Water entry frequently comes from three common areas on chimneys. Chimney crowns, chimney flashing, and brick chimney leaks. Different factors can affect a chimney’s ability to resist water penetration. Factors such as the age of the chimney, the type of construction materials used, and the workmanship. In this article, we are going to reveal some specific problem areas and how you can solve your own leaky chimney.

Chimney Crown Leaks

Firstly, most chimney crowns leak due to improper construction or materials that were used. Over time, chimney crowns could crack or break off, allowing water to soak in and come inside the chase. This water can run down the chimney and absorb into the inside of your house. Additionally, crowns are supposed to be made of concrete but are frequently made from mortar instead to save time and money.

The problem with mortar is it is not as dense or strong as concrete and is likely to absorb water. If the crown is in too bad of shape, a replacement will in the near future. This repair can usually be priced anywhere between  $500-$2,000. However, in reality, the chimney crown is at the very top of the chimney and does get exposed to all elements of the weather and takes more abuse from the weather than any other part of the chimney chase.

Copper Outside Mount Cap

If there are some severe cracks, or missing pieces of the crown, at American Chimney & Masonry we recommend installing an Outside Mount Cap. This is most comparable to walking down the street with a newspaper over your head versus an umbrella. We all know that an umbrella would be a better option as it fully covers the area.


Chimney Flashing Leaks

chimney flashing leaks

Chimney flashings are another potential source of water leaks. Where the chimney meets the roofline is a particularly weak spot for water penetration because if the flashing was not installed correctly with the right material it may fail to do its job of shedding the water. 

The best material for flashing would be copper or stainless steel. Copper has the ability to be easily worked and shaped and can withstand wide temperature ranges without buckling or warping. 
Stainless steel is not as easy to work with as copper but it can be firmed and shaped and still provides water resistance.

Over time, as the chimney flashing deteriorates whether it’s due to the weather or the different materials such as galvanized steel and/or aluminum, water can gradually begin to seep into that joint and into your house, ruining drywall, causing wood rot and mold growth.

There’s a product called FlashSeal that you can apply on top of the chimney flashing to seal up this joint. There’s a mesh fabric that can also be applied underneath that makes it even stronger.

Brick Chimney Leaks

brick chimney leaksThe last problem area is the bricks and mortar joints. There are many different types of brick out there. The softer and more porous the brick, the more likely it is to absorb moisture to cause a leaky chimney. Mortar joints can also be another problem area. Many times, the mortar mix was made with too much sand, causing it to soak up water like a sponge.

Also, many times the mortar joints are struck too shallow, causing water to be able to quickly absorb and pass through the thin layer of mortar. To prevent water penetration in brick and mortar joints, try a waterproofing product called ChimneySaver. It’s a breathable water repellent that you spray on your chimney with a pump-up sprayer. It actually forms a chemical bond with your masonry about 1/4″ below the surface, making the masonry repel water for 5-10 years.

By protecting the chimney crown, flashing and brick and mortar, you’ll save yourself the expense of leaky chimney water damage and eventual chimney replacement. Water damage can cause over $1 Billion in damages every year. In most cases, this damage can be avoided by a little preventative maintenance once every 5-10 years.