Residential chimneys are rarely over fifty feet tall and they are supported at every floor and roof line.
Taller is better because a taller chimney provides a greater accumulated pressure differential due to the taller column of warm air inside the flue, each cubic foot of which is lighter than a cubic foot of cooler ambient air. Add them up. A 20 foot tall chimney draws twice as well as a ten foot tall chimney. There is no maximum chimney height mentioned in the ICC codes or in the referenced ASTM C1283 standard. I am a member of the ASTM C4 committee which developed ASTM C 1283 and I remember that we discussed the issue of limiting chimney height but none of the engineers on the committee thought it was necessary since residential chimneys are rarely over fifty feet tall and they are supported at every floor and roof line - well within engineering standards - and taller chimneys are usually part of commercial buildings which are designed by engineers. The chimneys in houses built many decades ago were built with different requirements than today’s, which sometimes means that safety is a real concern. Any chimneys built prior to the 1950s were almost certainly masonry or block chimneys. The most common problem with old houses is that the chimneys aren’t lined, since that wasn’t a requirement when the fireplace was built. Bricks that were made in the 1600s and 1700s were of a much better quality than today’s bricks, chiefly because of the method used for firing them. In spite of their incredible durability, there comes a time with every chimney when the mortar wears out. If the damaged mortar in a chimney is not replaced, the chimney will begin to lean and will ultimately collapse. Fortunately, there is a procedure called “tuckpointing” which makes it possible to simply remove old mortar and replace it with new. No tearing down or rebuilding is required, if you catch the problem in time. Tuckpointing will restore the original shape of the chimney and strengthen the entire structure giving it a fresh look.
Size: 3456px × 5184px
Location: Surry England
Photo credit: © Steve Welsh / Alamy / Afripics
License: Licensed
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