Expert stone chimney repair in Rosemont

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

How deep to rake out stone joints

The National Park Service's Preservation Brief 2 sets the raking depth at 2 to 2 and a half times the joint width as a minimum, so new mortar bonds and stays put. For stone masonry with wide joints, that can mean several inches.

Loose or crumbling mortar beyond that depth also comes out. The brief shows new mortar falling out of a joint that was not prepared deeply enough. We rake to a sound depth and show you the prepared joints before filling.

• At least 2 to 2 and a half times the joint width
• Deeper where mortar is loose
• Square back so new mortar locks in

Resetting a loose stone

A loose stone comes out carefully, by hand, without prying against its neighbors. The old mortar is cleaned off the stone's back and the bed it came from, down to sound material.

Then the stone goes back with fresh mortar filling the whole bed, pressed in until mortar squeezes out around its edges, and the joints are tooled to match. Before any of that, we find out why it loosened, since a reset over the same water problem will not hold.

• Removed by hand, neighbors protected
• Old mortar cleaned off stone and bed
• Reset with full mortar coverage
• Joints tooled to the existing profile

Veneer that bulges or pulls away

When a section of stone veneer bows outward or shows a gap at its top edge, the bond behind it has failed. The cause may be corroded lath, a thin scratch coat, poor mortar coverage or water trapped behind the stone.

Surface fixes do not reach any of those. With your approval, the loose section is removed, the backing is checked layer by layer and rebuilt as needed, and the stones are reset with full coverage. The findings explain what failed and why.

Branches and stone chimneys

Branches that rub against a chimney scrape stone faces and joints each time the wind moves them, and leaves and twigs build up on caps and in gutters beside the chimney.

We point out limbs that touch or overhang the chimney during the inspection. Trimming is usually a separate trade. Removing the rubbing contact protects the repair we make.