Flues and chimneys under Class G and the one metre rule
A wood burner flue is permitted development under Class G if it stays under one metre above the highest part of the roof. How the measurement works, and the narrower restriction that applies on designated land.
Class G permitted development covers the flue for your wood burner, and the limit that matters is height: the flue must not exceed the highest part of the roof by one metre or more. Under a metre above the ridge and you are inside the allowance. At a metre or above you are not, and you need planning permission. That single figure decides most domestic flue installations.
The second limit catches people in conservation areas, and it is narrower than the usual designated-land rule.
What Class G permits
Class G of Part 1 of Schedule 2 to the Town and Country Planning (General Permitted Development) (England) Order 2015 permits the installation, alteration or replacement of a chimney, flue or soil and vent pipe on a dwellinghouse.
Three things follow from the wording. It covers replacement as well as new installation, so swapping a failed flue for a new one of the same height is permitted development. It covers soil and vent pipes, which is why a new bathroom's vent pipe does not normally need permission. And it applies to a dwellinghouse, which means flats and maisonettes are outside Part 1 altogether and a flue on a converted building containing flats needs an application.
Class G says nothing about the appliance inside. A stove, boiler or flueless heater is not development. The flue through the wall or roof is.
The one metre limit, and what it is measured from
Development is not permitted if the height of the chimney, flue or soil and vent pipe would exceed the highest part of the roof by one metre or more. Read that carefully. A flue finishing exactly one metre above the ridge fails. The permitted range stops just below it.
The measurement is taken against the highest part of the roof of the dwellinghouse, not the roof immediately below the flue. So a flue rising through the roof of a single storey rear extension is measured against the main ridge of the house. That reading gives much more headroom than people assume, and it is the reason a rear extension stove flue is usually permitted development even when the pipe looks tall against the extension itself.
Where the house has a flat roof, the highest part of the roof is the top of the parapet or the roof surface, whichever is higher, and the same one metre rule applies from there.
If the margin is within a few centimetres, get the flue height dimensioned on a section before the installer orders the components. A flue that turns out to be 1.05 metres above the ridge is unauthorised development, and a buyer's solicitor will find it.
Designated land and the elevation facing a highway
On article 2(3) land, which means conservation areas, National Parks, National Landscapes, the Broads and World Heritage Sites, Class G is restricted but not removed.
The restriction applies where the flue would be installed on a wall or roof slope that both fronts a highway and forms either the principal elevation or a side elevation of the house. Both conditions have to be met.
So in a conservation area:
- A flue on the rear roof slope is still permitted development, because the rear is neither the principal nor a side elevation fronting a highway.
- A flue on the front roof slope of a house facing the road is not.
- A flue on the side elevation of a corner plot, where that side faces a road, is not.
- A flue on the side elevation of a mid-terrace with no highway on that side is permitted.
Highway includes public footpaths and bridleways, so a house fronting a public path has a highway-fronting elevation even without a road. Permitted development rights can also be removed by an Article 4 direction or by a condition on the original permission, so check both before relying on the class. Our note on front garden paving and Class F covers the same designated-land logic for a different class.
Wood burners, smoke control areas and fuel rules
Permitted development tells you whether you can put the flue up. It does not tell you what you may burn.
Most urban areas of England are smoke control areas under the Clean Air Act 1993. Inside one, you may only burn authorised fuels, or use an appliance that has been exempted by the Secretary of State for the fuel you intend to use. Burning ordinary wood in a non-exempt stove in a smoke control area can bring a financial penalty from the local authority.
Separate regulations have also restricted the sale of the most polluting domestic fuels in England, phasing out bagged house coal and wet wood sold in small volumes. Check the current rules on gov.uk before buying fuel in bulk.
Where a scheme is larger than a single stove, for example a biomass boiler serving several dwellings or a commercial appliance in a residential area, air quality becomes a planning matter in its own right and an Air Quality Assessment may be needed, particularly inside an Air Quality Management Area.
Building Regulations are a separate test
Planning permission and Building Regulations approval are different systems with different limits, and satisfying one says nothing about the other.
Approved Document J governs combustion appliances and flues. It sets where the terminal must sit in relation to the roof surface, the ridge and nearby openings, the hearth and clearances around the appliance, the flue liner and its size, and the requirement for a carbon monoxide alarm when a solid fuel appliance is installed.
The practical route for most households is a registered installer working under a competent person scheme, which allows the work to be self-certified rather than inspected by building control. Solid fuel installers register with the relevant scheme, gas work must be done by a Gas Safe registered engineer, and oil appliances have their own scheme. Keep the certificate. It is the document a conveyancer asks for.
Where the flue needs to clear the ridge for draught reasons but Class G caps the height, the Building Regulations requirement does not override the planning limit. You apply for permission.
Listed buildings need consent whatever Class G says
Permitted development rights have no effect on listed building control. Installing a flue on a listed building affects its character, so it needs listed building consent, and that application is free.
Expect the conservation officer to care about three things: whether an existing historic flue can be reused, where the new terminal appears in views, and how the penetration through historic fabric is detailed. Reusing a blocked original chimney with a liner is almost always the preferred answer, and it often costs less than a new twin-wall system on the outside of the building.
A short Heritage Statement explaining the significance of the building, the options considered and why the chosen position causes least harm is what makes these applications decidable.
When you need an application instead
If the flue fails Class G, the route is a householder planning application. What makes the difference to the outcome:
- Elevations at a proper scale showing the flue, its diameter and its height, with the ridge height dimensioned on the same drawing.
- A position chosen to be least visible from the street, usually on a rear slope or behind a chimney stack.
- A finish specified rather than left open. Black or dark grey powder coated is usually acceptable where stainless steel is not.
- A short design and heritage justification where the house is in a conservation area or adjoins a listed building.
- Evidence that the alternative of reusing an existing flue was considered.
A short Planning Statement carrying those five points keeps the application brief and decidable, and householder applications are determined in eight weeks when the submission is complete.
Measure the ridge, measure the proposed flue top, and write the difference on the drawing before anything is ordered. You can browse the report types by category if the house is listed or in a conservation area and the application needs heritage support.
This is general guidance, not legal advice, and a lawful development certificate is the only formal way to confirm that works are lawful. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
How high can a flue be under permitted development?
Class G is not permitted if the flue would exceed the highest part of the roof by one metre or more. A flue finishing exactly one metre above the ridge fails, so the usable range stops just below that. Get the height dimensioned on a section before the components are ordered.
Is the one metre measured from the ridge or from where the flue comes through?
From the highest part of the roof of the dwellinghouse. A flue rising through a single storey rear extension is therefore measured against the main ridge of the house, which gives considerably more headroom than measuring against the extension roof would.
Can I fit a wood burner flue in a conservation area?
Often yes. The restriction applies only where the flue would be installed on a wall or roof slope that both fronts a highway and forms the principal or a side elevation. A flue on the rear roof slope of a conservation area house normally remains permitted development.
Do I need planning permission for the stove itself?
No. Installing an appliance inside the house is not development. What Class G regulates is the flue or chimney passing through the wall or roof. Building Regulations do apply to the appliance, the hearth, the flue and the carbon monoxide alarm under Approved Document J.
Does Class G apply to a flat?
No. Part 1 rights belong to dwellinghouses, so a flat or maisonette, including one in a converted house, is outside Class G altogether. A flue serving a flat needs planning permission however modest it is, and the freeholder's consent will be needed separately.
What about a flue on a listed building?
Permitted development rights have no effect on listed building control, so listed building consent is needed and the application is free. Reusing a blocked original chimney with a liner is usually the preferred solution and is often less expensive than an external twin-wall system.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.