ChimneyRx 300119 Masonry Chimney Water Repellent - Siloxane Based, Non-Film-Forming, Breathable, and Transparent Waterproof Coating for Brick Chimneys & Other Vertical Surfaces - 1 Gallon

Works as advertised. I sprayed it on 5 years ago and no more water intrusion

I had water leaking into my family room through the chimney. For some reason the upper ten rows of brick had become porous and with some occasional cracks. The real problem however was the cracked crown. The chimney footprint is approximately 65 inches by 30 inches. I removed the old crown by cutting grooves using a 4" diamond wheel in a small right angle grinder and chiseling off the old cracked crown. I screwed together a wooden form for the new crown so that it now overhangs the chimney by 3" on all four sides and approximately 2-1/2 ' thick at the edges. a drip groove was made using 1/4 x 1/4 wide wooden strips nailed to the bottom of the form approximately 3/4' from the form's walls.These pieces should be tapered so that they will be easily removed after casting the new cement. I used high strength cement tapered upward toward the chimney flue. Two layers of corrugated cardboard were used to create a space between the new cement and the flue. After casting the cardboard was removed and the space filled with silicone caulk. This is critical to allow for thermal expansion and contraction. The worst part of the job was hauling the 800 lbs of wet cement to the roof. Fortunately I own a ranch house and from my deck to the roof is only about 11 feet. I rented a a lift for the day that was easily hand cranked up to the roof line. It was well worth the price. After repairing all the broken and missing mortar joints I sprayed the entire chimney with the chimney water repellent using a garden sprayer. This process was very easy . My bricks were so "thirsty" that I ran out of liquid halfway through the job. Fortunately I started half way up the chimney side and worked my self up to the crown. I was just able to cover the top half with two coats. I followed this by filling minor cracks with the Masonry Crack and Joint Sealer made by the same company. I highly recommend both products.

I patched every place I could see with Mortar sealant and I still had a leak. So, this product worked in stopping the leak. I purchased a new pump-up spray jug and sprayed down the chimney and we had a small shower and No leaks, the next day it rained almost 2 inches and "NO LEAKS". Hip-Hip Hooray. Note: I was told it might change the color the bricks, so I did the entire wall along with fireplace, and unless you're an expert - I can't tell it did anything.

Easy to apply hopefully it will last

Works for 1 year. I sprayed it on my shingle roof it’s self along with my stone chimney.

My brick chimney started leaking after 30+ years. Use of chimney cleaner and sealant made the job and fixed the leak and water stains formation! Great product, may be overpriced, but make the job. I recommend this product.

I just applied it, so have no idea how well it works. It was easy to apply though and a gallon goes a long way. You should only need one gallon. This product seeps into the cement/concrete, then hardens. It's not meant to seal cracks or anything. You will need to apply a lot to be sure plenty has soaked in. I plan to use this on my sea wall in the fall.

I've been having trouble with water seeping through my fireplace chimney. I painted this on during the summer, and so far it seems to be holding. It's completely clear and didn't leave any visible signs of having been applied. I think I'll start using it every year just to place it safe.