300016 Masonry Crack and Concrete Joint Filler – Elastomeric & Waterproof Mortar Repair Sealant for Chimneys, Joints of Brick, Block & Stone Walls – 1 Pint

Worked really well to temporarily seal our chimney to stop leaks

Saved me thousands in repairs to the chimney.Noticed that the chimney was wet in the attic area and had a drip inside of the fireplace. Was very concerned and called around to multiple repair men and was qouted well above $1000 to repair it. I did the repairs myself in multiple stages. This was about stage three when I discovered some cracks. Applied this to the chimney and boom all problems disappered.I will tell you this doing it yourself and ensuring that you have the right product for the right problem is key.

I have not applied to all the chimney's mortar joints yet, but it goes on easy.

Used on a brick chimney. Some cracks between brick and mortar were up to 1/16" wide, none larger that that. For the 1/16 inch cracks, I had to apply 3 coats to get the product to span 1/16" which is 1/2 of what product claims to be able to fill. I tried to apply extra heavy to prevent reapplication need and could not get product to fill perfectly on first attempt no matter the application. As a contractor labor was more costly than the product, so as such I was disappointed in this aspect of the product. Besides the above comment, estimated coverage was accurate as per Mfr. info provided, workability was good and I applied on a warm summer day, and all cured as per Mfr. literature.....some clear....some whitish depending upon thickness applied. This chimney did not have any major water leaks before, so cannot testify to efficacy of the product....this was the best engineered product I could find as it remains breathable....nothing of this type was for sale at local brickyards or home centers. End of day I think worth spending time to apply 3 coats of a breathable product where needed....just wish I knew this in advance to better estimate job labor costs involved. Found a toothbrush to be the best applicator tool vs. traditional paint brush types as the many short stiff bristles held more product minimizing having to dip as often....yet not so large as to waste product on areas not needing crack fill.

Work quite well and seems to be protecting my chimney fro mthe encroaching winter weather. Eventually dries clearer with time, though constant " flashing" as its called in the biz whe na shiny sheen appears on surfaces, persists at times of bright sunlight. Still, it proves its there even with only 2 layers.

Great product are use the whole chimney Rx system to waterproof my very problematic brick chimney... This was just part of the process and all combined the system is excellent

Very hard to remove. I wish I had not bought this product! I you're going to do it, I would say you need to apply 3 coats.

Thick and went on as described. I think it's going to work.