Repairing the flashing, counterflashing and masonry where a chimney or party-wall stack passes through a roof.
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Chimney flashing repair rebuilds the junction where a stack passes through a roof: step flashing up the sides, a saddle at the back, counterflashing into the brickwork, and sound masonry above it. It is the most common leak on a pitched roof. Call (833) 751-2102 for a local roofer.
A chimney is a wall standing in the middle of a roof with water running at it from above. The waterproofing is a set of overlapping pieces: flashing stepped up each side, a saddle or back gutter behind it, an apron at the front, and counterflashing let into the brick to cap the lot.
When any one of those is missing or has been replaced with sealant, the stack leaks. On older houses in this region it is also common to find the masonry itself is the route, through open joints, a cracked crown or spalled brick above the roof line.
Rowhouses add their own version. Party-wall stacks and old flues rise through or beside a shared parapet, so the flashing detail belongs to two houses, and a redundant flue that was capped badly is a classic source of water in a top-floor ceiling.
Because a flashing works by overlap and gravity, while sealant works by adhesion and has a much shorter life. A bead of mastic along the junction sheds water for a season or two, then cracks away from the brick and channels water into the gap it has created.
The giveaway on an inspection is a thick, repeatedly renewed smear along the junction with no metal visible underneath. That usually means the detail was never built properly, and each renewal has made the next proper repair a little harder.
A correctly formed detail has metal stepped up each side, let into the brickwork and capped, so water is always being directed out onto the covering rather than being asked to stay out by a glue. It costs more once and then stops being a problem.
Either, and on older stacks often both. A chimney stands fully exposed above the roof, so its mortar weathers faster than the rest of the house, and water entering open joints or a cracked crown runs down inside the masonry and emerges below. New flashing will not stop that.
The pattern helps: damp that follows wind-driven rain from one direction, or appears on a chimney breast well below roof level, points at the masonry. Water that arrives at the ceiling right beside the stack during ordinary rain points at the flashing.
With roughly four in ten city homes dating from before 1940 by an older Census-based analysis, there is a lot of old mortar standing above roof level in this region. Pointing the stack and repairing its crown is often the larger half of the job.
It still needs to be weathertight, and it is frequently the forgotten one. A disused flue collects rain, which soaks into the masonry and into the breast inside the house, and a crown or cap in poor condition makes it worse. Capping properly, with ventilation, is the usual answer.
Removing a stack below the roof line is another option, and that turns into a roofing job because the opening has to be closed up and made weathertight in the covering. It is a bigger scope than a flashing repair and may be a permit question.
Where a flue is still in use for an appliance, anything affecting it should be discussed with whoever services that appliance. The roof side of the work is the flashing, the crown and the cap; what happens inside the flue is a separate trade.
Flashing repair is normally maintenance. Rebuilding or removing a stack is structural work and a different conversation with Licenses and Inspections, or with the township, borough or New Jersey municipality outside the city. On a designated property, work visible from the street may also need Historical Commission review.
Chimneys are conspicuous by nature, which is why designation matters here more than for a hidden flat roof. The Commission's guidance favours work that is inconspicuous from the public right-of-way, and it confirms what applies to a particular address.
Scope is what decides the filing, so describe the work accurately when you ask: new flashing and pointing is not the same application as taking two feet off a stack. Our guide on roof permits in Philadelphia explains how it is filed.
Chimney work is high, exposed work beside a structure that may be less stable than it looks. Older stacks can be loose at the crown, and a brick coming off a chimney above a pavement is a danger to people below as well as to the roof. Do not climb to inspect it, do not lean a ladder against a stack, and do not attempt pointing from a ladder at that height. If you can see displaced brick or a cracked crown, keep the area below clear and get it looked at. Call (833) 751-2102 and have the stack assessed from proper access.
The roofer separates three possibilities: the flashing detail, the masonry of the stack, or the flue itself. They look similar inside the house and they need three different repairs, so the trace comes before the quote.
The crown, the joints, the brick faces and any cap are examined, along with how the existing flashing has been formed. Sealant doing the job of a counterflashing is the single most common finding on an older repair.
Water collects behind a stack, so the saddle or back gutter there takes the heaviest load. Wide chimneys on a slope may need a cricket to divert water around them, and its absence is often why the back keeps leaking.
Flashing fixes into sound brick and mortar. Open joints are repointed, a failed crown is repaired and spalled faces are addressed before new metal goes in, because counterflashing let into crumbling mortar will not hold.
Step flashing is formed up each side and woven into the courses, the apron and the saddle are renewed, and the counterflashing caps the upstands into the brick. Then the slates or shingles around it go back properly rather than being sealed down.
The classic arrangement on twins and suburban houses, with step flashing up both sides, an apron in front and a saddle behind. Repairs here are a defined piece of work and usually transform a roof that has leaked for years.
A stack rising through or beside a shared parapet on an attached house, where the flashing detail is shared with the neighbour. Sealing it properly on both sides matters for the same reason the rest of the party-wall termination does.
Older houses here are full of flues nobody uses. A stack capped with a slab, a sheet or nothing at all collects water and sends it down inside the masonry, which appears as damp on a chimney breast with the roof covering intact.
Most chimney flashing repair calls are scheduled the same day when a technician is free, and you approve the price before any work starts.
Chimneys are everywhere in the older stock, which is most of it. Stone houses and Victorian twins in Germantown, Mount Airy, Chestnut Hill and along the Main Line typically have more than one stack, often wide ones on a slope where the back gutter does the hardest work.
On attached houses the stack becomes a shared detail. Party-wall stacks and old flues through parapets in the city rows mean the flashing has a neighbour on the other side of it, and a leak can present in either house.
Wind-driven rain is what exposes a poor stack detail here. The Weather Service has documented tropical-storm gusts and microbursts of 60 to 70 mph across parts of the city, and rain driven sideways finds open mortar joints on the windward face of a chimney that vertical rain never reaches.
Repairing slate slopes on older stone houses, Victorian twins and historic-district properties, repair-first and with non-ferrous fixings.
Slope repairs, replacement courses and flashing work on pitched asphalt roofs across the suburbs and the twin-house neighbourhoods.
Tracing a leak to its actual entry point on flat or pitched roofs, then repairing the detail that failed.
A documented look at the roof, its drainage and its details before you buy, after a storm, or before you commit to work.
Not sure if you're covered? Check your ZIP code.
Historic slate in Philadelphia should be repaired rather than replaced whenever possible, according to National Park Service guidance.
Because wind decides which face of the stack gets wet. Driving rain from one direction loads open joints or a flashing edge on that side, so a chimney can stay dry through ordinary rain and leak every time the wind comes from the same quarter.
It diverts water around a chimney rather than letting it pile up behind the stack. On a wide chimney on a slope the back is the heaviest-loaded part of the detail, and the absence of a saddle is a common reason the back keeps leaking.
Partly, but the covering around the stack usually has to be lifted so the new metal can be woven in and the counterflashing let into the brick. On a slate roof that work needs care, which is why it goes in alongside slate repair.
It is a reasonable option for a stack that is redundant and in poor condition, and it removes a maintenance item. It is also a bigger job than a flashing repair, needs the roof closed up properly, and may be a permit and review question.
On a disused flue it keeps rain out of masonry that will otherwise stay damp, which is worth a lot. It should still allow some ventilation, and on a live flue anything fitted has to suit the appliance below it.
Possibly, via the masonry rather than the covering. Water entering open joints or an unprotected crown travels down inside the stack and shows up well below the roof, so the stack and the flashing are both inspected before anything is repaired.