Natural and cultured stone chimney repair in Winter Garden

Flashing where the stone starts and stops

The maker's instructions call for corrosion-resistant flashing or weep screed and a means of drainage at all penetrations and terminations of the stone cladding, with flashing type and locations following the applicable building code.

On a chimney, those edges include the roof line, the top under the cap and any trim transitions. Missing or failed flashing at an edge can explain water behind stone, so we check every edge on the chimney.

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

Curing fresh joints on a stone chimney

High-lime mortars harden as they lose water and take up carbon from the air, and drying too fast can leave them chalky and weak. Preservation Brief 2 describes misting repointed areas with a fine spray for a day or two and covering walls with burlap for the first three days, with any plastic tented away from the wall.

What we do depends on the mortar and the day. We protect new joints from hard rain and strong sun and leave you short notes on what to avoid while they cure.

Ledgestone and stacked courses

Ledgestone styles are laid in long, level courses, and one maker's directions say they should be installed from the bottom up, keeping each course level and plumb, with long pieces run horizontally.

A loose or missing piece breaks the line and is easy to spot. We reset pieces level with their neighbors, trim replacements to the course height and check alignment as we go, so the repair disappears into the pattern.

A yearly look at a stone chimney

NFPA 211 expects every chimney, fireplace and vent to be inspected yearly at the least. For a stone chimney, that yearly visit covers the flue and the stonework together.

We tap the stones, check the joints and look at the cap, flashing and base each time. Most years the answer is a routine note. The written record helps spot small changes early, before a loose stone becomes a missing one.