What is a chimney?
A chimney (Dutch: schoorsteen) is the structure that carries smoke and flue gases from a fireplace, stove or boiler to the outside. In everyday speech, it often means just the part above the roof, which is more precisely called the chimney stack.
The Dutch word has several meanings:
- originally the masonry support (Dutch “schoor”) of the smoke hood above a hearth against a wall;
- the masonry flue above the hearth;
- the chimney breast or mantelpiece around the fire;
- the part of the flue projecting above the roof;
- a free-standing industrial chimney;
- nowadays also the housing on the roof for the outdoor unit of a heat pump.
History
For a long time, houses had no chimney: the fire lay on the floor and the smoke escaped through an opening in the roof. Later, smoke was led through timber flues daubed with clay. In the Netherlands, today’s form of the brick chimney became common from the mid-17th century.
Construction
A chimney consists of one or more flues (formerly brick, nowadays often lined with stainless steel or clay liners), the stack above the roof with lead flashings to make a watertight joint with the roof covering, and a top such as a capping slab, cowl or pot.
Application
Practical tips for use and maintenance:
- Sweeping: have chimneys serving open fires and wood burners swept and inspected regularly. Fire services commonly advise at least once a year for wood; soot deposits can catch fire.
- CO alarm: fit a carbon monoxide alarm in the room with the appliance, and smoke alarms on every floor.
- Old flues: don’t simply bring an old brick flue back into use. Have it inspected; a liner is often needed.
- Leaks: damp around a chimney is often caused by poor flashings, failed pointing or a missing cap.
- Disused chimneys: a chimney that is no longer used can be capped, but keep a small vent to prevent condensation in the flue.
- Removal: a chimney breast or stack may be structural or part of a fire separation. Get a structural engineer’s advice before removing it.
Related Terms
- Open fireplace
- Chimney cowl
- Chimney niche
- Clay flue pipe
- Chimney lead gutter
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