Summary
- Part J governs combustion appliances — air supply (J1), flues and chimneys (J2/J3), hearths, protection from fire and heat (J4/J5) and carbon monoxide alarms — with wood-burning stoves the dominant domestic trigger.
- Flue outlet positions relative to the ridge, roof windows and adjoining buildings are set out in AD J Diagram 17 and are a design-stage check, not an installer's afterthought.
- Solid fuel installations need a CO alarm to BS EN 50291 in the same room, a compliant hearth, and either a HETAS (or equivalent) competent-person installation or Building Control inspection — keep the commissioning certificate.
What the Building Safety Act requires for Part J on non-HRB domestic jobs
Every stove, boiler, open fire and oil tank engages Part J. On extensions and refurbishments the recurring issues are: adequate combustion air (particularly once the house is made more airtight under Part L), flue routes and outlet positions that clear roof windows and neighbouring openings, hearth construction, and separation of oil/LPG storage from boundaries and buildings.
The interaction with ventilation is the safety-critical one. Extract fans (Part F) can depressurise a room and pull flue gases back down an open-flued appliance — AD J requires spillage testing where extract is added to a room containing an open-flued appliance. As Principal Designer (BSA) you should flag this whenever a kitchen extension with a powerful cooker hood shares air with a stove or open fire.
Installation by a HETAS/Gas Safe/OFTEC registered installer self-certifies compliance; otherwise the work must be inspected by Building Control. Either way, log the commissioning certificate and the notice plate details in your handover pack.
Key design risks and evidence needed (RIBA Stages 2–4)
- Stage 2: locate appliances and flue routes early — a stove in the corner of an open-plan extension often cannot achieve a compliant flue route once the roof design is fixed.
- Stage 3: check flue outlet positions against AD J Diagram 17 (e.g. 600 mm above the ridge for solid fuel at the ridge, 2.3 m horizontal clearance to openable rooflights); coordinate hearth dimensions with floor build-ups.
- Stage 4: specify the flue system (BS EN 1856-1 twin-wall or BS EN 15287 design), hearth construction (minimum 12 mm non-combustible for closed stoves declared ≤100°C hearth temperature, otherwise 125 mm constructional hearth), permanent air vent sizing, and the CO alarm to BS EN 50291.
Standards and references you should be citing
- BS EN 15287 — chimney design, installation and commissioning.
- BS EN 1856-1 — metal system chimneys (twin-wall flue specification).
- BS EN 50291 — carbon monoxide alarm specification (required for all solid fuel appliance installations; extended to all fixed combustion appliances in rented homes under separate regulations).
- HETAS Guide / OFTEC technical books — competent person scheme standards for solid fuel and oil respectively.
- BS 5410-1 — oil storage tank siting and fire separation distances.
Stove installation compliance checklist
| Item | Requirement | Evidence to log |
|---|---|---|
| Combustion air | Permanent vent sized to appliance rating (appliances >5 kW output in airtight homes need dedicated air) | Vent calculation and location on plan |
| Flue outlet | Position per AD J Diagram 17 relative to ridge/openings | Roof plan/section showing clearances |
| Hearth | 12 mm non-combustible (compliant stove) or 125 mm constructional | Hearth detail drawing |
| CO alarm | BS EN 50291, same room as appliance | Specification clause + commissioning record |
| Installation | HETAS/Gas Safe/OFTEC self-cert or Building Control inspection | Certificate + notice plate details |
Common pitfalls that catch out sole practitioners
- Stoves added to airtight extensions with no dedicated air supply — the appliance starves or spills when the extract fan runs.
- Flues that cannot clear a later-added rooflight; check clearances against the final roof window layout, not the planning drawings.
- Assuming the stove installer will 'sort the hearth' — hearth construction interacts with your floor build-up and is a design detail.
- DEFRA smoke control areas ignored: in most urban areas only exempt appliances burning authorised fuels are lawful, and the client should be told in writing.
Frequently asked questions
Does a wood-burning stove installation need Building Regulations approval?
Yes — it is controlled building work under Part J. A HETAS (or equivalent) registered installer can self-certify and notify; otherwise a building notice or full plans application with Building Control inspection is required. The commissioning certificate and CO alarm are the key evidence items.
How close can a flue terminate to a roof window?
For solid fuel, AD J Diagram 17 requires the flue outlet to be at least 2.3 m horizontally from an openable rooflight, or 1 m above it if closer. Positions relative to the ridge, adjacent buildings and boundaries all carry their own dimensions — check them at design stage while the roof can still move.
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