All it takes is one rainstorm to reveal that your chimney has a leak. Chimney flashing is a metal strip that protects the joint between your roof and chimney.
A professional should repair the leaks caused by flashing failures. This is an important chimney project because leaks lead to water damage, promoting toxic mold growth.
Copper Flashing
The rust-resistant metal flashing is cut to fit and fastened under shingles and around vulnerable roof areas like chimneys or dormers. Copper flashing lasts longer than aluminum and oxidizes to a green patina that many homeowners find charming.
Moisture penetration through flashing can cause leaks in the building envelope and other components. Flashing prevents this by diverting moisture to the exterior at critical points where masonry, siding or other materials meet.
Flashing can be made of a variety of materials to suit the situation, including copper, aluminum and galvanized steel. Copper is traditionally used for flashing because it has a long lifespan and resists corrosion better than other metals.
Bare copper costs more, though, so it’s typically paired with other roofing materials to add contrast and visual interest to the home. It’s also possible to get the look of bare copper without the cost by using lower-purity copper alloys. These have the same durability as pure copper but are less expensive.
Aluminum Flashing
The flashing system also includes a counterflashing that wraps over the base of the chimney and directs falling rainwater away from it.
This protects the chimney against water penetration that could otherwise damage your roof, attic, and interior walls.
You can get a good idea of how well your flashing is performing by looking for rust spots on the counterflashing.
You’ll also want to look for accumulated water at the fireplace base, damper rust, and moisture stains on ceilings in rooms that open to the chimney area.
Chimney flashing is an essential part of a functional, safe, and efficient chimney system. Keeping the flashing in good condition is crucial for protecting your roof and home from water damage.
However, working on the roof and bending metal flashing is not for the faint of heart. For this reason, we recommend hiring a professional roofer to install or replace your chimney flashing.
They know how to measure, bend, and seal sheet metal flashing for a job that looks great and lasts for years.
Galvanized Flashing
Many different types of flashing can be found on a roof, each serving its own purpose. Flashing is thin sheets of impervious metal bent into shapes to seal joints and prevent leaks at junctures where the materials of the roof meet.
The junctures are often places where features such as chimneys, vent pipes or skylights penetrate the roof.
These junctures tend to expand and contract with changes in weather, making it difficult to seal them tightly. Flashing solves this problem by lining the area with pieces of metal that overlap like fish scales.
The lowest piece is called the base flashing (also apron flashing) and the top is called counter flashing or cap flashing.
It’s important to use the right flashing material, because copper is corrosion-resistant and will last longer than galvanized steel.
It’s also best to avoid using aluminum or galvanized nails in contact with pressure-treated wood, because the combination can lead to galvanic corrosion, a problem that occurs when different metals in contact with each other.
Lead Flashing
Lead is a durable, malleable and versatile material that has been used for flashings for centuries. It can be shaped and formed to fit most angles in a roof.
Unlike some other metals, it is not as susceptible to cracking due to expansion and contraction.
Flashings are commonly seen on chimneys, dormer windows, and walls that abut the roof.
They are fitted primarily to decrease water penetration at these points and help reduce the risk of internal damp problems.
When fitted correctly, lead flashing should overlap by a minimum of 100mm. This will help to prevent the formation of water creep underneath the lead, as well as protect it from damage caused by prevailing high winds or driving rain.
When it comes to chimney flashing, there are two main types; base and counter flashing. Base flashing is a series of L-shaped pieces that sit under the shingles around the base of the chimney.
Counter flashing is a piece built into the chimney that is installed above and overlaps the base flashing.
Contact Flashing Repair Experts
If you are looking to repair your chimney flashing, look no further than stone and brick masonry. We offer the most competitive prices for all kinds of chimney repairs, along with a quality of work that is unmatched.