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This at-a-glance guide to stove installation is intended to provide you with some general information regarding basic stove installation requirements – it is not intended to be comprehensive. There is nothing to stop a good DIYer installing their own stove, but the installation must be 'signed off' as conforming to current building regulations and a compliance certificate issued (after the Building Control fee has been paid). You will need this should you ever decide to sell your home or if you have a stove-related insurance claim. Alternatively, in England and Wales we strongly recommend using a registered competent person from either Hetas or OFTEC who will be able to self-certify their work and issue the relevant building regulations compliance certificate. In Northern Ireland and Scotland the installation of stoves must be notified to the local Building Control department, again, so that the installation can be 'signed off' as complying with current building regulations.
Minimum flue height
4.5 metres (15') from the top of the stove
This is not only part of current building regulations but is usually also a stipulation by the stove manufacturer to ensure that there is enough updraught in the flue system for their stoves to work properly. At least one stove manufacturer that we know of specifies a greater minimum height. Flues that are less than 4.5 metres will require a flue draught calculation carried out by a flue specialist and a specification for the appropriate flue system. The installation itself will also need to pass the BS8303 (2019) spillage safety tests to ensure effective operation.
Maximum height of single skin connecting flue pipe
Recommended maximum 1400mm from the top of the stove
Preferably less, as this will help limit any flue gas heat loss so that it can safely exit the flue system and reduce the chances of condensation. If you are not using an existing chimney and flue liner, then beyond 1400mm you must use twin wall insulated flue pipe because of the excessive heat released from the single skin pipe which will naturally rise towards any combustible ceiling components. You cannot revert to single skin flue pipe once twin wall has been used at any point in the flue system. Single skin (uninsulated) flue pipe, and for that matter chimney liner, must never be used to pass through the ceiling, roof or walls. Ceilings require the use of a ventilated fire stop and walls need a purpose-made wall sleeve to prevent water ingress.
Minimum straight flue height before bending
600mm (2') from the top of the stove
In exceptional circumstances shallow bends of 15º from the top of the stove may be specified by a Hetas or OFTEC competent person to help clear some fireplace lintels. To ensue safe operation the appropriate BS8303 (2019) spillage tests should also be carried out during commissioning.
Maximum number of bends in any one flue system
Total of 4 x 45º bends in any flue system
Despite what you may see in some European stove photographs single 90º bends should never be used as they slow down the flue gas which may then allow dangerous soot deposits to build up in the bend. The only exception to this is factory-made 90º T pieces and 90º 'swept bends' (preferably with a cleaning hatch) for flues exiting from the rear of an appliance.
Maximum length of horizontal run in a flue system
150mm (6") and only permitted from the rear flue outlet of the stove
However, avoid if possible. Some flue and stove manufacturers will allow horizontal runs of up to 600mm provided that the appropriate flue draught calculations are made – but The Stove Yard do not recommend this because of the increased potential for poor updraught and soot blockages at some point in the future. If you must do this then you will need to get the different written approvals of the flue and stove manufacturers in order to satisfy Building Control and or any Hetas / OTEC inspection.
Minimum gap between single skin flue pipe and other materials
To combustible materials (eg stud and plasterboard wall): 3 x flue pipe diameter
125mm (5") flue pipe is 375mm (15") to combustible material
150mm (6") flue pipe is 450mm (18") to combustible material
To non-combustible wall or heat shield: 1.5 x flue pipe diameter
125mm (5") flue pipe is 188mm (7.5") to non-combustible material
150mm (6") flue pipe is 225mm (9") to non-combustible material
NB Non-combustible heat shields must have a 12mm air gap between them and the combustible material. See current guidance in BS8303 (2019). If in doubt always use twin wall insulated flue pipe and refer to the individual twin wall manufacturer's safe minimum distances which can differ between brands.
Please also check out the user friendly table below for a guide to air vent sizes based on Document J calculations.
Air supply for pre-2008 homes
Stoves of 5.0kW output and over require a permanently fixed open air vent or a direct external air supply (DEAS)
However, stoves of less than 5.0kW do not usually require this. Having said that, where properties have been substantially upgraded with for example, double-glazing or mechanical extraction, we would generally recommend a dedicated air vent or direct external air supply to the stove no matter what it's heat output is. Again, if a stove – no matter what its heat output, is to be installed in a room with mechanical extraction (eg Kitchen / diner) then the stove must incorporate a direct external air supply and the appropriate BS8303 (2019) spillage safety tests carried out.
Air supply for post-2008 homes
All stoves require an air vent or direct external air supply.
A permanently fixed open air vent or alternatively a direct external air supply is required for all stoves irrespective of the heat output in post-2008 and low energy homes – please refer to Document J. You should also check out our user friendly table below.
Air supply in rooms with extractor fans
Regulations for stove installations where mechanical extraction of air is present were changed in 2019 with the introduction of the revised BS8303 standard. This recommends that in such situations a stove with direct external air supply (DEAS) should be specified and that the appropriate worst case scenario spillage tests should be undertaken to ensure that there is no potential for the escape of dangerous carbon monoxide (CO) during operation. Spillage tests should only be carried out by a registered Hetas or OFTEC Installer.
