Roof Problems · Damaged Flashing
Flashing is a few dollars of metal protecting the most vulnerable joints on your roof. When it fails, leaks follow — here's how to spot it early.
Flashing is the metal (usually aluminum or galvanized steel) at every roof interruption: chimneys, skylights, wall intersections, plumbing vents, and valleys. From the ground or a ladder, look for metal that is bent, lifted, rusted through, or separated from the surface it should hug, and for cracked roofing cement smeared over joints (a sign of past patch attempts).
Inside, flashing leaks show as stains near chimneys, around skylight frames, or along the line where an addition meets the main house.
Illinois is hard on flashing. Freeze-thaw cycles — water getting into a joint, freezing, expanding, repeat dozens of times per winter — pry metal and sealants apart year after year. Galvanized flashing eventually rusts through, and the roofing cement used in older installations dries, shrinks, and cracks.
Installation quality matters enormously: proper chimney flashing is a two-part system (step flashing woven with the shingles plus counter-flashing cut into the mortar joints). Caulk-only 'flashing' is a shortcut with a short life, and it's one of the most common findings on roofs we inspect.
Common causes
Visible rust-through, separation you can slip a finger into, or any interior staining near a flashed area means schedule a repair soon — flashing leaks only get bigger, and they quietly rot the decking around the penetration.
Flashing should also be evaluated any time the roof is replaced: reusing old flashing on a new roof is a false economy that strands the weakest component under the newest materials.
Flashing repair is almost always a repair, not a roof replacement: reflashing a chimney, replacing pipe boots, or reworking a wall intersection are discrete jobs. The exception is when flashing failure has gone on long enough to rot the surrounding decking — then a localized tear-off and rebuild of that area is needed.
As a short-term measure, yes — months, not years. Proper flashing is mechanical (metal layered with the shingles and into masonry), not chemical. Caulk over a bad flashing detail is a recurring appointment.
Quality aluminum or copper flashing installed correctly can match the life of the roof. Galvanized steel and mastic-heavy installations commonly fail in 10-15 years in our climate — often before the shingles around them.
The masonry itself: cracked mortar crowns and porous brick absorb water that then appears inside as a 'flashing leak.' A proper diagnosis checks the whole chimney, not just the metal at its base.
Get a free, no-obligation inspection. We'll confirm the diagnosis, show you photos of what we find, and give you honest options.
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