Vent: a sweep in Buffalo told me to stop brushing flues top-down on old masonry, and I brushed him off for 3 years
After cracking the crown on a 1920s chimney in Allentown last month because I was forcing the brush from the roof, I finally looked at how he works from the cleanout with a shorter rod and realized he was right about the mortar being too soft for that kind of pressure, so has anyone else switched to bottom-up on pre-war brick?