Documents for converting a house into flats

Converting a house into flats is a material change of use under section 55 of the Town and Country Planning Act 1990 and always needs planning permission, however minor the building works. There is no permitted development route for subdividing a single dwelling into two or more self-contained flats in England. The house to flats conversion documents pack is therefore a full planning application, and the parts that decide it are space standards, amenity and refuse provision, and parking evidence.

Councils see a lot of these applications and refuse a fair share. The refusals cluster on the same four points every time.

Why a conversion is a material change of use

Section 55 defines development to include the making of any material change in the use of buildings or land, and expressly treats the use as two or more separate dwellinghouses of a building previously used as a single dwellinghouse as involving a material change of use. That is the statutory hook, and it applies whether the conversion is into two flats or six.

The reverse is not symmetrical. Combining flats back into a single house is usually also a material change and needs permission, though some authorities take a more relaxed view. Check rather than assume.

Two related points catch investors. A house in multiple occupation is a different question with its own use class rules and its own Article 4 directions. And works to the building that would be permitted development for a single house lose those rights once the building contains flats, because most Part 1 rights apply to dwellinghouses rather than to flats.

Internal layout, space standards and daylight

The Nationally Described Space Standard sets minimum gross internal areas by number of bedrooms, bed spaces and storeys, along with minimum bedroom sizes and a minimum floor to ceiling height. It applies where a local planning authority has adopted it through its local plan, which most now have. Check the adopted policy and any housing supplementary guidance.

Where the standard applies, undersized units are refused, and the deficit is not curable by argument. Design to the figures from the start. Lower ground and basement units need particular care, because a unit that meets the area standard but has one small window to a lightwell will attract an objection on outlook and daylight even where it passes on floorspace.

Single aspect north-facing units are the other recurring problem. They are not prohibited, but a scheme made up entirely of them invites a refusal on the quality of accommodation, and the argument is easier to win when the Design and Access Statement shows the alternatives that were tested.

Amenity space, bin and cycle storage

Three provisions decide more conversions than anything else, and all three are visible on a single drawing.

Private or shared external amenity space, sized to the local standard, with an explanation of how a rear garden is allocated between flats. Refuse and recycling storage within a reasonable carrying distance of the collection point, sized for the number of units and the council's own bin dimensions. And secure, covered cycle parking, usually one or two spaces per flat depending on the local standard.

The common failure is a plan that shows bins in the rear garden with no side access, meaning residents would carry refuse through a flat. Officers spot it immediately. Where there is no side access, the answer is usually a front garden bin store designed as part of the elevation rather than an afterthought, with a note on how it is screened.

Take the dimensions from the council's own waste guidance rather than a generic figure. Bin sizes and collection arrangements differ between authorities, and a store drawn to the wrong size is a condition or a refusal.

Parking evidence and on-street pressure

A conversion increases the number of households without increasing the frontage, so the parking question is about on-street capacity rather than about the driveway.

Where the site is in a controlled parking zone with good public transport, many authorities will accept a car-free or car-capped scheme secured by a legal agreement removing residents' eligibility for permits. Where it is not, expect to be asked for evidence. A Parking Survey using the Lambeth methodology, surveying on-street occupancy overnight on a weekday and at the weekend, outside school holidays, gives a stress figure the highway authority recognises.

Set out the existing use's likely demand as well as the proposed. A five bedroom house in multiple occupation can generate more parking demand than three one bedroom flats, and saying so with evidence changes the conversation.

Sound insulation between units

Separating floors and walls between flats have to meet Approved Document E of the Building Regulations, and new dwellings formed by a material change of use are subject to pre-completion testing or to an approved construction detail route.

This is building control rather than planning, but it has a planning consequence. Meeting the acoustic standard in an existing timber floor usually means a build-up that adds depth, and in a Victorian house with existing ceiling heights that can push a unit below the minimum floor to ceiling height the space standard requires. Work the section through before fixing the layout.

Where the conversion sits above a commercial unit, the noise question changes character and an assessment of plant and activity noise is usually needed, as set out in the guidance on reports for flats above shops in a mixed use scheme.

Fire and building regulations running alongside

Conversions need a fire strategy that works for the building as built, covering protected escape routes, the standard of doors, detection and alarm provision, and the arrangements at the head and foot of the common stair.

The usual crunch is the stair. An escape route through a habitable room, an open plan ground floor with the stair rising from it, or an inner room arrangement will all need resolving, and the solutions can affect the layout the planning drawings show. Settle the escape principle before submission rather than after.

Where the building is 18 metres or more or has seven or more storeys, the planning stage fire statement regime applies. Most house conversions are nowhere near that, but conversions of larger buildings are.

The pack the council expects

For a straightforward two or three flat conversion of a suburban house, the submission usually runs to:

1. Application forms, correct fee, ownership certificate, location plan and block plan.
2. Existing and proposed floor plans and elevations, with gross internal areas annotated per unit.
3. A site plan showing refuse and cycle storage, amenity space allocation and any parking.
4. A Planning Statement addressing the development plan policies on conversions, amenity, parking and housing mix.
5. A design and access statement where the external works are more than minor.
6. A parking survey where the highway authority or the local list requires one.
7. A noise assessment where the site is near a commercial use or a busy road.

Check the council's local validation list before submitting. It is the document that decides whether your application is registered, and it varies more between authorities than any other part of the process. Browse the full set of report types to match the list to the documents you need.

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.