Householder Extensions and Conversions – Page 6

Flues and soil vent pipes on a front roof slope

Class G of Part 1 of the GPDO 2015 permits a chimney, flue or soil vent pipe on a house below one metre above the ridge, except on a highway-facing front or side elevation on designated land.

Extending a house on a corner plot with two frontages

Two highway frontages mean two restrictions in Class A. Why a side extension is usually unavailable on a corner plot, and which design moves get permission.

Party wall notices running alongside a planning application

The council has no role in party wall matters, but the two month notice period can decide your start date. How to sequence notices against a planning application.

Eaves height limits when an extension sits near a boundary

Class A of the GPDO caps extension eaves at 3 metres within 2 metres of a boundary. How the measurement works on a sloping site, and what to show on the drawings.

Solar panels on a pitched roof and the projection limit

Roof-mounted solar on a house must not protrude more than 200 mm beyond the roof plane or rise above the highest part of the roof. Tilt frames and shallow pitches are where installations break those limits.

Render and cladding on a house and the materials condition

Class A permits alterations to a house provided the materials are of a similar appearance to the existing exterior. On designated land the cladding right disappears, and external wall insulation raises thickness problems the Order never anticipated.

Replacing windows where an Article 4 direction applies

Where an Article 4 direction has withdrawn householder permitted development rights, replacing windows normally needs planning permission. The exception is a genuine like for like replacement that does not materially affect external appearance.

Why the principal elevation is excluded from Class A

Front extensions always need permission because Class A excludes anything beyond the principal elevation. This covers identifying that wall, corner plots with two frontages and making the design case.

Rear extension depth from the original rear wall

Class A depth limits are measured from the original rear wall, not the current one, so an earlier kitchen extension eats the allowance. This covers the datum, the limits and the evidence councils accept.

Setting a rear dormer back from the eaves

A permitted development dormer must sit 200 millimetres back from the original eaves along the slope. Nothing requires a party wall set in, and design guides ask for one anyway.

How to measure the 45 degree line from a neighbour window

Draw the 45 degree line from the centre of the neighbour's nearest habitable room window, in plan and in section. This explains the method, the windows that count and the cases where a breach still gets permission.

27 September 2026Read article →

Extending a flat or maisonette and why it differs

Part 1 of the GPDO does not reach flats, so every extension needs permission. The ownership certificate trap, the licence to alter, and the amenity questions officers ask about the flats above and below.

Subdividing a house into two flats: layout standards

Splitting a house into two flats is always a material change of use. Here is what councils measure: floor areas, ceiling height, daylight, sound, storage, access and overnight parking stress.

Replacement windows in an unlisted period house

Window replacement in an unlisted house is permitted development unless an Article 4 direction has removed the right. Here is how to check, and what profile detail a conservation officer will expect.

Annexe or separate dwelling: where the line falls

The difference between an annexe and a second dwelling turns on the planning unit and the degree of separation, not on floor area. Here is how councils apply the test and how to confirm your position.

Glazed link extensions to a period house

A glazed link keeps the original building reading as a complete object, which is why officers accept it where an abutting extension would be refused. It also takes a linked outbuilding out of the Class E allowances.

Flat or pitched roof on a single storey extension

The eaves height limit within 2m of a boundary, not taste, decides most extension roof forms. Here is the arithmetic, the minimum pitch each covering needs, and how each form reads against the host house.

Hip to gable conversions and the effect on a pair

Hip to gable is permitted development under Class B on most houses, with a 40 or 50 cubic metre allowance that includes earlier roof work. On a matched semi-detached pair the design argument is the harder one.

Rooflights on a front roof slope in a conservation area

Class C of the GPDO 2015 has no blanket conservation area exclusion, so a flush front rooflight is often lawful where a dormer is not. The 150mm projection limit and Article 4 directions decide it.

Extending a semi where the neighbour has already extended

A grant next door is evidence, not entitlement. How consistency is treated, how amenity baselines shift, and how to frame the argument.

Extending a bungalow without losing the roofline

On a uniform bungalow estate the roof is the building. What councils look at when a ridge goes up, and the options that avoid the argument.

Wrap around extensions and light to the rooms you keep

A side return and rear extension built together take daylight from the rooms in the middle of the plan. Here is how to design around that, and what the council checks.

Extending a house covered by an Article 4 direction

If an Article 4 direction covers your address, the extension your neighbour built without applying needs planning permission from you. What the direction removes, why no fee is payable, and how to check.

Subordinate extension design: ridge, eaves and the host house

Ridge set down, eaves line and width against the original elevation decide most householder applications. What subordination means in adopted design guidance and how to show it on a drawing.