Cures flexible
Once cured, Flex Foam remains flexible, moving with your home as gaps shift. That flexibility helps resist cracking and crumbling, maintaining the seal over time.
- Finish
- Bright white
- Once Cured
- Cut, Sand, Paint, or Stain
- Cures in
- 8 –12 Hours
- Holds from
- −40°F to 176°F
A seal that moves with
your home
A window joint is rarely one size for long. One-component expandable polyurethane fills it, then goes on flexing with it.
As temperatures rise and fall, building materials expand and contract, allowing the gaps around them to widen or narrow. Flex Foam stays flexible through those changes, helping the seal resist cracking or breaking apart.
As your home settles, framing can shift, and gaps can change shape. Flex Foam flexes with that movement to help keep the gap sealed.
Doors slam. Trucks pass. The HVAC kicks on. Flex Foam helps reduce noise and flexes with those repeated movements to help maintain the seal.
- Joint width
- 3⁄8″ to 3⁄4″
Controlled expansion
Flex Foam’s low-pressure formula expands just the right amount to fill gaps without putting excess pressure on window and door frames, helping prevent bowing or warping.
Flexibility is just the beginning
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Seals and insulates
Flex Foam fills and insulates gaps to help block drafts and moisture; no backer rod or separate insulation needed.
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Water and weather resistant
Forms a flexible, water-resistant barrier that helps maintain the seal through freezing cold and attic heat, indoors or out, from -40°F to 176°F (once cured).
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Bright white finish
Cures bright white and can be cut, sanded, painted or stained for a clean, professional look.
It fills.
Then it flexes.
It expands to fill the gap, cures flexible, and holds up to what the joint does afterwards.
Regular foam cracks.
This one doesn’t.
Cured Flex Foam moves with the joint instead of fighting it, so it stays whole through the seasons a rigid sealant splits in.
Fill it
Expands to fill gaps without putting excess pressure on window and door frames.
Bend it
Stays flexible as it bends.
Twist it
Resists cracking or breaking when twisted.
Where To Use Flex Foam
Select an area below to see common places where Flex Foam can seal and insulate gaps around your home.
Bring home Flex Foam.
A super flexible, expandable foam sealant that fills gaps and helps keep them sealed as they shift, expand, and contract. Once cured, it can be cut, sanded, and painted for a clean, finished look.
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Secure checkout
Flex Foam12 oz.
Color Bright white
$9.99 per can
Product details
Flex Foam™ super flexible expandable foam sealant
Fills, seals & flexes!
An easy-to-use expanding foam sealant that fills gaps and holes while creating a durable, water-resistant barrier that helps block moisture, drafts, pests, and noise. It also insulates to help save on energy bills. Flex Foam cures into a strong, flexible, rubber-like structure that moves with shifting surfaces to resist cracking and breaking. Once cured, the bright white foam can be trimmed, sanded, painted, or stained for a clean, professional finish.
- Expanding formula – fills gaps and holes for a tight seal.
- Water-resistant barrier – helps block moisture, drafts, pests, and noise.
- Insulates – helps save on energy bills.
- Super flexible – cures into a rubber-like structure that moves with shifting surfaces to resist cracking and breaking.
- Bright white finish – trim, sand, paint, or stain for a clean, professional look.
- Easy to use – seal gaps and holes around the home with no hassle.
Excellent for: plumbing, HVAC, spigot, and other penetrations, window and door frames, attic hatches, basement and crawlspace gaps and penetrations, brick and concrete gaps, siding gaps and holes, soffits and fascia, pipe insulation, pest prevention, sound and vibration dampening, remodeling, and more.
Works on: wood, brick, metal, stone, vinyl, PVC, and more. May not be compatible with some plastics.
General directions
- Always wear eye protection, gloves, and proper work clothing when using Flex Foam. Cured foam is difficult to remove from skin, clothing, and other substrates.
- Make sure the area is clean, dry, and free of grease and oil.
- Shake the can for 60 seconds, then immediately attach the straw applicator.
- Test the pressure and expansion rate on a piece of scrap material before beginning your project.
- Fill the opening only up to 50%, as the foam will continue to expand after being dispensed. DO NOT overfill gaps and holes.
- Foam becomes tack-free in 10–15 minutes and fully cures in 8–12 hours, ready to trim, sand, and paint.
Helpful tips
- For waterproof and UV protection, we recommend adding a topcoat of Flex Seal Spray or Flex Seal Liquid.
Replacement nozzles
Extra applicator nozzles for your Flex Foam can, so you can keep a fresh one on hand for the next job.
Watch it work.
Check out our official commercial to see Flex Foam in action.
Questions?
Here’s what you need to know before you foam.
If you didn’t find the answer you’re looking for in our FAQs, our team is ready to help.
Ask usUsing it
No gun and no mixing, and the replaceable precision nozzles mean the can comes back out for the next job.
- Prepare the surface. Clean, dry and free of dust, oil and grease. Lightly mist porous surfaces with water for a better cure.
- Bring the can to room temperature. Around 68°F to 77°F works best. If it has been stored cold, let it warm up, then shake vigorously.
- Attach the nozzle and fill. Hold the can upside down and work from the bottom of the gap upward. Fill roughly 50–70% of the cavity and let it expand into the rest. Deep joints go in layers, with a light mist between them.
- Trim and finish. Cut away excess after cure, then sand and paint.
- Clean up while it is fresh. Cured foam only comes off mechanically.
Not when it is filled correctly. The expansion is controlled, with enough rise to fill the cavity without building excessive pressure against the frame, so window and door openings stay true. Fill a little over half and let the foam take the rest rather than packing it solid.
Yes. Cured foam is water and weather resistant and holds a service range from −40°F to 176°F. Protect any exterior bead from UV with an appropriate coating or paint. It is not intended for continuous water immersion.
It is not recommended for PE, PP, PTFE and certain other low-surface-energy plastics. It works on framing, block, concrete, brick, wood, metal, EPS/XPS and uPVC. Substrates should be sound, clean, dry and free of dust, oil and grease.
After it cures
It is tack-free in about 4 to 9 minutes and ready to cut somewhere between 18 and 40 minutes. Give it a full 24 hours to cure through before sanding or painting. These are typical figures. Cold or dry conditions and deep fills run longer.
Indoors, no. It cures bright white rather than the usual yellow-orange, so a finished joint already looks deliberate. Trim it, sand it flush and paint it only if you want it to disappear into the surrounding trim. Anything exposed outdoors should be coated or painted to protect it from UV.
Both. Sealing the gap stops the draft and the air infiltration, and the cured foam itself provides thermal and acoustic insulation, so a joint around a duct run or a rough opening ends up quieter as well as tighter.
Cleanup and safety
Remove fresh foam immediately with a suitable foam cleaner or a cleaning wipe. Once it has cured it can only be removed mechanically, so deal with drips while they are still wet. Wear gloves and cover anything you do not want it on.
It is a pressurized container, so keep it away from heat, sparks, open flame and smoking, and never expose it to temperatures above 122°F, freezing conditions or direct sunlight. Store it upright in a cool, dry place between 41°F and 86°F, and out of reach of children.
Use only in well-ventilated areas and avoid inhaling the vapors or spray. Wear gloves and eye protection, and avoid skin and eye contact. Refer to the SDS for complete health and safety information.
