Repair and resealing of chimney flashing and counter-flashing, the metal that keeps water out where a chimney meets the roof.
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Chimney flashing is the metal and sealant that joins a chimney to the roof, and counter-flashing is the piece set into the masonry above it. When either loosens or the sealant fails, rain and meltwater can run behind it and into the framing. A technician checks, repairs or replaces the flashing and confirms the joint.
Where a chimney meets a roof, the covering has to be joined to a vertical wall of masonry without letting water into the gap. Flashing does that job. Step flashing is laid in pieces up the slope against the chimney, each piece lapping over the shingle below and under the one above. Counter-flashing is set into a groove or a mortar joint in the masonry, and it laps down over the base flashing so that water runs off the metal rather than in behind it.
The Palouse adds snow and ice to that job. Snow sits on the roof around a chimney, and the chimney creates a roof offset, the point where one part of the roof rises against a vertical wall. The City of Moscow's amended building code asks designers to consider snow buildup at roof offsets, valleys and parapets, because drifting and sliding snow concentrate load there. The same spot collects meltwater after a thaw.
Masonry and metal do not move together. Brick, mortar, metal and sealant expand and contract at different rates as the temperature changes, and the joint between them is the part that gives first. A chimney that has been through many cold nights and warm days will show that movement as cracked sealant, a lifted counter-flashing edge or a gap in the mortar. A technician reads those signs before deciding whether the flashing needs resealing, replacing or a repair to the masonry itself.
Do not work on a chimney cap, crown or flashing from a ladder leaning against the masonry, because brick and mortar can break under a load. Do not use a torch or heat gun near sealant or roofing material. If the chimney serves a fireplace or a heating appliance and you see soot, staining or a smell, stop using it and have it inspected before anything else. Keep ladders on firm ground and away from the chimney when the roof is wet or frosted.
When the metal is sound but the sealant at the mortar joint has dried or split, the counter-flashing can be reset and resealed. It is a targeted repair, and it applies where the chimney masonry is intact and the base flashing is still tight. The crew checks the joint after resealing, because a seal that never bonded properly will fail in the first hard freeze.
Step pieces along the slope against the chimney can bend, rust through or pull away. When one or more are damaged, the pieces are replaced and woven back into the shingle courses. It is the usual fix when a leak is traced to the sloped sides of the chimney rather than the top.
Cracks in the cap or crown let water into the masonry, and water inside masonry freezes and expands. The repair is often done by a mason, and the crew coordinates it with the flashing work so that the metal is set after the masonry is sound. The crew explains whose work is which before anything starts.
Most chimney flashing repair calls are scheduled the same day when a technician is free, and you approve the price before any work starts.
Flashing fails when the sealant ages, the metal corrodes or bends, or the masonry moves and opens the joint. Each failure lets water run down behind the metal.
Sealant is the most visible part and the most likely to fail first. Exposed to sun and weather, it dries, shrinks and splits, and the gap it leaves lets water behind the metal. Sealant is a maintenance material, and it should not be the only seal over the long term, because the metal and masonry it bonds to are also moving.
Chimney flashing has to shed water from a vertical wall onto the roof, while valley flashing carries running water from two roof planes into one channel. The two are built and repaired differently.
Chimney flashing is layered, with step pieces that lap over the shingles below and counter-flashing that laps down over them. The layers have to be installed in order so that water always runs out and never in. A valley is a channel, built to carry a steady flow of water and snow down the roof.
Rarely. Sealant can hold a sound joint closed, but it cannot correct metal that is bent, rusted or pulled away from the masonry.
A bead of sealant over a lifted counter-flashing may stop the drip for a time, but the water is still running behind the metal. Sealant also does not bond well to a surface that is dirty, cold or moving. A crew uses sealant as a finishing step, after the metal and the masonry have been put right.
A chimney creates a roof offset, and snow and meltwater gather where the roof meets the vertical wall. The City of Moscow's amended building code asks designers to consider snow buildup at roof offsets.
The wall rises above the roof plane and catches drifting snow on its windward side. Snow that slides down the roof stops against it and builds up on the downhill side. After a thaw, meltwater runs toward the wall and the flashing, and a refreeze can hold it there. This is the same mechanism that concentrates load at valleys and parapets, and it is why the flashing takes more stress than the covering around it.
Height, pitch, the condition of the masonry, the number of pieces to replace and access decide most of the cost. The price is explained and approved before work starts.
