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Chimney with cowel

Flues and chimneys

A flue is a duct, pipe or chimney for conveying exhaust gases from a wood fuel boiler to the outdoors. All wood fuel heating systems will require a flue.

In some circumstances it may be possible to line an existing chimney, for example: by inserting a flexible stainless steel flue liner manufactured specifically for solid fuel use; using a pumped refractory concrete lining; or adding a clay or concrete liner to the brickwork.

Where a chimney isn't available, a convenient method of constructing one is to use prefabricated, insulated, twin wall chimney components.

Flues must comply with building regulations. The technical handbooks for domestic and non-domestic properties specify various requirements for flues for solid fuel appliances.

Most new chimneys and flues will require a building warrant.

Under recent legislation for renewables in domestic properties, planning permission is not required for wood fuel generation under 45 kW unless:

  • the flue exceeds 1m above the roof height (excluding the chimney) installed on the principal elevation and visible from a road in buildings in Conservation Areas and World Heritage Sites.
  • the flue is situated within an Air Quality Management Area.

Publications to download

The Biomass Energy Centre have produced useful guides which contain information about flues and chimneys: