Chimney Flashing

A chimney is one of the largest openings that passes through a roof, making it one of the most vulnerable areas for water intrusion. Proper chimney flashing is not a single piece of metal—it is a system of flashings that work together to keep water out.

A properly flashed chimney may include:

• Apron flashing at the front of the chimney

• Step flashing along both sides

• Counter flashing embedded into the chimney mortar joints

• Back pan or cricket flashing on the uphill side of larger chimneys

Each piece has a specific job, but together they direct water safely around the chimney and back onto the shingles.

What Makes a Proper Chimney Flashing System?

Many chimney leaks occur because one or more flashing components are missing, damaged, or improperly installed.

A properly installed chimney flashing system should:

• Direct water around the chimney

• Overlap correctly with the shingles

• Allow the roof and chimney to expand and contract independently

• Prevent water from entering behind the flashing

• Follow manufacturer installation requirements and applicable building codes

Proper installation is just as important as the flashing materials themselves.

When Is a Chimney Cricket Needed?

A chimney cricket, sometimes called a saddle, is a small peaked structure installed on the uphill side of certain chimneys.

Its purpose is to divide and redirect water around the chimney instead of allowing water, leaves, snow, and debris to collect behind it.

Building codes generally require a cricket on chimneys that are 30 inches or wider, although one may also be beneficial on smaller chimneys depending on the roof design.

Typical Cost

Chimney flashing is typically included as part of a complete roof replacement when work is being performed around the chimney.

The cost depends on the size of the chimney, the existing flashing conditions, roof pitch, and whether masonry repairs or a chimney cricket are required.

Because chimney flashing is a complete system, replacing only one component may not always provide the best long-term solution.

Benefits

• Helps prevent roof leaks

• Directs water around the chimney

• Protects the roof deck and interior

• Reduces the risk of moisture damage

• Works with the shingles to create a watertight system

• Improves long-term roof performance

• Helps extend the life of the roofing system

Why It Matters in Michigan

Michigan's heavy rain, lake-effect snow, ice, and freeze-thaw cycles place constant stress on chimney flashings.

Because chimneys interrupt the natural flow of water down the roof, proper flashing is essential for preventing leaks. When installed correctly, the flashing system helps move water around the chimney and safely back onto the roof surface.

Our Recommendation

At VanderLaans, we inspect every chimney during a roof replacement to determine whether the existing flashing can continue to perform or should be replaced.

We install chimney flashing in accordance with manufacturer specifications and applicable building codes. Our goal is to create a complete flashing system that works together with the shingles, underlayment, and other roof components to provide long-term protection.

Did You Know?

Many homeowners assume a chimney leak means the masonry is failing. In reality, leaks are often caused by damaged or improperly installed flashing. A properly designed flashing system, including step flashing, counter flashing, apron flashing, and, when needed, a chimney cricket, is one of the best ways to keep water out around your chimney.