Do you need planning permission for a wood burner flue?

The rule, and the common misreading

(b) the height of the chimney, flue or soil and vent pipe would exceed the highest part of the roof by 1 metre or more; (c) in the case of a dwellinghouse on article 2(3) land, the chimney, flue or soil and vent pipe would be installed on a wall or roof slope which: (i) fronts a highway, and (ii) forms either the principal elevation or a side elevation of the dwellinghouse;

The words are "1 metre or more", so a flue that finishes exactly 1 metre above the ridge is outside Class G. A summary that says "up to 1 metre" gets this wrong. Design the flue to finish below 1 metre.

The technical guidance defines the highest part of the roof as the ridge line of the main roof, or the highest roof where the roofs are flat, and says chimneys, firewalls and parapets above the ridge are ignored. An existing chimney stack does not raise the datum.

The height a stove maker or installer needs for the flue to draw properly, and the height the Order allows, are different questions. If the flue has to finish 1 metre or more above the ridge, you need planning permission.

On protected land

The article 2(3) test has two parts, and both must be met before the flue is excluded. A flue on the rear wall or rear roof slope is not caught by paragraph G.1(c), even where the back of the house faces a lane, provided the rear is not the principal elevation. A flue on a side wall facing a side street, or on the front slope, is caught. The guidance says an elevation at more than 45 degrees to the highway will not normally be treated as fronting it.

Listed buildings and flats

• Listed buildings. Class G has no listed building exclusion, but section 7 of the Planning (Listed Buildings and Conservation Areas) Act 1990 requires consent for works that would affect the building's character. A new flue on a listed house is likely to need listed building consent.
• Flats. Part 1 does not apply to flats. Part 14, Class E is a separate right for a flue forming part of a microgeneration biomass heating system on a house or a block of flats, with the same 1 metre test and a bar on walls or roof slopes fronting a highway in a conservation area or World Heritage Site. For heat, microgeneration is capped at 45 kilowatts thermal (Energy Act 2004, section 82(6) and (8)).

Building Regulations and smoke control

Installing a stove and flue is building work. The Building Regulations treat anything Part J (combustion appliances) applies to as a controlled service or fitting (regulations 2 and 3), so the installation must meet the Regulations: see Building Regulations approval for the routes.

If your council has declared a smoke control area under section 18 of the Clean Air Act 1993, it can impose a financial penalty of £175 to £300 on the occupier for smoke emitted from a chimney (Schedule 1A, paragraph 3), unless the smoke control order exempts that building or fireplace. The Order says nothing about what you burn, so ask the council's environmental health team.

What this means for you

• Measure from the main ridge, not from a chimney stack.
• On protected land, put the flue on a rear slope or a wall that does not front a road.
• Use the permitted development checker to confirm the position before ordering the flue kit.

Getting certainty

A lawful development certificate under section 192 of the Town and Country Planning Act 1990 confirms that a proposed flue would be lawful. The council has 8 weeks to decide. It is worth having on a corner plot, where which elevation is principal can be arguable. See lawful development certificates.