---
product_id: 8120729
title: "Masonry Chimney Water Repellent"
brand: "chimneyrx"
price: "£61.67"
currency: GBP
in_stock: true
reviews_count: 8
category: "Chimneyrx"
url: https://www.desertcart.co.uk/products/8120729-masonry-chimney-water-repellent
store_origin: GB
region: United Kingdom
---

# Lasts years, chemical bond Penetrates 1/4 inch deep Breathable, non-film barrier Masonry Chimney Water Repellent

**Brand:** chimneyrx
**Price:** £61.67
**Availability:** ✅ In Stock

## Summary

> 🧱 Keep your chimney dry and flawless—because your home deserves the best!

## Quick Answers

- **What is this?** Masonry Chimney Water Repellent by chimneyrx
- **How much does it cost?** £61.67 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.co.uk](https://www.desertcart.co.uk/products/8120729-masonry-chimney-water-repellent)

## Best For

- chimneyrx enthusiasts

## Why This Product

- Trusted chimneyrx brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Invisible Protection:** Transparent formula keeps your brick’s natural look intact—no film, no fuss
- • **Long-Term Durability:** Chemically bonds with masonry for years of reliable water repellency
- • **Effortless Application:** Spray on easily with pump or airless sprayer; cleans up with soap and water
- • **Breathable Waterproofing:** Allows moisture vapor escape to prevent freeze-thaw damage and spalling
- • **Deep Siloxane Penetration:** Seals up to 1/4 inch inside masonry for unmatched water defense

## Overview

ChimneyRx 300119 is a siloxane-based, breathable masonry water repellent that penetrates deeply into brick and concrete surfaces. It forms a transparent, non-film barrier that prevents water intrusion while allowing moisture vapor to escape, protecting chimneys from freeze-thaw damage and spalling. Easy to apply and long-lasting, this 1-gallon sealer covers approximately 40 sq. ft. and ensures durable, invisible protection for years.

## Description

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

Review: Works well to stop water seepage - Works as advertised. I sprayed it on 5 years ago and no more water intrusion
Review: These pieces should be tapered so that they will be easily removed after casting the new cement - 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.

## Features

- ADVANCED SILOXANE FORMULA: Siloxane masonry sealer deeply penetrates up to 1/4 inch into masonry and concrete, creating a strong, breathable water repellent barrier that provides lasting protection without altering the appearance of brick or stone
- BREATHABLE PROTECTION: Unlike film-forming sealers, ChimneyRx waterproof sealer allows water vapors to escape, preventing trapped moisture, which leads to spalling and scaling, while reducing the risk of freeze-thaw damage during colder months
- DURABLE & LONG LASTING: Our chimney waterproofing sealant forms strong chemical bonds beneath the surface, becoming a part of the physical structure, providing long-lasting protection against water damage to chimneys, ensuring years of defense
- EASY APPLICATION & CLEANUP: Apply the chimney sealer with a pump or airless sprayer; lay a drop cloth around the base, spray from the bottom up, and cover thoroughly; apply a second coat within 3-5 minutes; cleanup is easy with just soap and water
- DRY TIME & COVERAGE: This masonry sealant covers approximately 40 sq. ft. per gallon; apply in temperatures between 40-90°F, allow 2-6 hours drying time depending on humidity for optimal protection (apply at least 6 hours before rainfall)

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B0060BUZ9E |
| Additional Features | Waterproofing |
| Best Sellers Rank | #54,976 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #183 in Hardware Sealers |
| Brand | CHIMNEYRX |
| Brand Name | CHIMNEYRX |
| Color | White |
| Controls Type | Push Button |
| Customer Reviews | 4.7 out of 5 stars 705 Reviews |
| Included Components | 1 Gallon |
| Item Dimensions D x W x H | 4"D x 7"W x 12"H |
| Manufacturer | CHIMNEYRX |
| Manufacturer Part Number | 300119 |
| Material | concrete |
| Material Type | concrete |
| Mounting Type | Wall Mount |
| Product Dimensions | 4"D x 7"W x 12"H |
| Special Feature | Waterproofing |
| Specification Met | rx |
| UPC | 709057221283 |
| Vent Hood Design | Wall Mounted Canopy Hood |
| Ventilation Type | Ductless/Recirculating |

## Product Details

- **Brand:** CHIMNEYRX
- **Material:** concrete
- **Mounting Type:** Wall Mount
- **Product Dimensions:** 4"D x 7"W x 12"H
- **Special Feature:** Waterproofing

## Images

![Masonry Chimney Water Repellent - Image 1](https://m.media-amazon.com/images/I/61BkjhoLyzL.jpg)

## Questions & Answers

**Q: Can I use this to seal the top of my chimney?**
A: This product is for sealing bricks which is fine for the brick part of the chimney. For the crown you should use this product; http://www.amazon.com/ChimneyRx-Brushable-Masonry-Fireplace-Repair/dp/B004XJYJBA/ref=sr_1_1?s=hi&ie=UTF8&qid=1459433037&sr=1-1&keywords=ChimneyRx+Brushable+Masonry+Fireplace+Crown+Repair

**Q: is this product made by system savers in richmond indiana?**
A: Yes it is!!!

**Q: It says vertical surfaces.  I wonder if I can use it on our brick front stoop and steps?**
A: It works on vertical and horizontal surfaces but is designed to shed water from vertical surfaces better and won't protect from standing water on horizontal surfaces.

**Q: Is this available in larger quantities ?**
A: No, it is not available in larger quantities.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Works well to stop water seepage
*by D***3 on April 24, 2026*

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

### ⭐⭐⭐⭐⭐ These pieces should be tapered so that they will be easily removed after casting the new cement
*by G***F on November 7, 2016*

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.

### ⭐⭐⭐⭐⭐ Fireplace water leak eliminated
*by B***T on July 1, 2025*

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.

## Frequently Bought Together

- ChimneyRx 300119 Masonry Chimney Water Repellent - Siloxane Based, Non-Film-Forming, Breathable, and Transparent Waterproof Coating for Brick Chimneys & Other Vertical Surfaces - 1 Gallon
- ChimneyRx 300014 Brushable Chimney Crown Repair – Elastomeric & Waterproof Coating for Crowns & Masonry - Fast-Setting & Long-Lasting Protection Crack & Leak Prevention - 1 Gallon

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*Product available on Desertcart United Kingdom*
*Store origin: GB*
*Last updated: 2026-07-16*