Back to Blog Repairs Chimney Leaks in San Antonio: Why They Happen and How to Fix Them
Mark WhiteJuly 10, 20254 min read If you have water stains on the ceiling near your chimney, your first instinct is to call a chimney company. But 90% of the time, chimney leaks are actually roof flashing failures, and a roofer is who you need.
The flashing around your chimney is a system of metal pieces that seal the gap between the chimney masonry and your roof surface. It's one of the most complex details on any roof, and it's the most common failure point.
Why Chimney Flashing Fails
San Antonio's temperature cycling expands and contracts your chimney masonry and your roof deck at different rates. Over time, this differential movement pulls the flashing sealant apart, creating gaps where water enters.
We also see failures from: improper original installation (step flashing skipped or incorrectly overlapped), sealant-only repairs (caulk is a temporary fix, not a permanent solution), and mortar deterioration in the chimney crown that lets water behind the flashing from above.
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A proper chimney flashing repair involves removing the old flashing, installing new step flashing integrated with counter-flashing set into the mortar joints, and sealing with high-grade polyurethane sealant. The chimney crown should also be inspected and repaired if cracked.
Cost: $500-$1,200 for most chimney flashing repairs. If the chimney crown needs work, add $300-$600. Compare that to the $5,000+ in interior water damage that an ignored chimney leak causes.
Call Legacy at (210) 272-7272 for a chimney flashing assessment.
Got a roofing question? Something keeping you up at night? (Besides that mysterious dripping sound?) Email me personally at mwhite@legacytx.com. I read and answer every single one.
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Owner, Legacy Home Improvements · San Antonio since 1999
Mark has been in the roofing business for over 25 years. He personally inspects homes, works with insurance adjusters, and answers every email at mwhite@legacytx.com.
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