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Showing 1-10 of 354 reviews(Verified Purchases). See all 371 reviews
This stuff is amazing: it's like silicone sealant that you apply with a brush. It's slightly thinner than silicone, so that you can easily brush it flat over a large area, but plenty thick enough to stay put when you brush it into cracks, grooves and gaps. I was particularly pleased how well it adhered to the irregular roof surface (asphalt shingles, flashing, and roof cement used for previous patches). Some of the shingles were damp, which didn't affect adhesion at all. The directions say you can apply this when it's raining, but I waited until there had been no rain for about 12 hours.

Here's how to do a perfect job:

1. Buy a package of foam brushes like these:  20-Piece Foam Brush Set, 2-Inch. 2 inches is the perfect width: narrow enough not to collapse when you push the sealant hard into cracks, but wide enough to spread nice layers of sealant over big flat surfaces. I used two foam brushes per quart: when one starts to self destruct from brushing into cracks and against rough shingles, toss it and grab a new one.

2. I used a leaf blower to remove all the leaves quickly.

3. For cleaning the roof, you also need a hand brush like this one: Rubbermaid Comm Prod 6342-00-SILV 8" Comm Counter Duster, or one that comes with a brush and dustpan set (you don't need the dustpan.) This is the ultimate tool for cleaning the roof, because it gets rid of all the loose stuff. That's the only cleaning you need to do: get rid of the loose dirt, stone granules and leaves. Make sure to keep the brush away from the sealant! I tried using a broom at first, but it didn't clean into the little cracks, which the whole reason I was up there. This hand brush works better. A paint brush could work as well.

4. USE RUBBER GLOVES! This stuff is SUPER STICKY. It is much tougher to get off your hands than silicon caulk. Also wear old clothes...and resist the urge to wipe your hands on your pants! I brought a rag for wiping.

5. The directions say you can spread a layer 1/8-1/4" thick (3-6 mm). I think if you spread a 1/4" thick layer, you are probably being sloppy and making a mess. 1/16"-1/8" (2-4 mm) is a good guideline.

6. Start at the visible cracks, and jab the sealant into the crack with the brush, then wipe sideways to fill the crack with sealant. It will stay where you put it, but the best way to get a good seal is to embed the sealant deeply into cracks, then brush a nice smooth layer over the top.

7. In some cases, you will be applying over previous sealant like black roofing cement. In my case, there were visible cracks several inches long in the old roofing cement patch. After sealing all the visible cracks (see #6 above), I painted a smooth layer over ALL the visible roofing cement, plus two inches or more beyond. If some of the old roofing cement patch is cracked, the rest will crack within a few years, so seal it now!

8. I had trouble removing the last bit of sealant from the jar. The foam brushes are a bit too short and too weak to scrape from the bottom corners. A paint stirring stick might help here.

9. Bring a trash bag with you onto the roof. As you finish with brushes and jars of sealant and rags and gloves, throw them immediately into the trash bag. Wipe your gloved hands on the inside surface of the bag. Carefully haul the bag straight to the trash can when you are done. You REALLY want to keep this stuff off your clothes, shoes, etc. and because it is clear, it is a bit harder to notice than black roofing cement.

10. I purchased two quart jars to seal around four roof vents. If you are going to the trouble of sealing the roof, buy plenty. I may buy the gallon size next time, but I'll always keep a quart jar around for emergency repairs.
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on August 14, 2016
Great product. Very easy to use. I had cracks in my decking on the balcony built above my laundry room. I used this to seal it. It appears to be a very good, solid seal and seems to be a product that will have very good wear. Of course, only the rainy season this fall will tell for sure, but I feel good about this!
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on October 14, 2016
This stuff is the best I have found yet..
Make sure you can leave a window open for a couple days..
Other than that it stops leaks on the spot.
I had to put some on from inside the house first.
That's why I had to open the window. And it stopped leaking. So I know it will work on top of the roof too.
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on April 29, 2016
This stuff is great I've used it on all kinds of stuff tin roof, pvc, back glass on truck that had been leaking, the list goes on and on.
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on May 24, 2016
Works best when ambient temp is over 55, but seals well and remains clear. You will need more than the coverage suggestions say though.
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on September 29, 2013
I bought a house several months ago, and it turns out the previous owner had "fixed up" the roof by placing new shingles here and there and nailed those shingles down by putting a nail straight through them. The owner then proceeded to paint the entire roof as well.
Turns out this caused significant leak issues. Water would get between the shingles and the paint would keep the water from getting back out. It would then leak through the hole created by the nail.

I wasn't quite fond of the idea of replacing the roof just yet, so I thought I'd give 'through the roof' a shot. This actually seems to have worked rather well. I just applied the sealant over the joint between shingles to keep water from getting underneath them. Since doing so (a few months ago now), the existing leaks have stopped, and I live in florida where it rains quite a lot.

I'm not sure if this will work long term (years), or if it'll need to be reapplied, but I just need it to hold me over til next year when I decide to have the roof replaced.
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on May 14, 2017
This is best product I've ever run up on it fixed my problem of a leaky porch roof that I've been fighting for years. Nothing I have tried worked. But this worked like a charm. Went on very easily and only used 1gal. For the whole valley. We've had several very hard rains and NO leaks.Love it. It came as predicted. Would and have recommended several people. I also used it to stop my fountain which is made of fiberglass and sits on ground no more leak of resivor tank Thank You.
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on January 22, 2017
I usually buy roof products to solve my leak problems, those kind of asphalt thing. It will only work for 1 month and here comes the leak again. When I used this product, leaks were gone and seems to be not cracking. At present, there is lots of rain in Los Angeles and I am free of leaks. I will wait for next year and see if this will hold for years and years and will post another review.
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on June 30, 2017
So far so good. I had some small drip leaks around screws on my patio roof. Used through the roof to seal around each screw and around the edges. I'm in Florida and we get very strong afternoon thunderstorms. The area's I sealed are no longer leaking. Plan to purchase more and seal the rest. It's been about 3 weeks now since applied, hopefully this will last longer than traditional caulk. Very happy at this time!
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on October 2, 2016
I used this product on my RV just this week. I did a first patch coat 4 days ago, and then a second coat last night. It rained this morning, and the product has worked flawlessly. Some of the cracks on the roof line were around 3/8ths of an inch wide. Yet Sashco flowed into and filled even that wide of a gap. I used the product on every crack and seam of the roof, and over all the previous patch material placed before. The worst spot was where my air conditioner sat on its pan. I did that yesterday. There was as much as 3/4ths of an inch gap below the pan. I stuffed that with Oakum, and then heavily slopped Sashco onto the roof/pan border, and pushed the mix into the Oakum and against the 1 inch lip of the pan. I put it on so thick that it likely will not set up for over a week. Around 12 hours later it started raining. The entire patch job has held, and amazingly the heavy use around the air conditioner pan has held, even when the pooling water reached over half way up the one inch lip of the pan. I had to throw several sheets on the roof to form a siphon to drain the pool around the air conditioner. Next year I will have to fix the sag on the roof. This product does everything it claims to do.
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