Chimney Repair & Rebuild

The crown. The crown is the sloped concrete or mortar wash on the very top of the chimney that sheds water away from the flue and the masonry below. A thin mortar crown (common on NJ chimneys built before the 1990s) cracks within a decade of freeze-thaw cycling, and water runs straight down into the masonry core. A cracked crown is one of the most common chimney leaks we find — and one of the most overlooked, because you can't see it from the ground.

The cap. The cap covers the flue opening. A missing or rusted-out cap lets rain straight down the flue (rotting the damper and staining the firebox) and lets birds, squirrels, and raccoons nest inside. A stainless multi-flue cap is cheap insurance and usually the first thing we recommend on an uncapped chimney.

The flashing. Step flashing under the shingles plus counter flashing cut into the mortar joint is the #1 chimney leak. Most older NJ chimneys were caulked instead of properly counter-flashed, and caulk fails at 5-7 years. (We cover the flashing rebuild in depth on our chimney flashing page.)

The brick and mortar. Spalled brick — where the face has popped off from absorbed water freezing — and deteriorated mortar joints wick water into the chimney and the wall below. Sealing over spalled brick doesn't fix it; the damaged brick has to be replaced and the joints repointed.

The cricket. NJ Uniform Construction Code (IRC R1003.20) requires a cricket — a small ridge that splits water around the chimney — behind any chimney 30 inches wide or wider. Many wide NJ chimneys never got one, and adding it solves chronic leaks where water piles up against the upper face.

A proper crown is not a thin smear of mortar. It's a sloped concrete wash, reinforced where it needs to be, with an overhang and a drip edge so water is thrown clear of the masonry, and an expansion joint around the flue tile so the crown doesn't crack as the flue heats and cools. When the existing crown is only cracked, a polymer-modified crown-coat repair can extend its life; when it's crumbling, we rebuild it.

Caps come in stainless single-flue, stainless multi-flue, and custom fabricated styles for oversized or historic chimneys. Stainless is the default — it doesn't rust like the galvanized caps that came on many older NJ homes. On a multi-flue chimney we fabricate or source a single cap that covers all flues plus the crown, which both keeps water out and protects the crown itself.

Why NJ weather is so hard on crowns and caps: the freeze-thaw cycle. Water gets into a hairline crown crack or behind a loose cap, freezes overnight, expands, and widens the gap a little more every cold snap. A crown that looks fine in October can be leaking by March. This is why we inspect the crown and cap on every chimney call, not just the flashing.

Repair scope (roof-side). Crown coat or rebuild, new cap, flashing rebuild, cricket, and waterproofing — this is the majority of chimney work and we do it directly. It solves the leak on a structurally sound chimney without the cost and disruption of a rebuild.

Partial rebuild (above the roofline). When the brick and mortar above the roofline have deteriorated badly — spalling, missing mortar, leaning — the section above the roof is rebuilt brick by brick. We coordinate this with our masonry partner and rebuild the crown, flashing, and cap as part of the same project so everything ties together.

Full / structural rebuild. When the chimney is structurally unsound below the roofline, it's a full masonry rebuild — coordinated with partner masons, sequenced so our roof-side work happens after the brick is sound.

Abandon and remove. For unused chimneys (converted to gas, or no longer venting anything), removing the chimney above the roofline and roofing over the opening is often the smartest long-term move — it eliminates the most common leak point on the house permanently. We'll give you the honest math on repair vs removal.