used to quickly insulate an entire room. However, sealing up cracks around window and door frames with low-expansion foam is also important to ensure that the home is properly insulated.

Application

Expanding foam products will typically come prepared for use in a spray can or in separate components that need to be applied with a handheld gun.

  • Spray cans are easy to use. The can comes premixed so there is no wait time before the expanding foam can be applied. These products may also come with a long, narrow dispenser that connects to the nozzle, allowing the foam to be injected into very small gaps with precise accuracy. However, only low-expansion foam comes in a spray-can format.
  • Handheld guns take more knowledge and experience to use with precision but are the best option for large projects like insulating the attic. These products typically include two separated components in pressurized tanks. The handheld gun has two hoses and connects to both tanks. When the user is ready, the tank valves are opened, allowing the expanding foam to be sprayed through the nozzle of the gun. This type of application is usually only used with high-expansion foam.

Tips for Using Expanding Foam

Simply put, expanding foam expands. That may seem like an obvious statement, but it’s something that can be all too easy to forget while spraying the foam into a deep cavity or recess. If the foam is sprayed too quickly, the crevice or gap can overflow, leaving a dripping mess that must be removed with a utility knife after it dries.

Similarly, any accidental spills or sprays on nearby walls should be cleaned up after the expanding foam dries. Trying to clean up an expanding liquid inevitably creates a larger mess that is more difficult to remove. When the foam sets, it can usually be scraped from a nonporous surface, though wood and other porous materials may need to be refinished.

Always inspect the area where the insulation will be applied before installation. Older homes and homes with wooden shingles may be built with a design that allows the natural evaporation of excess moisture. Insulation installed in these areas acts as a sponge, soaking up the moisture instead of allowing it to dissipate. As moisture builds up, mold can grow and eventually rot out the wood.

  • Take time to slowly install the foam to avoid overflow.
  • Don’t try to wipe up spills and mistakes; wait until the foam has dried to scrape it off.
  • Carefully inspect older homes before installing insulation to ensure it won’t cause moisture accumulation, which can lead to mold and rot.

FAQs

Expanding foam products are designed to seal cracks and gaps, secure plumbing and wiring, and block rodents and other pests from entering the home. Take a look below to find the answers to some of the most commonly asked questions about how to use expanding foam and the dangers it can pose.

Q. Which expanding foam expands the most?

High-expansion foam expands the most. It’s capable of expanding 200 to 300 times the liquid size, while low-expansion foam can only expand up to 30 times its liquid size. However, most common expanding foams on the market will cover cracks or gaps of 1 to 3 inches, with some options coming with enough quantity to cover 12 square feet of space.

Q. Is there a waterproof expanding foam?

Yes, some expanding foam is designed to be waterproof. Certain products are even made specifically for building ponds, fountains, and other outdoor water features. For added convenience, those waterproof expanding foams are also made to withstand harmful UV rays to ensure maximum longevity and durability.

Q. Where should you not use an expanding foam?

Expanding foam isn’t a good idea for every area of the house. Avoid spraying expanding foam too close to electrical boxes or light boxes where the foam can pose a fire hazard, unless it is specifically designed for this purpose. Also avoid using open-cell spray foam on the roof because it can cause moisture to accumulate, rotting out the roofing. If you aren’t sure whether to use expanding foam for a specific problem or in a specific area, check with the manufacturer before using it.

Q. What are the dangers of expanding foam?

Expanding foam needs to be applied with proper ventilation and breathing protection because the chemicals produced by the spray foam vapor can trigger asthma, eye irritation, itching, and rashes. If proper protection is not worn, irritation and even allergic reactions can occur.

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Timothy Dale

Contributing Writer

Timothy Dale is a home improvement writer who has been in the industry for several years. In his work for BobVila.com, he has written a number of how-to articles related to yard maintenance, vehicle repair, and home renovation, not to mention a wide variety of buying guides and articles on DIY projects. He always ensures readers get the information they need to tackle their next project.

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