Cracked chimney masonry repaired in Southern Oaks

Signs that point past routine masonry repair

Brick Industry Association Technical Note 46 lists conditions that are structural rather than routine maintenance, and says they generally warrant investigation by a professional engineer.

When we see any of them, we tell you before quoting a repair, because patching a crack that is caused by movement tends to crack again.

• Cracks wider than about 0.075 inch, or 2 mm
• Cracks that pass through several bricks
• Cracks that follow a stepped or diagonal pattern
• Widespread spalled brick
• Masonry that has moved out of plane

How we find weak joints

Weak mortar is not always obvious from a distance. Brick industry guidance describes visual observation and light scraping with a metal tool as common ways to find joints that need repointing.

We do exactly that on the faces we can reach, and we note where sound joints stop and soft ones begin. That boundary becomes the repair area in your estimate, so the estimate covers the joints that need work rather than an entire chimney by default.

Brackets, mounts and extra load

Section R1003.8 of the residential code limits a chimney to carrying its own weight unless it was designed and built for more.

Antenna brackets, satellite mounts and similar attachments bolted to masonry add load and leverage the chimney was not built for, and the fasteners can crack joints and brick. We recommend removing them as part of a masonry repair and filling the holes and damaged joints they leave. If an attachment is still needed, such as a cable run, we suggest a route that does not rely on the chimney.

The base and footing of the chimney

The bottom of an exterior chimney sits on a footing, and problems there show higher up as cracks or lean. Damp soil, poor drainage or plants against the base keep the lowest courses wet.

We look at the base as well as the top, noting cracks near grade, gaps from the wall and signs of settling. Movement at the base is a structural question, and we tell you when it calls for an engineer rather than a masonry repair.