The Most Important Part You've Never Looked At
The crown is the slab on top of your chimney that seals the gap between the flue and the brick. It's your chimney's roof — and on most homes in Charles County, it's a thin layer of mortar troweled flat 20 or 30 years ago. Flat mortar crowns crack within a few years. Every crack is a direct path for rainwater into the core of your chimney, where it saturates the masonry from the inside out.
When we inspect chimneys, the crown is one of the first things we check — because a failed crown is behind an enormous share of the water damage we get called to fix.
Repair vs. Rebuild
Repair works when the crown is mostly sound with minor cracking: we seal the cracks with a flexible crown sealant designed for the job (not hardware-store caulk) and verify the drainage still works. This buys years on a crown that's fundamentally okay.
Rebuild is the answer when the crown is extensively cracked, crumbling, or was never more than a mortar wash to begin with. We remove the old crown and pour a proper one: minimum 2 inches thick at the edges, 4 inches at the flue, sloped to shed water, with a drip edge — a groove underneath the overhang that stops water from running back onto the brick face. We use concrete, not mortar, with the right mix for freeze-thaw exposure.
What a Proper Crown Looks Like
- Sloped, not flat. Water should run off, not pond. A proper crown slopes away from the flue in every direction.
- Drip edge. The crown overhangs the brick slightly with a groove underneath. Without it, water sheets down the brick face and soaks in.
- Expansion gap at the flue. The flue gets hot and moves; the crown doesn't. A flexible gap between them prevents the flue from cracking the crown every heating season.
- Concrete, not mortar. Mortar is for joints. Crowns need concrete's strength and weather resistance.
The Crown-Cap Combination
A new crown plus a stainless cap is the best top-of-chimney protection you can buy. The crown seals the masonry; the cap keeps rain out of the flue and animals out of the chimney. Together they address the two main ways water gets in from above. We recommend both on every crown rebuild.
Send the form — if you can safely photograph the top of your chimney, great; if not, we'll check it during the inspection.