Cracked chimney masonry repaired in Pine Castle

Fireblocking where the chimney passes floors

Section R1003.19 of the residential code calls for the spaces between a chimney and the floors and ceilings it passes through to be fireblocked with noncombustible material, securely fastened in place.

It is easy to overlook because it is hidden. When the attic or a ceiling opening lets us see it, we note what is there, and missing or combustible material is written up as a separate finding with its own recommendation. It sits outside the masonry repair itself, but it is part of the same chimney, and we would rather you know about it.

Rust on steel supports in the masonry

Accumulated rust on steel lintels or shelf angles is one of the conditions brick industry guidance lists as possibly structural. Rusting steel expands and can crack the masonry around it.

Where a chimney has steel supporting masonry, such as over an opening or at a change in width, we check it for rust and cracking. When the steel itself is failing, we say so plainly and explain whether an engineer's evaluation should come before the masonry repair. Replacing or treating that steel is a separate decision from the masonry around it, and the estimate keeps the two apart.

Why we avoid high-pressure washing

High-pressure water can erode soft brick faces and drive water deep into open joints. On a chimney that already has damaged masonry, it can make the problem worse.

When cleaning is part of the job, we look at the brick and joints first and choose the gentlest method that works, often low-pressure water and a brush. If a cleaning product is needed, it is one made for brickwork and used to its instructions. Water forced into open joints can also end up inside the house, which is a poor way to start a masonry repair.

Questions worth asking before you approve masonry work

A sound masonry proposal should answer each of these clearly. If one gets a vague answer, ask again, since each affects how the repair performs and what it includes.

• What is causing the damage, and is it fixed by this repair?
• Where exactly does the repair area start and stop?
• Which mortar type is proposed, and why?
• How close will the brick and mortar match be?
• What happens if more damage turns up?
• Which separate repairs, if any, are recommended?