Air supply for homes with Mechanical Ventilation Heat recovery (MVHR)
Only stoves with direct air supply with a DIBt tested room seal (or equivalent) should be specified
Where a mechanical ventilation heat recovery (MVHR) system is present then the revised BS8303 standard now permits the installation of a stove with a DIBt tested room-seal, such as those from Hwam. Alternatively, where the manufacturer specifically states that their appliance is suitable for use with MVHR (eg Fondis) then this can also be installed. In addition, the direct air supply vent and non-combustible ducting kit should either be supplied by the stove manufacturer or the manufacturer's specifications strictly followed in order to ensure safe and efficient operation of the stove. The appropriate BS8303 spillage tests must also be successfully completed by a recognised competent person (eg Hetas or OFTEC registered) before the installation can be 'signed off' as safe to operate.
Air supply for stoves / flues with a draught stabiliser
A permanently fixed open air vent (to Document J calculation) or direct external air supply is required for all stoves
Position of air vents
Place as near as possible to the stove to minimise cold air movements
Alternatively choose a stove with direct external air supply (DEAS) for a practical and safer alternative and which will also help eliminate nuisance draughts.
Minimum space to non-combustible materials at the side of the stove
150mm (6") minimum space from the sides of the stove to the non-combustible fireplace inner side walls
This can be reduced slightly (subject to the manufacturer's instructions) but must always be compensated by a much greater space at the top of the stove. Failure to leave enough space at the sides of the stove (or the back) would mean that the stove is likely to overheat because essentially the heat has nowhere else to go. Heat would build up within the body of the stove thus shortening the life of firebricks and fire grate etc and possibly permanently damaging the stove's bodywork, fireplace lining and even the brickwork.
Minimum space to non-combustible materials at the back of the stove
Generally there is no minimum space to non-combustible materials specified
However, always follow manufacturer's instructions. At The stove Yard we would always recommend a minimum of 75mm (3") if possible to avoid potential damaging heat build-up for the reasons outlined in the section above. Stoves with rear heat shields can help reduce this minimum distance. Don't forget to allow space for any direct external air supply inlet and non-combustible ducting. Boiler stoves will require a bigger gap to allow for pipework and bends.
Minimum space to non-combustible materials at the top of the stove
Ideally 300mm (12") from top of stove and 1200mm (4') from top of hearth
Remember, the stove installer also needs space to make good the connections to the flue pipe and to the chimney liner.
Minimum distances to combustible materials eg stud walls, soft furnishings, wooden mantels etc
These vary according to the manufacturer and type and heat output of stove
For example radiant, convecting or boiler stoves and their individual heat outputs have widely varying requirements so always check the manufacturer's instructions. Some distances can be as great as 800mm and should not be ignored. Please note that plasterboard is regarded as a combustible material and should never be used to line a fireplace opening or to create a mock chimney breast. If in doubt please refer to the heat shielding requirements set out in BS8303 (2019).
Load-bearing capacity
The weight of stove and fuel load plus the potential weight of any flue components which may bear down on the stove
Remember, chimney liner and twin wall chimney systems must always be securely and fully supported so that in practice no additional weight should ever bear down on the stove. The hearth should also be to take the weight of the person who may have to stand on it during installation or maintenance.
Minimum thickness of non-combustible hearth
125mm (5") constructional hearth
Required for all stoves (depth can include a non-comustble decorative surface) unless the manufacturer stipulates otherwise
12mm (1/2") decorative hearth
Where the stove has a tested hearth temperature of <100ºC and the manufacturer has declared it is suitable
To the best of our knowledge the 12mm decorative hearth declaration covers most stoves where the fire chamber is set well above the hearth, such as convector stoves and radiant stoves with log stores. – but always double-check the manufacturer's instructions. Radiant stoves with very low legs or low plinths don't usually deliver a temperature significantly below 100ºC to satisfy the safety requirements for placement on a 12mm decorative hearth. Single piece purpose made non-combustible hearths of the appropriate size can be safely placed on most stable surfaces including wood and laminate flooring. The upcoming replacement for the current CE BS EN13240 test (BS EN14610) will also test temperatures at 500mm and 1,000mm in front of the hearth. Depending on the configuration of the stove these can sometimes be significantly higher than the hearth temperature. Some manufacturers already declare these figures.
Minimum distance of non-combustible hearth from front of stove
225mm (9") from front of stove (includes edge of stove's ash lip)
Where possible we recommend a hearth that goes beyond the furthest out-swing of the stove door plus a minimum of 50mm (2") to catch any potentially live ash – this is particularly important for wide body, single door stoves where the door can project well beyond the minimum 225mm non-combustible hearth.
Minimum distance of non-combustible hearth from sides of stove
150mm (6") at each side
Where possible, for radiant stoves we recommend adding a further 25mm (1") at each side for each additional kW of heat output to avoid excessive heat build-up from high output stoves.
