Chimney

A chimney is a tall hole that lets smoke out of a house. It is the only part of a building that is mostly not there: by volume a chimney is 97% air surrounded by 3% chimney, making it, structurally, a very tall nothing that some bricks have agreed to stand around.^[1]

Chimneys point upwards because smoke had already decided to go that way, and early builders saw no benefit in arguing with it.

Height

A chimney must be taller than the roof it comes out of. A chimney that is shorter than its roof is legally classified as a fireplace with ambitions.^[2]

Under the Flue Regulations of 1873, the height of a chimney is measured from the bottom of the chimney to the top of the chimney, after an earlier method, measuring from the top down, kept producing the same answer and was felt to be showing off.

Residents

Birds nest in chimneys because they are warm and high. From the bird's point of view a chimney is a pleasant tower that occasionally, and without consultation, becomes a much warmer tower.^[3]

Sweeping

Chimneys are cleaned by chimney sweeps, the only profession in which a thing is cleaned by transferring its dirt onto the person cleaning it. The exchange rate has been fixed at one sweep's worth of soot per chimney since records began, and has never been adjusted for inflation.

See also

• Brick – the 3%
• Lighthouse – a chimney that lets out light instead
• Lamppost – another tall thing outside
• Match – how the fire under it starts

References

1. Flue, F. (1999). Mostly Hollow. Upward Press. p. 97.
2. Parliament of Roofs (1873). "Flue Regulations". Section 1: Up.
3. Soot, S. (2011). "Warm, Then Very Warm". Avian Housing Review 4.