Family-owned stone chimney repair serving Catalina

The layers behind manufactured stone

On a wood-framed chase, one maker's instructions list the assembly in order, sheathing, two layers of water-resistive barrier, galvanized metal lath, a scratch coat, a mortar setting bed, the stone and the mortar joint. Each layer has a job, and a failure in one shows up in the stone.

When a section of veneer comes loose, we look at every layer behind it before resetting anything. Rebuilding the missing layer along with the stone is what makes the repair last.

• Sheathing on the framing
• Two layers of water-resistive barrier
• Metal lath and scratch coat
• Setting bed, stone and joint

Working in hot or dry weather

The same instructions say that in hot or dry weather, the back of each stone should be moistened with a fine spray or wet brush, and a concrete, masonry or scratch coat backing dampened before mortar goes on. Surfaces should look damp but carry no standing water.

Skipping that step lets the stone and backing pull water from the fresh mortar too quickly, weakening the bond. We plan the work and the dampening around the conditions on the day.

Roof flashing on a stone chimney

The line where a stone chimney meets the roof needs flashing built for it. The manufactured stone instructions we follow note that chimney or chase construction should incorporate proper flashing, and irregular natural stone makes the detail harder to get right.

Failed flashing can soak stones near the roof and the framing behind them. We check it from the roof, look for stains in the attic where it is accessible and list any flashing repair on its own line.

Stone faces that flake or spall

Spalling is when the outer face of a stone flakes or pops off. Moisture moving through the stone is usually involved, especially where hard mortar or a non-breathable coating keeps it from leaving through the joints.

Lightly spalled stones can stay if the cause is fixed. Badly damaged ones are replaced. Either way, the joints around them are repointed with a compatible mortar, and any coating that is trapping moisture is discussed before anything else is done.

Keeping people clear of loose stone

A stone that has loosened on a chimney can fall without warning, and even a small one can hurt someone below. Until the repair is done, keep people and pets away from the area under the chimney and do not pull on loose pieces.

When we arrive, the first job is making the area safe, securing or removing stones that are ready to fall. The permanent repair follows, with the removed stones cleaned and reset.