Fireplaces, chimneys and flues

6.8.5Solid fuel – flue pipes

Flue pipes shall be correctly designed to connect an appliance to a flue safely. Issues to be taken into account include:

  1. size, direction and jointing
  2. separation from combustible materials.

Size, direction and jointing

Flue pipes should have a cross-section which is equal to the outlet of the appliance they serve and should not be inclined more than 45° from vertical. A horizontal section no longer than 150mm may be used to connect a back outlet appliance to a flue. Socket joints should be fitted socket up.

Separation from combustible materials

Flue pipes should be separated from combustible materials in accordance with building regulations, and:

  • by a minimum 200mm of non-combustible material
  • by an air space which is a minimum of 4xD, or
  • be shielded by a non-combustible shield at least 4xD in width, and extended at least 1.5xD either side of the flue pipe; the shield should be at least 12mm from the combustible material, and the flue pipe at least 1.5xD from the combustible material.

(D = external diameter of the flue pipe)