Flex Seal MAX, 17 oz, 2-Pack, Clear, Stop Leaks Instantly, Waterproof Rubber Spray On Sealant Coating, Perfect for Gutters, Wood, RV, Campers, Roof Repair, Skylights, Windows, and More

Works well! Used it on flaking concrete after I cleaned it up & seems to have sealed it well. Also very easy to use.

Thanks to Mother Nature, and a moderately damaging hail storm, my camper trailer suffered some damage to the 2 roof vents, with some fairly large chunks completely knocked out. I had already replaced the roof vents in 2017, due to a worse hail storm, and wanted to consider an easier fix. So...I used Titebond glue to adhere strips of drywall repair mesh (comes in a long roll, like drywall tape) over the gaps and to stabilize the multiple cracks. I put a small piece of painters' blue masking tape on the inside of the vent where the mesh was open to the interior, as I couldn't find a good size chunk of the roof vent plastic. The following day I used the Flex Seal Max spray over the entire surface of both roof vents. I sprayed it on very thick, to completely cover the mesh tape. The consistency of this product is obviously thin enough to produce an easily-sprayed product, for better aesthetic coverage, but it was probably a bit too thin for my application. I also used a 2" disposable foam brush to try and get thicker coverage over the mesh taped areas, once the product had started to set-up. The product's solvent evaporates fairly quickly, so I made another spray pass over the hand-brushed areas for better looks, and in case I had disrupted the coverage, to avoid leaks. The job looks great and appears to be adequately sealed. I'm also hoping that the 'rubberized' coating may be more hail resistant. Plastics at Denver's altitude take a real beating from UV exposure, so I'll see how this idea pans out. This spray also may be a good idea as a preventative to avoid moderate hail damage. Update: after waiting several days for the Flex Seal to cure, I tried to remove the small strip of blue painters' tape from the inside of the roof vent. The Flex Seal stuck to it pretty bad, and stripped off a little of the product. Luckily, I still had some left in the large, 17oz can, and made another pass to seal off the few small holes. Hopefully I'm now done with this project!

PLEASE read to directions carefully because this stuff is full of dangerous and flammable chemicals. It does work for sealing leak causing cracks. Don't know how well it will last in sunlight but for a short term fix it seems to work fine.

This stuff works.

Easy to apply. Covered quickly

First, I will list my scores for Adhesion, Ease of use, and Water Resistance. Then, I will elaborate and give my final conclusions.Adhesion: 2/5Ease of use: 5/5Water resistance: 2/5Overall score: 3/5AdhesionThe initial coat stuck quite well with proper prep. I used denatured alcohol to clean the surface, then 60 grit sandpaper to rough the surface and help with bonding, and then another round of alcohol to clean dust. However, one coat will not give the desired results. Much like paint, areas lacking appropriate coverage are more visible when dry. This is where the adhesion becomes an issue. Proper prep, specially sanding, becomes difficult because this sealant is pliable even when dry. Its not possible to do more than the slightest scuff without the possibility of damaging the first coat. Due to the thick nature of the product, expect a lot of drips. The product is very runny fresh out of the can.Once the product is dry, the issues with adhesion aren't over. The commercials for flex seal (and the quality memes) make you believe the bond is like super glue on steroids. This is hardly the case. If there is any heat or any pressure this sealant will not hold. Heat causes it to soften, losing almost all integrity, and pressure will force water through the porous interior (caused by the aerosol delivery).Overall, the adhesion score is due to the drips on the second coat and beyond, and the lack of integrity at anything other then ideal (meaning low to no pressure and heat).Ease of useApart from drips making an even coat difficult on anything not planar to the ground, this is as easy to use as you think. The most difficult part of the process is prepping. The nozzle is fairly accurate and in my experience didn't clog. If you intend to use this sealant in a tight space, the can may be difficult to manipulate.While the can states its a skin irritant, it's not terrible if you get some on you. The toughest part will be peeling it off. Smell is comparable to paint. Tolerable to use with an n95, though respirator will be your best bet. Smell dissipates in an hour or less with ventilation. I do recommend using nitrile gloves and safety glasses.Overall, very easy to use.Water ReistanceAs mentioned in adhesion, any pressure will cause fluids to seep through the sealant. Depending on pressure, could be a sweat, could be a drip. Due to the viscous yet flowing fluid upon first use, even coats are difficult to achieve, which in turn effects sealing. There are pictures on the can of "recommended uses". One shows patching potentially leaking roof shingles, however, on the rear text on the can specifically states not to be used in roofing scenarios. While advertising a flexible barrier (which was attractive to me because I wanted a sealant that would withstand thermal expansion), the actual mechanic of flexing significantly compromises the seal. Hence, most likely, the warning against using it on roofs, since the can heat up to 160°F during summer.Overall, the score is based on the fact in nominal pressure and temperatures environments this will seal and hold out moisture, but in anything else the seal is questionable at best.The overall score of 3/5, and as the title alludes to, means that this sealant is meant for low stress sealing, specifically in areas that MAY leak (and not WILL leak). While not the best sealant, its easy use makes up for potentia shortcomings in other areas.

Very good product to seal cracks and leaks on my Rv trailer roof.