What Happens to Your Chimney When You Replace Your Roof

If you're planning a roof replacement, you might be wondering what happens to your chimney during the process. While the chimney itself typically stays in place, the materials connecting it to your roof need to be carefully inspected and, in some cases, replaced. These details are important in preventing leaks and protecting your home from water damage.

Understanding how your chimney is handled during a roof replacement can help you know what to expect and ensure the job is done properly.

The Old Flashing Comes Off

Flashing is the metal that seals the joint between your chimney and your roof. During a proper replacement, the old flashing is removed along with the old shingles. That gives the crew a clear look at the roof deck and masonry around the chimney, where hidden rot, soft wood, or water damage often turns up.

Skipping this step means building a new roof around a problem no one has seen.

New Flashing Goes On

Chimney flashing is a two-part system:

• Step flashing is woven in with each course of shingles along the sides of the chimney, so water runs down and away rather than behind the shingles.
• Counter flashing is set into the mortar joints of the chimney and folds down over the step flashing, sealing the top edge.

Together, the two layers allow the roof and chimney to move independently as the house settles and temperatures change, without opening a gap for water. Ice and water shields are also installed around the chimney base before any flashing goes down, adding a second line of defense against wind-driven rain and ice dams.

Why Reusing Old Flashing Is a Shortcut That Leads to Leaks

Old flashing has already spent years exposed to New England weather. It may be rusted, bent, or pulled loose from the mortar. Even flashing that looks fine was sized and shaped for your old shingles, not your new ones, so it rarely sits correctly against the new roof. Sealant applied to cover the gaps dries out and cracks within a few seasons.

The result is a brand new roof with a leak at its most vulnerable point. Reusing flashing can also put your warranty at risk, since manufacturers like GAF and CertainTeed set specific installation requirements for coverage to apply.

Crickets for Wider Chimneys

A cricket, sometimes called a saddle, is a small peaked structure built on the uphill side of a chimney. Without one, water, snow, and debris collect against the back of the chimney and sit there. In Massachusetts winters, that pooled water freezes, thaws, and works its way into every seam.

The cricket splits the flow and directs water around the chimney instead of against it. Building code generally requires a cricket on chimneys wider than 30 inches, but even smaller chimneys benefit from one in a climate with heavy snow. A roof replacement is the ideal time to add one, since the area is already open.

A Chance to Inspect the Masonry

With the shingles and flashing removed, your contractor can see the full condition of the chimney where it meets the roof. Cracked mortar, loose bricks, and a damaged crown are easier to address before the new roof goes on than after. Repairing the chimney first protects your investment in the roof.

Replace Your Roof With Eyles Contracting Inc.