2025-11-24 – Weekly Roofing News : Diagnosing chimney leaks

Last week in the roofing community, discussions ranged from technical specifications to practical challenges on the job site. The community delved into the nuances of roofing materials and their interactions, particularly in adverse weather conditions. There was also a focus on troubleshooting leaks and damage in older roofing systems, alongside logistical challenges of coordinating crews with unpredictable weather forecasts.


This Week’s Hot Topics

Dehumidifier vs. chimney leak
Is it a humidity problem or a leaking chimney? Members are sharing diagnostic tips to differentiate between the two situations, which can often present similar symptoms.

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Ridge bedding spec for clay tile re-roofs
A detailed discussion on the best practices for ridge bedding in clay tile re-roofs is underway, highlighting the importance of correct specifications for durability.

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CTE and galvanic charts for coastal specs
Understanding material compatibility in coastal environments is crucial, and this thread dives into the thermal expansion and galvanic corrosion considerations for roofing.

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Hail-cracked ridge tiles on a 1927 barrel roof
Addressing damage on older roofs requires a special touch. This topic explores repair strategies for hail-damaged ridge tiles on historical buildings.

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Two crews, one lift, and the forecast
Managing resources efficiently is key, especially with changing weather. This conversation offers practical advice for coordinating multiple teams with shared equipment.

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Looking forward to seeing how these discussions evolve. Have a productive week!

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On older chimneys, I isolate with a hose test: 5 minutes on brick/mortar, then step flashing, then the back pan/cricket — don’t jump upslope. If it only shows in wind-driven rain, it’s almost always the back pan or a shallow reglet; we swap in a soldered pan and cut new counterflashing, not caulk. @RooferDan this killed three callbacks for us last week on a 1928 stack.

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@Guide good call; on older brick, hairline crown cracks fooled us — $25 moisture meter confirmed it.

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And , chimney leaks drive me nuts. Before tearing into flashing, I do a quick ‘cap test’: zip-tie a contractor bag over the cap for one rainy night — if the stain pauses, it’s top-entry via the cap/liner, not the roof; if it doesn’t, I trace from the attic with a $30 borescope to see which plane is wet, @Guide. Have you seen corroded cap screens kicking ‘wind-driven rain’ sideways into the flue?

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FLIR One caught a cold spot after ‘adverse weather’; porous brick, not flashing — still verify with a quick spray, @Jae.

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