Chimney services, Portland metro
Chimney crown repair and replacement, the first place Portland rain gets in
We repair chimney crowns across the Portland metro: hairline cracks sealed with a flexible crown coat, a breaking crown patched, or a new crown poured with an overhang and a drip edge. You get photos of the slab before and after.
Updated
What you are seeing
A failing crown rarely shows itself from the yard, so these are the clues that bring a Portland homeowner to the phone.
- A wet smoke shelf or water in the firebox after a run of wet days, with the cap in place.
- Chunks of gray concrete in the gutter or on the roof below the chimney.
- Brick faces flaking off the top few courses while the brick lower down looks fine.
- White mineral streaks starting right under the crown and fading as they go down.
- Moss growing in a line across the top of the chimney where water sits.
What we do on a crown visit
Crown work is decided by what a probe and a hammer find on the roof, so the steps start with looking and end with a cure under cover.
Get on the roof and read the slab
The crown cannot be judged from the ground, so the first step is a safe ladder setup and a close look at the top of the chimney. We photograph the whole slab, then run a screwdriver along every crack and tap the surface for hollow spots where the concrete has separated from the brick beneath it.
Sort hairline cracks from a crown that is leaving
A crown with shrinkage cracks narrower than a credit card, solid when tapped and still tight to the tile, is a candidate for sealing. A crown with open cracks, loose chunks, a corner missing or no overhang at all is a candidate for patching or a new pour, and we say which before any work starts.
Clean and dry the surface
Moss, lichen and loose grit come off with a wire brush and a scraper, the cracks are opened a little so the filler can key in, and the slab is left to dry. In a Portland winter that can mean a tarp over the chimney for a day, because a coating or a patch put onto a wet crown peels by spring.
Seal the cracks and coat a sound crown
Cracks are filled with a flexible crown sealant that stays elastic as the slab moves with heat and frost, and the whole surface gets a brushed coat of a flexible crown product that bridges hairlines and sheds water. The coat runs out onto the top of the tile and down over the edge of the slab, where water would otherwise get behind it.
Form and pour a new crown when patching will not hold
A crown that is breaking up is chipped off down to sound brick, a form is built that projects past the brick on every side, and a new slab is poured from a mix made for the job, sloped away from the tile. A compressible wrap around the tile keeps the hot tile from cracking the fresh crown, and a groove under the overhang makes the drip edge.
Cure it, refit the cap and send the photos
Fresh concrete stays under a cover for a few days, and we come back to strip the form, seal the tile joint and set the cap. You get photos of the crown before, during and after, from the same spot on the roof, and the cap goes back on last so the first rain lands on a finished slab.
A crown or a mortar wash: what is on top of your chimney
A proper crown is a poured concrete slab a couple of inches thick that overhangs the brick on every side; a mortar wash is a thin bevel of mortar troweled flush with the brick, and some older Portland chimneys have only the wash.
A mortar wash cracks early, holds no overhang, and lets water run straight down the face of the brick. Sealing it buys a little time. The lasting fix is to chip it off and pour a real crown.
A true crown fails more slowly: shrinkage cracks first, then open cracks where the tile pushes against it, then spalled corners. Caught at the first stage, it is a coating job rather than a pour.
Which crown repair fits which damage
Hairline cracks in a solid crown get a crown coat, open cracks or a missing corner get a patch, and a crumbling crown or a mortar wash is poured new.
| What the crown looks like | The repair | What it buys |
|---|---|---|
| Hairline cracks, solid, tight to the brick | Flexible sealant in the cracks, crown coat over the whole slab | Dry brick without disturbing the cap or tile |
| Open cracks, a missing corner, a hollow spot | Chip out the loose material, patch with primed repair mortar, then coat | A sound slab again, at a fraction of a new pour |
| Crumbling, no overhang, a mortar wash, or separated from the tile | Remove and pour a new crown with overhang, drip edge and bond break | A crown built the way the chimney should have had from the start |
Why Portland leaks start at the crown
The crown is the one horizontal surface on a chimney, and in a city that sees about 37 inches of rain in a normal year, most of it between November and March, it stays wet for weeks at a stretch.
Add the roughly 32 nights a year that dip to freezing, nearly all of them inside those same wet months, and the water in each crack expands, widens it, and lets more in. By spring a hairline from October can be an open crack, and the brick under it can start to spall.
Water that gets through the crown runs down between the tile and the brick. It shows up as a wet smoke shelf, efflorescence on the top courses or a stain on the ceiling beside the chimney, and the crown is the first thing we check for all three.
What moves the price of crown repair
The board price is a crown coat over a sound crown or a patch on one that has started to break, so the list below is what pushes it higher.
- A crown that has to be chipped off and poured new, which is priced after we have seen and measured it.
- A mortar wash standing in for a crown, since there is nothing sound to coat and the job becomes a pour.
- Spalled top courses of brick that have to be replaced before a new crown has anything solid to sit on.
- A steep or tall roof that needs roof hooks or scaffold to work safely at the top of the stack.
When a repair stops making sense
A crown is poured new rather than patched when more than a corner is loose, when it has no overhang, when it is a mortar wash, or when it has broken its bond with the tile and rocks under a hand.
When the top courses of brick under the crown are spalled or the mortar between them has washed out, a new crown on its own is a lid on a failing wall. That chimney needs the top courses rebuilt first, and the crown is poured as the last step of that job.
Crown: common questions
When can a chimney crown be coated instead of poured new?
When the crown is still solid and the cracks are hairlines. Those get filled with a flexible sealant and the whole slab gets a brushed crown coat, which is the board price. A crown with loose chunks, a missing corner or no overhang is patched or poured new, because a coating cannot hold concrete together.
Is a chimney crown the same thing as a mortar wash?
No. A crown is a poured concrete slab, a couple of inches thick, that overhangs the brick and sheds water past the chimney face. A mortar wash is a thin slope of mortar troweled flush with the brick, with no overhang, and it cracks early. Some Portland chimneys have only a wash, and the lasting repair is to replace it with a real crown.
How do I know the chimney crown is why water is in my firebox?
Water from a crown runs down between the tile and the brick to the smoke shelf, so a wet shelf with a cap in place points up top. We confirm it on the roof with a probe and a hose test, checking cap, crown and flashing one at a time, so the repair goes to the real source.
Does chimney crown repair have to wait for dry weather in Portland?
The surface has to be dry when a coating or a patch goes on, and a new pour needs a few days above freezing to cure. In the wet months we work in dry windows and tarp the chimney between visits, so crown repair runs year round here, just with more care about timing between October and April.
Why does a new chimney crown need a gap around the flue tile?
The tile heats and grows when a fire burns, and a crown poured tight against it cracks the first time that happens. We wrap the tile with a compressible bond break before the pour and seal the joint afterward with a flexible sealant. The gap is a large part of why a well-built crown lasts while a tight one cracks early.
Will crown repair fix the white stains on my chimney brick?
It cuts off the water behind them when the crown is the entry point, which it often is when the staining starts right under the slab. Efflorescence that is already on the brick weathers off slowly or is brushed dry. If the white deposits run the full height of the chimney, the mortar joints and flashing get checked as well.
Related pages
Where we do this
We repair and pour chimney crowns throughout the areas below, from the tall stacks of the Southwest Hills to the ranch-house chimneys of Aloha and Oak Grove.
Ready to book a sweep?
Call with what the fireplace is doing, or text a photo of the opening and one of the chimney top, and we will name the service and its posted price before we come out.