Natural and cultured stone chimney repair in New Malibu

What the code says about adhered stone veneer

Section R703.12 of the residential code covers adhered masonry veneer, the category manufactured stone falls into. It accepts the manufacturer's instructions as one installation route, and on framed walls it pairs the veneer with a water-resistive barrier plus a screed or flashing that resists corrosion at the foundation line.

In practice, that makes the maker's installation guide the working document for repairs too. We follow the guide for the stone on your chimney when one is known, and the general standard practice when the product cannot be identified.

ASTM C1780 and manufactured stone

ASTM C1780 is the standard practice for installation methods for adhered manufactured stone masonry veneer. Makers publish installation instructions written to comply with it, covering the backing, the barrier, the lath, the scratch coat, the setting bed, the joints and the cleaning.

When veneer fails, comparing what we find against those steps usually shows where the installation or a later repair went wrong. That comparison goes into the findings, so you understand the cause as well as the fix.

Cleaning manufactured stone the gentle way

Dirt on cast stone needs a light touch. The instructions we follow say it can be removed with granulated soap or detergent in water and a bristle brush, rinsed right away with fresh water. They rule out wire brushes, acid or acid-containing products, power washing and sandblasting.

Those methods can strip the colored surface of cast stone and leave marks that do not come out. We clean with the gentle method first and never reach for pressure or acid on manufactured stone.

• Detergent, water and a bristle brush
• Rinse right away with fresh water
• No wire brush, acid, pressure or blasting

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 chimney notes in a home inspection

Home inspection reports sometimes note loose stones, open joints, hollow veneer or missing drainage at the base of a stone chimney and recommend further evaluation.

We inspect the chimney, explain what each note means for that chimney and put the repair options and prices in writing. Buyers and sellers can read the same scope, which makes the conversation between them easier.