What are chimney corbels?
Often called “shoulder” or “hips”, chimney corbels are bump-outs or protrusions on a chimney, most often found near the smoke chamber of a chimney. The corbels will follow the contour of your smoke chamber, which is shaped like an upside-down funnel. Without these corbels, your chimney would be the same width from the bottom to the top, and there would be a lot of unnecessary space and materials used in the construction of your chimney.
Not all chimneys have corbels. Some have only 1. The thing that determines how many corbels your chimney has is typically related to how many flues your chimney has. For example, my chimney has a corbel only one 1 side, as I have a fireplace on the main floor, and another in the basement.
Corbels Need Special Care
Chimney corbels need to allow water to shed off the surface. They need to be sloped and smooth to do this. If your chimney was built with brick holes facing upward, they can retain water which will cause damage to your chimney after the freeze-thaw cycle. For these types of builds, we recommend having the corbels capped, whereby we put a concrete slab over the bricks, which allows water to run off without entering the bricks below.
If your corbels are stair-stepped but do not have the holes exposed, they are still at some risk because water will pool on any horizontal surfaces. For these, we can smoot out the stair-step with a mortar fill.
Even if your chimney is constructed in such a way so that the brick faces are sloping the water away, you will want your chimney sweep to inspect them annually to ensure water is not beginning to penetrate the mortar joints.
If your chimney has corbels, ask your sweep to let you know how it is doing during your next inspection.