Family-owned chimney repair serving Bel Air

Hairline cracks in a concrete crown

Fine cracks in a concrete crown do not always mean it was built badly. BIA guidance on chimney construction calls shrinkage of concrete as it cures a certainty, and it recommends reinforcement in a cast crown to help control cracking from shrinkage and from heating and cooling.

What matters is what the cracks let through. A few fine lines in a crown with a good slope and sound edges are a different case from cracks that cross the full width, reach the flue liner or have let water stain the brick underneath. The first is a small repair. The second can mean water is reaching the masonry, and the crown may need replacing rather than patching.

Width, length and pattern are all checked, along with the brick directly below. The estimate names one of the two options and sends the work to our chimney crown repair service, with the reasoning written beside it.

Overhang and drip edge keep water off the faces

Rain leaving a chimney top has to fall clear of the brick, or it runs down the faces and soaks in. BIA guidance shows the cap overhanging the faces. Where a cap does not overhang, it calls for the last two courses of brick to be corbeled out to form a drip, to help reduce the water running down the face.

A drip edge is also required by the Florida Building Code on the cap of a masonry chimney. The drip is simply the edge that water falls from, set out beyond the brick so the water drops free instead of creeping back to the masonry.

You can often read a missing drip from the ground. Streaks, dark wet patches or white deposits that start just under the top and spread down the faces can point to water leaving the top the wrong way. A flush top with those marks gets its own estimate line for a cap that overhangs.

Rust streaks running down the chimney

Orange or brown streaks down a chimney come from steel above them. They start under a rusting cap, a spark screen, a metal chase top or another steel part at the top, and they grow each time rain runs over the metal.

Rust on a part at the top of a chimney means that part is not standing up to the water it sees. BIA guidance says a metal rain cap should be corrosion resistant, and flashing is expected to be corrosion-resistant sheet metal for the same reason. A part that rusts through lets water in as well as staining the brick.

The fix starts at the source. Each streak is traced up to the part that made it, that part is replaced with corrosion-resistant metal and the stain is treated as a cleaning item for after the repair. On homes in Bel Air, the estimate names the rusting part first and the stain second.

Broken and spalled brick faces

Spalling is when the face of a brick breaks away and leaves a rough, recessed surface behind. BIA maintenance guidance notes that water gets through broken or badly spalled brick, and that the damaged units may have to be replaced.

Replacing a brick without finding out why it spalled only sets up the next one, so the joints, the top and the flashing around the damage are checked first. Our chimney brick replacement service handles the work, and on your Bel Air home the estimate lists the bricks to be replaced along with the cause they point to.

• The damaged brick is broken out to make removal easier
• Mortar around the opening is cut away without harming the neighbors
• New brick and the opening are fully buttered and the brick pressed in
• Joints are pointed and tooled to match the original profile