Flex Seal Spray Sealant Product Review

Flex Seal

Flex Seal

Use: Spray on rubber for sealing cracks.
Cost: $14.95 + $6.95 S&H = $21.90 total
Rating: ★★☆☆☆

Flex Seal is a liquid rubber sealant in a spray can which claims to be able to fill cracks and holes in everything from roofs to gutters to skylights with a waterproof seal once it has dried for 24 hours.

To test Flex Seal we sprayed it on cracks and joints in a sheet metal air conditioner drain pan, then allowed it to dry for two days. When we put water in the pan, some of the joints had pulled loose, causing the pan to leak.

While Flex Seal did a good job of coating the surface, the cracks in the sheet metal seams telegraphed back through.

Watch this video to find out more.

Danny Lipford: We’ve asked Tim Parker, a professional HVAC contractor, to supply us with a real world situation—a leaking air conditioner drain pan. We’re going to try and revive it with Flex Seal, the spray on sealant.

Tim Parker: I’ve seen, you know, the Flex Seal advertised on TV.

Danny Lipford: Right.

Tim Parker: I want to put it to the test myself.

Danny Lipford: Yeah, everybody ask me about it. We’re reinforcing this old pan by giving it a new bottom.

Tim Parker: Yeah, and what we’ll do is we’ll rivet this down.

Danny Lipford: OK.

Tim Parker: Then what we’ll do is kind of a reinforcement.

Danny Lipford: Oh, I got you, yeah.

Tim Parker: To go on here, and that will kind of give us another protection there for water to drain.

Danny Lipford: Nice sheet metal work there.

Tim Parker: Let’s try that.

Danny Lipford: It’s not as exciting as the screen door in the bottom of a boat demonstration they use on TV, but it’s a real world repair.

Tim Parker: Danny, this is kind of extreme. So if you’ve got just a pinhole, I’m thinking this works on this, it’ll work on a just a pinhole without removing the coil.

Danny Lipford: And probably that’s what you find most of the time.

Tim Parker: Right. If this is as good as it says it is, that ought to seal any of that little crack.

Danny Lipford: I think so, too. All right, I’ll give you the honor of going around the perimeter there.

Tim Parker: Yeah, let me try it.

Danny Lipford: It’s building up pretty well.

Tim Parker: It’s laying in there pretty good. We’re going to fill that whole gap in.

Danny Lipford: Well, Tim, they said to leave it there drying for about 24 hours. It’s been two days, so it looks like it applied fairly well.

Tim Parker: Yeah, that crack there that we had had, we had filled that in real well and that’s opened back up. That doesn’t look like it flexed very good to me.

Danny Lipford: Yeah, I’m a little concerned about that part of it and everything. Well, let’s pour a little water in this thing and see what you think. If you want to grab that, I’ll pull this drop cloth out, and we’ll see what happens here.

Tim Parker: We’ve got water, Danny.

Danny Lipford: Uh oh.

Tim Parker: We’ve got water. I was going to say that crack didn’t seal.

Danny Lipford: Hmm.

Tim Parker: It did not seal the gap.

Danny Lipford: After another good coat of Flex Seal and another 24 hours we poured on the water again. And it seems to hold for a moment, but then the water oozed out again. The upshot is this, Flex Seal does seem to apply easily and seal well it just doesn’t seem to be that flexible. In other word it isn’t the magic bullet the price and hype suggest. We give it 2 out of 5 stars.


  1. Had new tub install but, cannot keep a good seal around the tub and wall! Did not know at time but, contractor installed a tub was very lite in weight and has some flex to it. Even tried filling tub with water and then caulking with a quality caulk, letting it set for 72 hours before draining, only to still have the seal break away!!! I was wondering if flex seal would be a recommended product to use in order to solve my problem. Please advise as I have gone through this procedure 3 times in the past 5 years!!!!! Thank you so much !!!!!

  2. i have a patio sun roof seems are starting to leak would seal flex work for me just do the seams or the entire roof 14 x14 enclosure

  3. You shouldn’t expect the product to fill a large flexible gap. There is another product for that job called flex shot, which is a caulking compound equivalent. Had you used the product correctly, you would have sealed the pan. As a matter of fact, they should have riveted the flexible metal pieces together and then used the flex seal on it.
    Funny thing is if the contractor had not used any new sheet metal and just sealed the old pan with flex seal, I bet it would have worked fine.

  4. I have drafty windows slide left and right I’m afraid to caulk them afraid won’t open. What kind of flex would u use. I have a can of flex spray. Just don’t know what kind to use. Thank you.

  5. I don’t knpw about the prodct. I placed an order with Flex Seal over three weeks ago. Still waiting.
    Their customer {dis}service is terrible. I called the phone number on their website- all I get is a recording saying my order will ship in 30 days. They will not allow antone to talk to a person.
    I’m going to find a different product.

  6. Flex Seal is awesome! I use it every where possible. It has stopped my basement from leaking, windows, roof, RV everything with proper use. Definitely worth it, highly recommend.

  7. Kenneth did you ever get an answer to you question… I am having the same problem with my tub and my hubby though of using Flex Seal? did you try it and how did it work… Kenneth – September 13th, 2016 at 3:37 pm. Anyone else ever use Flex seal as a caulking for Tubs/showers? love to hear from you.

  8. I’m trying to decide between the spray and the tape. I need to seal a curved surface, the base for a basketball pole/hoop/backboard that needs to hold a lot of water for weight and stability.

    • Hi, Dom,
      Here’s “Today’s Homeowner” host Danny Lipford’s answer to your question:
      “Dom, No, I would not recommend it for that but instead consider using a two-part epoxy. Good luck with your project!”
      Thanks for writing to us!

    • Hi, Roy,
      Here’s “Today’s Homeowner” host Danny Lipford’s answer to your question:

      “Instead of the Flex Seal, I would recommend a duct mastic. You may also need to use metal foil tape prior to applying the mastic. Good luck with your project!”

      Thanks for writing to us!

  9. HI….. I have a air leak in my air matress.
    Will flex seal keep air after folding my matress ???????????
    Thanks in advance

  10. We had a crack in our fish pond and leakers. So we drained it cleaned the spot let it to dry. We got the tape and caulk bond seal and it doesn’t work in our fish pond. Tape don’t stick and the caulk come off in days and gets in pump.
    Just want to let you know.

    Thanks Lisa Foust

  11. Will any of these products work on a small area to stop peeling on the vinyl/faux leather of my recliner? Will it stick to the surface or just mess I up. The recliner looks new and it isn’t too old, just maybe 3 years old. I’m trying to find something to fix the peeling and stop it from getting worse. Its a good, nice looking chair and don’t want to replace it. Thanks.


Please enter your comment!
Please enter your name here