Fireplaces, chimneys and flues

6.8.20All – flue pipes

Flue pipes and terminals shall be suitable for their purpose and provide unrestricted passage for combustion gases between the fireplace, or appliance, and the outlet.

The connection between a fireplace, or appliance, and the flue should be correctly constructed.

Where the bottom of the flue is not directly over an appliance, it should be provided with a means of access for cleaning and inspection.

Adjustable flue draught control units are not permitted where gas burning appliances are installed. Where adjustable throat units are specified, they should be fitted in accordance with the manufacturer’s instructions.

Flue pipes should be jointed in accordance with the manufacturer’s instructions, fixed socket up and correctly aligned.

Table 9: Acceptable standards for flue pipes

Flue materialGuidance
Flue pipes for gas appliancesBS EN 1856
Cast iron flue pipesBS EN 1856
Mild steel flue pipesBS 1449 (minimum 3mm wall thickness)
Stainless steel flue pipesBS EN 10088 (minimum 1mm thick) and be one of the following grades: 1.4401, 1.4404, 1.4432 or 1.4436
Vitreous enamelled flue pipesBS EN 1856, low carbon steel coated internally and externally with acid-resisting enamel