How does chimney flashing work

Chimney flashing is a type of roof flashing that creates a waterproof seal to protect your chimney and roof from water damage and penetration. Essentially, chimney flashing functions as weather stripping for your chimney and is made up of three major parts: step flashing, counter flashing—also called cap flashing—and base flashing. Step flashing is an L-shaped piece of metal that lies under the roofing shingles and along the brick of your masonry chimney. Counter or cap flashing is also an L-shaped metal piece, but it is designed to cover the step flashing and embedded into a groove cut in the chimney brickwork.

Base flashing is used at the joint between a vertical surface and the roofing surface, in this case the base of the chimney, guarding against water penetration. If the chimney flashing around your chimney fails and begins to leak it could cause serious damage to your roofing, attic, and even interior rooms. The chimney itself could even sustain damage if the chimney flashing begins to leak. Flashing is installed at the point where your chimney meets your roof and is made out of vinyl, aluminum, copper, or steel, depending on your roofing and the surrounding climate.

You can read about other parts of chimneys and fireplaces here. Properly installed chimney or roof flashing can last up to 30 years. Lifespan is determined by surrounding details like where you live, shape and size of your chimney, and the materials used to make it. Knowing what year your house was constructed helps keep track of the life of your chimney. They say that April showers bring May flowers, but this also means lots of rain and dampness.

Spring is the most common time for a chimney leak. Not Helpful 0 Helpful 3. How many inches of flashing should there be at the bottom, lying against the roof, on all four sides? For a skylight or chimney on a composition roof, there should be 6 inches on bottom and sides, 9 to 12 inches on top. Not Helpful 1 Helpful 1.

I had my metal roof replaced about 2 years ago. It is now leaking pretty badly around the chimney. There is no saddle on the back. Do you feel that is something the contractor should be responsible for fixing? Since it was two years ago, it is likely that the contractor is not liable nor responsible to fix it for free. For home improvement projects, contracts typically have some sort of warranty period, this period is typically at most only good for one year.

Check your contract and call them up to find out more. In some cases, if the product is faulty, the warranty may be longer. Include your email address to get a message when this question is answered. Measure the dimensions of the chimney and the slope of the roof before ordering the flashing pieces from a sheet metal company.

Helpful 0 Not Helpful 0. Submit a Tip All tip submissions are carefully reviewed before being published. Related wikiHows How to. How to. About This Article. Co-authored by:. Co-authors: 8. Updated: October 21, Categories: Fireplaces. In other languages Deutsch: Einen Schornstein abdichten. Nederlands: Zetwerk om een schoorsteen plaatsen.

Thanks to all authors for creating a page that has been read , times. Thank you! More reader stories Hide reader stories. I also recommend that my customers waterproof their brick chimneys every few years with a silicone-based sealer that can be applied with a garden sprayer.

Not all builders agree, but this is a great way to keep water from seeping into the brick. Is your roof protected from unexpected damages? See if a home warranty plan is right for you. Cookie banner We use cookies and other tracking technologies to improve your browsing experience on our site, show personalized content and targeted ads, analyze site traffic, and understand where our audiences come from.

By choosing I Accept , you consent to our use of cookies and other tracking technologies. Leakproof Flashing. By Danny Lipford. Pinterest Email Pocket Flipboard. Though these metals last for some time, they do have an expiration date that varies by wear. Chimney flashing consists of two metal panels. The base flashing is installed underneath the shingles and bent in an L-shape upward against the brick chimney.

Be sure your roofing contractor checks for breaks, cracks, or holes before moving forward. Once the first metal panel is installed, the second piece of flashing is set in place. We call this counter flashing. This counter flashing is bent down over the base flashing and embedded into a chimney mortar joint. This panel seals the top portion of the base flashing. Installation of chimney flashing can be challenging and that is why we recommend you enlist the help of a professional roofer.

Leaks from your chimney are not always so easily detected, but they can cause major structural damage if not taken care of readily. When moisture enters your roof it can penetrate your attic and possibly the ceiling area. Consistent moisture is known to cause wood rot, roof damage, attic issues, and drywall damage around the ceilings. If you notice any obvious issues, use safety precautions when accessing your attic or roof to check for leaks.

Now that you know what chimney flashing is, how it is installed, and how to check for leaks, when do you know when to repair or replace it? Since weather can be brutal on your chimney flashing, you will need to replace flashing that is missing or eroded. If you are having shingles repaired or replaced on your roof, it is always a good time to check on the flashing. Even though most flashing is made from durable metals, older chimney flashing might be rusted.