I received a quote to repair my chimney from a company and it mentioned "corbel top course". What does that mean?
Answer
A corbel top course is the top row of bricks on a chimney that steps outward slightly instead of staying flush with the rest of the chimney.
It serves as a drip edge so those bricks stick out farther then the rest of the chimney below so when rain & melted snow rolls off the chimney crown the water doesn’t run immediately down the side the rest of the chimney but rather drips off the edge of the corbel course away from the chimney. That seemingly small difference on the top row of bricks being layed farther out than the rest of the chimney provides long term results because it keeps water from constantly running straight down the the side of rest of your chimney which will wear the bricks faster over time.
