Our team completed a chimney crown rebuild on a home in Argyle. The crown is the concrete cap that covers the top of the chimney around the flue, and on this chimney it was past the point where sealing it again would hold, so we removed it and built a new one.
What a Chimney Crown Does
The crown is the roof of the chimney. It covers the masonry from the outer edge of the brick to the flue, and its only job is to shed rain away from the chimney. Once it cracks, water runs through the crack into the brick and mortar below, and the damage works its way down from the top: open mortar joints, spalling brick faces, and leaks that show up inside around the fireplace or the ceiling.
In North Texas, hail and the swing between wet and dry weather open small crown cracks quickly, which is why a crown that has already been patched often cracks through again.
How the New Crown Is Built
The old crown is broken out down to sound masonry and the top of the chimney is cleaned off. A form is set so the new crown overhangs the brick on every side, with a drip edge underneath so water falls clear of the chimney face instead of running down it.
The new crown is poured with a slope away from the flue so water cannot sit on top, and the joint at the flue tile is sealed with a flexible sealant. The tile and the crown expand at different rates, so a flexible joint keeps that movement from cracking the new crown.
