Waterproofing
A masonry chimney showing severe water damage.
Over time, water “eats” masonry chimneys. Mortar joints between bricks are dissolved by water; bricks are slowly broken apart by water moving inside the brick. Water moving within bricks causes effluorescence (mineral deposits on the outside of bricks, brought from the inside by water movement) and spalling (flaking or chipping of brick, caused by water freezing inside the brick and expanding, causing pieces of brick to flake away). Deteriorated masonry allows water to enter the chimney structure, causing more damage.
There are multiple ways to prevent or mitigate water damage. The most important is to have a good quality chimney cap, which protects the flue and the top of the chimney from water entry. The second most important is to keep your masonry in good repair. A waterproofing treatment can help seal masonry chimneys against water entry without changing the appearance of the masonry. There are several different kinds of waterproofing agent. Our favorite right now is made by Professional Products of Kansas:
A masonry chimney with severe mortar deterioration.
PROFESSIONAL® Water Sealant has been manufactured since 1987. It is a RTV silicone rubber water repellent that has been successfully applied to buildings, bridges, highway sound walls, decks, fences, and many other types of surfaces in cities and towns in North America and abroad to protect against water intrusion and/or graffiti. PROFESSIONAL® Water Sealant is an inorganic sealant that bonds naturally to a variety of surfaces. Once applied it creates a long lasting, invisible barrier preventing damage caused by moisture.
PROFESSIONAL® Water Sealant provides your structure with the best protection money can buy … only nature protects better.
Professional Water Sealant is recognized as an industry standard by architects, engineers, contractors, and building owners for its superior above grade water repellent capabilities. It is an extremely long lasting, penetrating, water repellent product formulated by using RTV silicone rubber.
This chimney is covered in moss, evidence that the masonry structure is holding water.
- Transparent Dries to a clear, flat finish.
- Quick Drying Starts to cure within 2 hours.
- Seals Any Porous Substrate Developed for use on above grade horizontal and vertical surfaces such as: brick, block, concrete, and stone.
- Long Lasting Waterproofing Protection Penetrates into the capillary system to permanently bond with the substrate.
- Durable…Non-Sacrificial Because silicone rubber is inorganic, there is no deterioration from ultraviolet rays, ozone, salt spray, acid rain, etc.
- 400% Elongation Expands and contracts with building movements and temperature extremes…bridging hairline cracks.
- Breathable…High Perm Rate Allows moisture vapor to escape while prohibiting liquid penetration. Prohibits freeze/thaw damage.
Waterproofers can be applied only when the weather is above about 40 degrees Fahrenheit; otherwise they will not cure properly. Barnhill Chimney generally schedules waterproofing treatments in the spring and summer months. Waterproofing does not take long to apply, cures within a week (depending on the brand) and lasts from two to ten years depending on the brand, the chimney, the weather, and other factors. If your masonry chimney is showing early signs of water damage, a prompt waterproofing treatment can help prevent further deterioration and prolong the life of your chimney.
