Chimney crown repair · local climate
Why crowns work hard in the Puget Sound region
In the Puget Sound lowlands a crown’s main job is shedding rain, not carrying snow. At Sea-Tac Airport, NOAA’s 1991–2020 climate normals record only 6.3 inches of snow in a normal year, while about three quarters of annual precipitation falls from October through March. Crowns in the foothill and valley communities, which run colder and wetter than the airport, have a harder time of it.
SOURCE · NOAA NCEI CLIMATE NORMALS 1991–2020, STATION USW00024233
The station also normally accumulates 4,375.8 heating degree days a year, a sign of a long heating season. For a chimney in regular use, that means many rounds of the flue warming and cooling inside a crown that is often wet, one reason the flue joint matters as much as the slab.
Masonry soaks up some rain and dries afterward, and problems start when drying never catches up.
When to inspect the whole chimney first
The crown is assessed in the inspection that comes before any quote. Start with a broader chimney inspection if water shows up indoors, the top flue tile is cracked or has dropped, or the upper brick is loose or leaning. If the flue needs a new tile or relining, decide that before a new crown is cast. The crown is built around the flue.
Sealing, resurfacing or recasting
Sealing isolated cracks
A sound, well-shaped crown with a few narrow cracks can have them cleaned out and filled with flexible masonry sealant. It suits only a crown that already sheds water.
Resurfacing a sound crown
Where the slab is solid but crazed across its surface, loose material comes off and a flexible crown coating is built up. A coating renews the surface; it cannot add slope, overhang or a drip edge.
Recasting a failed crown
A crown that is broken through, delaminating or a worn-out mortar wash is removed to sound brick with the flue covered. A new reinforced slab is cast with a fall away from the flue on every side, an overhang and a drip in the underside.
What affects the cost of crown repair
The first question is which of the three repairs your crown needs. After that, these matter most.
- Seal, resurface or recast
- The three differ greatly in labor and material, and the crown’s condition and shape decide which applies.
- Size and number of flues
- A wider chimney means more slab, and each flue through the crown adds a joint to detail.
- Access
- Roof pitch, height and roofing affect how the top is reached and the old crown brought down.
- What is under the old crown
- Spalled brick or open joints found once it is off must be made sound first, priced separately and only with your approval.
- Cast in place or precast
- A cast crown needs forms and suitable curing weather; a precast slab is made to measure and set in place.
