Installation Details · FAQ

Should chimney flashing be replaced during a roof replacement?

Yes, always — even if it looks intact. The old flashing was installed against the old shingles. Underneath the new underlayment and at the new roof plane (even a quarter-inch difference from extra ice and water shield), the old flashing no longer sits where it needs to. Trill replaces chimney flashing on every full re-roof.

The replacement adds roughly $250 to $450 per chimney depending on chimney size and design (square versus rectangular versus angled). Re-using old flashing to save that money is the most common chimney-leak setup we see on roofs done by other contractors — the leak starts at year three or four when the new shingles have weathered enough to expose the misaligned old flashing edge. Worth doing right the first time.