Chimney Crown Repair and Replacement in Denver

Many crowns we see on Denver chimneys are not real crowns at all. They are a thin layer of mortar troweled over the top bricks, with no overhang to throw water clear and no gap where the flue tile passes through. Mortar like that shrinks, cracks and lets water in, and with about 135 freeze-thaw days a year, each crack grows a little every winter.

Hail adds its own damage. The Front Range sits near the heart of what forecasters call hail alley, and because the ground is so high, hail has less distance to fall and melts less on the way down, as a KOAA explainer put it. Chips and fresh cracks in a crown after a storm are common. Sealing cracks typically runs $600 to $1,000; a new poured crown $1,000 to $2,200.

Signs you need this

• Hairline or open cracks across the top of the chimney
• Chunks of concrete or mortar on the roof
• Water in the firebox after snow melts
• Dark, wet patches on the top courses of brick
• Flaking brick just below the crown

How we do it

1. Inspect the topWe photograph the crown, the flue tile and the top courses, and tell you whether sealing will hold or a new crown is needed.
2. Seal or removeSound crowns get cracks cleaned out and sealed with a flexible crown coating. Failed ones are broken out.
3. Pour a new crownFormed in place with an overhang and drip edge, and a gap around the flue tile so it can move with heat.
4. Cap itWe check the cap and replace it if needed, since a cap keeps rain and snow off the new crown and the flue.

Should I seal the crack or pour a new crown?

A well-built crown with only hairline cracks can take a flexible coating over its whole surface, which usually stops the water and is the cheaper route at $600 to $1,000. If the crown is a thin mortar wash, is broken into pieces, or has no overhang, a coating only buys time.

A new poured crown, typically $1,000 to $2,200, fixes the design. It sheds water past the face of the brick, and it is separated from the flue tile so heat movement does not crack it again.

Will a crown repair hold through hail season?

No crown is hail-proof, and we will not tell you otherwise. A properly poured crown with an overhang stands up to hail and frost far better than a mortar wash, and a coating can be chipped by a hard storm. After a big hailstorm it is worth having the top checked, and we photograph any new damage so you can show it to your insurance adjuster.

Why do crowns crack so often in Denver?

Because the top of the chimney goes through more temperature swings than any other part of the house. The sun heats it on a winter afternoon and it freezes again at night, roughly 135 times a year. Snow sits on it, especially in Boulder, which averages 92.8 inches a year. A small crack that would last years in a mild climate opens fast here.