A single counter-flashing reset on a low, easy chimney is a short job. A tall chimney on a steep roof, or one with several failed pieces and masonry repair, takes more time, more setup and sometimes a mason. Each of these factors is written into the estimate so the homeowner can see what drives the number.
A technician looks at the counter-flashing where it meets the masonry, the base flashing on the roof, the cap and the crown. The attic side is checked for staining on the chimney wall and the framing beside it. Together those views show where water is entering, which is not always where the stain appears in the house.
The mortar joints, the cap and the crown are checked for cracks and crumbling. Masonry repair is often a job for a mason, and the crew says so when the problem is in the brick rather than the metal. Sealant alone cannot repair cracked masonry, so that decision is made before any sealant goes on.
Counter-flashing is eased out of its groove or joint carefully, so the mortar and metal are not broken further. The base flashing and the step pieces beneath are inspected for bends, corrosion and nail heads that have pushed through. Any piece that is bent or rusted through is marked for replacement rather than straightened.
Sound metal is reset and resealed, and damaged pieces are replaced in an order that keeps water shedding over each layer. Step flashing is woven into the shingle courses so that no seam sits where water runs. Counter-flashing is set back into the masonry, and sealant is used as a secondary measure rather than the main seal.
After the work, the crew checks the joint from the roof and from the attic, looking for fresh wet spots and for any gap that was missed. The homeowner is shown what was replaced and what was resealed, and what to watch for after the next freeze and thaw.
The eastern towns on the Palouse plateau hold snow on their roofs longer than the lower river towns. Troy and Deary sit higher than Moscow's city center, and a chimney on those roofs faces snow that can stay into the spring. The river towns along the Snake River valley sit far lower, so the same chimney there sees less lingering snow. The flashing is detailed for the snow the roof actually holds, and the Troy area page describes that side of the map.
Moscow's Fort Russell district includes century-old houses, and the Fort Russell and Downtown districts are on the National Register of Historic Places. A National Register listing records historic significance, and the Community Development department confirms whether a particular property sits in a district with design review. Repairing flashing does not change the chimney's shape, but ask before any masonry work that would alter it.
Pullman is a university town in Washington, 14.0 kilometers from Moscow, with its own building department and permit portal. A flashing repair on a Pullman house is a job under Washington's contractor registration rules, and a repair on the Moscow side falls under Idaho's. Ask the building department whether a flashing repair alone needs a permit, because each office sets its own rules.
Not sure if you're covered? Check your ZIP code.
Resetting or replacing the metal at valleys, chimneys, sidewalls and vent pipes that keeps water out of a Moscow roof.
Finding and sealing the path water takes into your Moscow or Palouse home, from attic stains to flashing at the eave.
A look at the roof, gutters and attic before the first snow, to find the loose flashing and blocked gutter that cause winter leaks.
Air sealing and ventilation that keep attic heat from melting snow on a Moscow roof and feeding ice dams at the eave.
A new roof in Moscow is priced from the roof itself.
Look for staining on the ceiling or wall beside the chimney, rust or corrosion on the metal, and sealant that is cracked or missing. Check the attic for water stains on the chimney wall and the framing near it. A leak often appears far from its source because water runs along the roof structure, so the stain may not be directly under the chimney. A crew can trace the water path.
A homeowner can clean and inspect the area from the ground, but walking the roof to apply sealant is risky, and sealant alone rarely fixes damaged metal. A crew checks the metal and the masonry first, then reseals only where a sound surface remains. Sealing over a loose counter-flashing can hide a problem that keeps growing behind the metal.
Winter adds snow, ice and meltwater, and a freeze-thaw cycle that works the joint and the sealant. A gap that stays dry in summer can take in meltwater once snow sits against the chimney. The leak may appear only after a thaw, when water runs down the chimney wall. The crew checks the joint in the season the leak appears and in the other seasons too.
It is often related, because a cracked cap lets water into the masonry, and that water can run down to the flashing. The cap is masonry work, and a mason may be needed. The crew explains which part of the repair is roofing and which is masonry, and it coordinates the two so that the metal is set after the masonry is sound.
The rules depend on the city or county where the house sits. Moscow's Building Safety Division and Pullman's permit portal set their own requirements, and a flashing repair alone may or may not need a permit under them. Ask the building department before the work starts, and ask the crew to explain which permit applies to the job.
The timing depends on the weather, the crew's schedule and whether masonry work is needed. In winter the work is harder because of snow and ice, so a temporary cover may be used until the metal can be set. No date is promised, and the crew explains the plan when the visit is booked.