Annexes for a relative and why Class E does not permit them

Class E of Part 1 of the GPDO 2015 permits outbuildings required for a purpose incidental to the enjoyment of the dwellinghouse, and accommodation for a relative to live in is not an incidental purpose. The government's own technical guidance for householders says so directly: incidental use does not extend to normal residential uses such as separate sleeping accommodation. So a garden annexe for an elderly parent needs planning permission, however modest it is and however clearly it will only ever be used by family.

That is the short answer. The longer answer is about how to get the permission, and what condition you want attached to it.

The incidental test and why sleeping accommodation fails it

The word in the Order is incidental, and it carries a narrow meaning built up over decades of appeal and court decisions. A home office, a gym, a workshop, a store, a swimming pool enclosure, a garden room for hobbies: all incidental to living in the house.

Sleeping, cooking and washing are not incidental to residential use. They are residential use. A building providing them is providing accommodation, and Class E does not authorise it, whatever the size of the building or the relationship of the occupier.

This catches people out because the building often looks exactly like a permitted garden room. Two identical structures, one used as a studio and one with a bed and a shower room, sit on opposite sides of the line. Enforcement officers know this and the question they ask on a site visit is what the rooms are used for.

Claiming the building is a home office while fitting it out as a flat is the worst of the available options. It creates an unauthorised development that cannot be sold, cannot be insured properly and is plainly visible in the fixtures.

Ancillary use of the main house as the alternative argument

There is a separate and legitimate argument that does not depend on Class E. Where accommodation within the curtilage is used as part of the same single household as the main house, sharing facilities and without functional independence, the whole remains one dwelling in planning terms and no new planning unit has been created.

That argument works for a bedroom over a garage, a converted outbuilding used by a family member who eats in the main house, or a granny flat within the house itself. It works much less well for a self-contained unit with its own kitchen, bathroom, entrance and utility supplies.

The distinction is functional independence rather than the label on the drawing. A building with a kitchen, a shower room, a lockable front door and its own utility supply is a dwelling, and describing it as ancillary does not change what it is.

Note also that providing the building in the first place still needs authority. Even where the eventual use would be ancillary, the erection of a new building for residential accommodation is not covered by Class E, so permission is needed for the building.

Conditions tying an annexe to the main house

Councils grant annexe permissions routinely, and they almost always attach a tie. Typical wording restricts occupation to a person related to or dependent upon the occupiers of the main dwelling, requires the annexe to remain ancillary to the main house, and prevents its sale or letting as a separate dwelling.

Those conditions are a feature rather than a bug. They are what allows an officer to grant permission for a unit that would fail policy as a new dwelling on its own, because in a village with a settlement boundary or in the Green Belt a free-standing new dwelling would be refused.

Read the wording carefully before you accept it. Conditions that tie occupation to a named individual, rather than to a class of person, become unworkable when that person dies or moves. Conditions requiring internal connection to the main house limit the design. Where the wording is unworkable, an application under section 73 of the Town and Country Planning Act 1990 is the route to vary it, and removing a permitted development condition by section 73 covers how those applications are put.

Where the curtilage has changed shape over the years, establish its extent before designing, because Class E and the ancillary argument both depend on it. Measuring curtilage when a garden has been enlarged deals with the evidence.

Separate access, services and council tax as evidence

Councils assess whether a separate dwelling has been created on a familiar list of indicators:

No single item decides it. A separate council tax banding carries weight because it is a formal determination by a different body, and a fenced off garden with its own gate carries weight because it shows the occupier living independently.

The practical advice is to design out the strongest indicators where the intention is an annexe. Share the access, keep the garden open, take services from the main house, and avoid a separate postal address. Those choices cost nothing at design stage and are hard to reverse later.

Where a separate dwelling has been created

If the annexe is a separate dwelling, the analysis changes entirely. The use of a building previously used as a single dwellinghouse as two or more separate dwellings is a material change of use under section 55(3)(a) of the 1990 Act, and a new dwelling has to satisfy housing policy: settlement boundaries, Green Belt, access, parking, amenity space, space standards.

In many locations that application fails. In others it succeeds and is worth more than an annexe, because an unrestricted dwelling can be sold separately.

Decide which you are asking for before you apply. An application described as an annexe, granted with a tie, cannot later be treated as an independent house without a further application, and a fall-back argument about what could have been built instead sometimes helps that later case, as set out in using a permitted development fall-back in an application.

The levy position on an annexe

Where the council charges the Community Infrastructure Levy, a new annexe creates chargeable floorspace. The Community Infrastructure Levy Regulations 2010 provide an exemption for residential annexes, available where the annexe is within the curtilage of the main dwelling, is a single extension or building, and the applicant owns the main dwelling and occupies it as their sole or main residence.

Three points decide whether the exemption is actually obtained. It must be claimed and acknowledged before development starts, and a claim after the first spade in the ground is refused. Disqualifying events apply for a period after completion, including letting the annexe separately or selling it apart from the main house, and the levy becomes payable if one occurs. And the regulations are amended from time to time, so check the current text and the council's own charging schedule before relying on any of it.

Do not assume the exemption is automatic. The requirement to notify the council before starting work catches self-builders more often than any other part of the levy system.

Applying for permission, and reverting later

A householder application for an annexe is a modest submission: the form, plans and elevations, a location plan, the fee, and a short supporting statement.

Make the statement do real work. Explain who the annexe is for and why, describe how it will function as part of the household, confirm what is shared, state the relationship to the main house in design terms, and offer the tie condition yourself with wording you can live with. Offering the condition is the single most effective thing you can do, because it removes the officer's main concern before they raise it.

Reverting later is possible but not automatic. Where an annexe has been used as a separate dwelling, returning it to ancillary use is itself a change of use, and where it was built under a tie condition the condition remains until varied. Keep the permission and the approved plans with the deeds. Purchasers' solicitors ask for them, and a missing decision notice on a 15 year old annexe is a genuine problem at sale.

You can draft the Planning Statement and the Design and Access Statement for an annexe application in PlanScope in minutes, then send them for review before submission. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. A Lawful Development Certificate is the only formal way to confirm that works already carried out are lawful.