Roof-to-Chimney Waterproofing
Where a chimney meets the roof is one of the most leak-prone areas on any house, simply because it's a rigid masonry structure penetrating a roof surface that expands and contracts with temperature. Flashing at this junction is built in layers — base flashing, counter flashing, and step flashing along the sides — and each one has to do its part for the whole assembly to shed water correctly.
Flashing failure often shows up as a stain on a ceiling or wall near the chimney long before anyone thinks to look at the roof itself. We repair and replace chimney flashing as a system, addressing corroded metal, failed sealant, and mortar joint issues at the counter flashing reglet where it ties into the masonry.
If the flashing metal itself is in reasonable condition but the sealant at the counter flashing joint has cracked or pulled away, a resealing can resolve the leak. If the metal is corroded, improperly installed originally, or has been patched repeatedly with sealant over the years, a full flashing replacement is the more durable fix rather than another temporary reseal.
Replacing the individual overlapping metal pieces along the sides of the chimney that direct water down and away from the masonry-to-roof junction.
Repairing or replacing the metal flashing set into the chimney's mortar joints that overlaps the step flashing and seals the top edge of the assembly.
Replacing the flashing piece at the front, downhill side of the chimney, a high-water-volume area that takes significant wear over time.
Removing old, cracked sealant and reapplying fresh sealant at flashing joints where the metal itself remains in good, serviceable condition.
Identifying chimney crown or cap issues found during flashing work that fall outside roofing scope and pointing you toward the right resource for those repairs.
Repairing the cut mortar joint that holds counter flashing in place against the chimney, which deteriorates over time and can loosen the flashing's seal.
We inspect all flashing layers — step, counter, and base — along with the mortar joint condition where counter flashing ties into the chimney.
Where there's an active leak, we confirm whether it's originating at the flashing itself or from a related chimney issue like crown cracking.
Failed or corroded flashing sections are removed carefully to avoid damaging surrounding shingles or the chimney's mortar joints.
New step, counter, and base flashing are installed and integrated with the surrounding roofing material, with counter flashing properly set into the mortar joint.
Appropriate sealant is applied at final joints where flashing pieces meet, providing an additional layer of protection alongside the mechanical flashing itself.
We verify all flashing layers are properly lapped and sealed, and confirm there's no remaining path for water to reach the chimney-to-roof junction.
Cost depends on whether the fix is a reseal or a full flashing replacement, chimney size, and roof pitch at the chimney's location. Mortar joint repair needed to properly reset counter flashing adds scope compared to a straightforward metal swap. We assess the flashing directly on-site to give you an accurate number.
Get an EstimateWe treat chimney flashing as a layered system rather than a single strip of metal, checking step, counter, and base flashing together along with the mortar joint condition. A repair that ignores one of those layers tends to leak again within a season or two.
Tell us about your home and we’ll come out, measure, and give you a written price with the scope spelled out. Prefer to talk it through? Call (631) 972-0873.
(631) 972-0873No obligation. We usually get back to you within one business day.