Natural and cultured stone chimney repair in Beulah

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.

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

Two layers of barrier behind the lath

Behind the lath, the barrier matters most. The instructions we follow call for the water-resistive barrier to be installed as two separate layers, lapped shingle fashion so water runs down and out instead of in. The layers wrap continuously around inside and outside corners.

Where veneer has been removed for repair, we look at the barrier closely. Torn, missing or reverse-lapped barrier is replaced before new lath goes up. It is hidden work, and it is the work that keeps the framing behind a stone chase dry.

Cracks that step through the joints

A crack that steps up through the mortar joints of a stone chimney often follows movement, such as a settling footing, a shifting chimney base or a failing support where the chimney meets the house.

Repointing a moving crack only closes it for a while. We trace the crack, check the base and the chimney's connection to the wall and explain what is moving before recommending a repair. When the movement is serious, the findings say so plainly.

Spot repointing or the whole face

When a few joints have failed in an otherwise sound wall, spot repointing is sensible. The brief notes that spot repointing is generally preferable, with some color difference acceptable.

Where soft, eroded mortar spreads across a wide area, or old and new joints would clash, repointing an entire face finishes more evenly. We explain which your chimney needs and price both when the answer is close.