Fire place walls to consist of non combustible material of at least 200mm in thickness to the side 100mm thick in the back wall recess, lined with suitable fire bricks. The hearth to be at least 125mm thickness (or 12mm thick if provided over a concrete floor slab) of non
combustible materials with projections at least 150mm to the sides of the side jambs and 500mm in front of the jambs.
Free standing stove with hearth
Free standing stoves & hearths to be positioned 150mm minimum away from enclosing non combustible walls at least 100mm thick. Hearths to be at least 125mm thickness (or 12mm thick if provided over a 100mm thick concrete floor slab),constructed of non combustible materials with projections at least 150mm to the sides & rear of the appliance and 300mm in front of the appliance door.
Air supply (ventilation) to solid fuel appliances
Permanently open combustion air vents ducted to outside are to be provided in the same room as the solid fuel appliance with a total free area in compliance with the table below (see Table 1 of ADJ for further information)
Table 22: Air supply (ventilation) to solid fuel appliances
Type of appliance Amount of ventilation
Open fire place with no throat (i.e. under a Canopy)
Open fire place with throat
or for simple fire openings:
500mm wide 450mm wide
400mm wide 350mm wide
50% of the cross section area of the Flue
50% of the cross section area of the Throat opening area
20,500mm2 18,500mm2 16,500mm2 14,500mm2 Enclosed stove with flue draught stabilizer
In new extension (good air tightness) In existing building (if air tightness
improved- use figure for new extension)
850mm2/kW of appliance rated out put 300mm2/kW for first 5kW & 850mm2/ kW of balance of appliance rated out put
Enclosed stove with no flue draught stabilizer
In new extension (good air tightness) In existing building (if air tightness improved- use figure for new extension)
550mm2/kW of appliance rated out put 550mm2/kW for appliance rated out put Above 5kW
Carbon monoxide alarms
Mains operated carbon monoxide alarm is required at ceiling level in the same room as the solid fuel appliance, which must be either battery operated in compliance with BS EN 5029: 2001: or mains operated with sensor failure warning device in compliance with BS EN 5029: Type A
Carbon monoxide alarm to be positioned on the ceiling at least 300mm from walls, or if located on the wall as high up as possible (above any doors or windows) but not within 150mm of the ceiling, and between 1m and 3m horizontally from the appliance
Table 23: Sizes of flues in chimneys
Installation Minimum internal flue sizes
Fire place with opening up to 500 x 500mm 200mm (diameter, rectangular or square) Fire place with opening more than 500 x
500mm or exposed on both sides
Area equal to 15% of the total face area of the fireplace opening. (note: total face areas more than 15% or 0.12m2 to be designed by heating specialist) Closed appliances* (stove, cooker, room
heater & boiler) up to 30kW rated output 30- 50kW rated output
(diameter, rectangular or square) 150mm
175mm Closed appliances up to 20kW rated output
which-burns smokeless/low-volatile fuel, or complies to the Clean Air Act
See table 2 of ADJ
Pellet burner which compiles to the Clean Air Act
Construction of masonry chimneys
Chimneys to be constructed in external quality frost resistant materials 100mm minimum
thickness (increased to 200mm where separates another fire compartment or another dwelling), using brick, dense blocks or reconstituted/natural stone to match the existing, with suitable mortar joints for the masonry as the masonry manufacturers details with any combustible material kept at least 50mm away from the walls containing flues.
Line chimney with manufactured flue liners installed in compliance with manufacturers details as follows:
(i) Clay flue liners to BS EN 1457:2009: Class A1 N1 or Class A1 N2, to be laid vertically and continuously socket up (jointed with fire proof mortar) from appliance with a minimum diameter in compliance with table 22
(ii) Concrete flue liners to BS EN 1857:2003: Type A1, A2, B1 or B2 to be laid vertically and continuously socket up (jointed with fire proof mortar) from appliance with a minimum diameter in compliance with table 22
(iii) Liners whose performance complies to BS EN 1443:2003: designation: T400 N2 D 3 G with a minimum diameter in compliance with table 22
Backfill gaps between masonry and flue liners with a weak mix concrete using 1:6 ordinary Portland cement and vermiculite. Build in code 5 lead flashings (including apron & lay board flashings) & dpc tray into chimney as work proceeds, 150mm above all roof/wall abutments as necessary & terminate chimney with a proprietary chimney pot to match the internal flue sizes.
Construction of factory made flue block chimneys
Construction of factory made flue block chimneys are to be carried out in compliance with paragraphs 1.29 – 1.30 of ADJ, and appliance manufacturer’s details.
Construction of factory made metal chimneys
Construction of factory made metal chimneys are to be carried out in compliance with paragraphs 1.42 – 1.46 of ADJ, and appliance manufacturer’s details. Factory made metal chimneys are to be concealed in the building in compliance with paragraph 1.47 & diagrams 13 & 14 of ADJ.
Configuration of flues serving open flue appliances
Flues to be constructed straight and vertical with no more than a 90 degree bend with cleaning access where the flue connects to the appliance and no more than two 45 degree bends (to the vertical) in the flue configuration in compliance with paragraph 1.48- 1.49 of ADJ, .
Inspection & cleaning openings in flues
Inspection & cleaning openings should be air tight using proprietary factory made components compatible with the flue system, fitted & located to allow sweeping of the flue in compliance with appliance manufacturers details
Interaction of mechanical extract vents & opened flue solid fuel appliances
Where a kitchen contains an opened flue- solid fuel appliance, confirm extract
ventilation will not be installed in the same room as the appliance, or alternatively seek further guidance from HETAS.
Chimney heights
Chimney height not to exceed 4.5 times its narrowest thickness. Chimney/terminal to discharge at a minimum height of:
1.0m above flat roofs
1.0m above opening windows or roof lights in the roof surface
0.6m above the ridge
Outside of a zone measured 2.3m horizontally from the roof slope
0.6m above an adjoining or adjacent building that is within 2.3m measured horizontally (whether or not beyond the boundary)
Please refer to Diagram 17 of ADJ for full details
Alternative heating producing appliances as detailed on the drawing/specification to be in compliance with ADJ.
Repair/relining of existing flues
Repair /relining of existing flues to be carried out by a suitably qualified and experienced specialist. Re-use of existing flues to be inspected, tested and certified by a suitably qualified and experienced specialist prior to use as suitable for solid fuel appliances.
Relining of existing flues to be carried out in compliance with BS EN 1443:2003: designation: T400 N2 D 3 G with minimum diameters in compliance with table 22 using lining systems suitable for solid fuel appliances as follows:
(i) Factory made flue lining systems in compliance with BS EN 1856-1:2003 or BS EN 1856-2:2004
(ii) Cast in-situ flue lining system in compliance with BS EN 1857:2003+A1:2008
Notice plates for hearths & flues
Notice plates for hearths & flues should be permanently displayed next to the flue (or electricity consumer unit or water stop tap) detailing the property address; location of installation (room); type of installation the flue is suitable for; size & construction of flue, if suitable for condensing appliance, installation date, and any other information (optional).