Why Part 1 rights do not apply to a flat or maisonette

Part 1 of Schedule 2 to the GPDO 2015 is headed development within the curtilage of a dwellinghouse, and the Order's own definition does the damage. Article 2 states that dwellinghouse does not include a building containing one or more flats, or a flat contained within such a building. So every class in Part 1, from the rear extension in Class A to the satellite dish in Class H, is unavailable to a flat or a maisonette. There is no size below which it becomes permitted, and no Article 4 direction to blame.

That single definition explains most of the confusion landlords and leaseholders arrive with. The works themselves might be modest. The route to doing them is a planning application.

The definition that excludes flats

A flat, in the Order, is a separate and self-contained set of premises constructed or adapted for use as a dwelling, forming part of a building from which it is divided horizontally. The horizontal division is the test that decides borderline cases.

Two self-contained units in a building divided vertically, each occupying its own full height slice, are houses. Two units stacked one above the other are flats, whatever the sales particulars call them. A ground floor unit with a first floor unit above it in the same building is two flats even where each has its own front door to the street, and even where the upper unit occupies two storeys.

This is why a conversion that was marketed as two cottages can turn out to have no permitted development rights at all. Check the division before advising on the works, and check it against the physical arrangement rather than the title plan.

What a maisonette owner can and cannot do

Nothing in Part 1 is available, which rules out a rear extension, a roof extension or dormer, a porch, an outbuilding in the garden, a new area of hard standing within the curtilage, a flue, and an antenna on the elevation.

Several other parts of the Order do still apply, and they are worth knowing because they cover a surprising amount of ordinary work.

Part 2 Class A permits a gate, fence, wall or other means of enclosure within the usual height limits, and it is not confined to dwellinghouses. Part 2 Class C permits the painting of the exterior of any building, which covers repainting a flat's elevation subject to the advertisement exclusion. Those rights are set out in more detail in painting and external alterations under Part 2.

Part 14 is drafted differently again. Its classes for solar equipment and air source heat pumps expressly refer to a dwellinghouse or a block of flats, so the rights exist for the building rather than being withdrawn by the Part 1 definition. The conditions and limits still apply, and for a block the installation is usually a matter for the freeholder.

Part 20 contains the upward extension classes, including provision for new dwellings on top of existing blocks of flats. That is a route for a building owner, with prior approval and a long list of conditions, rather than for an individual leaseholder.

Communal areas and the freeholder's position

Ownership shapes what is possible before planning does. In a typical long lease the demise stops at the internal surfaces, and the structure, the roof, the external walls and the grounds remain with the freeholder.

A leaseholder who wants to extend into a garden or alter a roof is proposing work to land and structure they do not own. Planning permission can still be sought, because an applicant does not need to own the land, but the application triggers the ownership certificates in the procedure order. A leaseholder with at least seven years unexpired is an owner for those purposes, and notice must be served on the freeholder and any other qualifying owner, with the certificate completed accordingly.

Serving that notice usually starts the commercial conversation rather than ending it. Expect the freeholder to want a premium, a deed of variation or a licence, and allow for it in the programme.

Alterations inside a flat and when permission is needed

Works affecting only the interior of a building, or not materially affecting its external appearance, are not development at all under section 55 of the Town and Country Planning Act 1990. That is the provision most internal work to a flat relies on, and it holds for moving a non-structural partition, refitting a kitchen or replacing a bathroom.

Three things take internal work outside it.

Creating additional underground space is expressly treated as development even where it is internal, which catches basement excavation beneath a ground floor flat.

Subdividing one flat into two is a material change of use, because use as two or more separate dwellings is development in its own right. The number of units matters, not the floor area.

Listed building consent is a separate regime with no internal exemption at all. In a listed building, removing a cornice, altering a plan form or replacing a staircase needs consent whether or not anything is visible outside.

Window replacement sits awkwardly in the middle. A like for like replacement in a flat will often not materially affect the external appearance, and a change from timber sashes to white plastic casements in a conservation area clearly will.

Change of use within a building containing flats

The change of use classes in Part 3 are drafted around uses rather than around dwellinghouses, so some of them do apply to premises within a building that also contains flats. A commercial unit on the ground floor of a converted terrace may have a prior approval route available to it that the flat above does not.

Two cautions. Converting a single dwelling into two or more dwellings is not permitted development under any class, so a flat to two flats scheme is always a full application. And a change from a single dwelling to a small shared house in Class C4 is permitted under Part 3 Class L only between the use classes specified, and many authorities have removed it by Article 4 direction. How those directions are made, and how to check whether one covers an address, is set out in how a council makes an Article 4 direction.

Applying for permission instead

The application type matters more than people expect. Householder applications are for proposals to alter or enlarge a single dwellinghouse, and they are not available for flats or maisonettes. Works to a flat go in as a full application.

Three consequences follow.

The appeal point is the one that costs people money. A refusal on a flat extension carries the full six month window and the standard written representations procedure, which is slower but allows a fuller case to be made. Plan the documents accordingly, since a Planning Statement addressing the development plan policies on amenity, design and the character of the building does more work on a flat application than on a householder one, where the officer is often working from drawings alone.

Measurement conventions still matter even without permitted development rights, because the policy tests on height and projection often mirror them. The approach to measuring height from adjacent ground carries across.

Lease consent as a separate requirement

Planning permission is not authority to carry out the works. A lease with a qualified covenant against alterations requires the landlord's consent, and for improvements the Landlord and Tenant Act 1927 provides that consent must not be unreasonably withheld, which is a narrower protection than it sounds.

Work affecting a party structure brings the Party Wall etc. Act 1996 into play, with its own notice periods that run independently of the planning timetable. Building Regulations approval is separate again, and in a block of flats the fire safety implications of altering a protected route or a compartment wall are likely to be the controlling constraint rather than planning.

Sequence them: establish the lease position, then apply for planning permission, then deal with party wall and building control. Reversing the first two wastes a fee more often than it saves time.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it, and remember that a Lawful Development Certificate under section 192 of the Town and Country Planning Act 1990 is the only formal way to confirm that works would be lawful without permission.

PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.