Do I need planning permission to convert a house into flats in London?
Yes. Using a building that was one home as two or more separate dwellinghouses is a material change of use under section 55(3)(a) of the Town and Country Planning Act 1990, and no permitted development right covers it. The fee is £610 for each additional dwelling, and our drawings start at £1,195.
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Why permitted development does not apply
Section 55(3)(a) of the 1990 Act says that using a single dwellinghouse as two or more separate dwellinghouses involves a material change of use (Town and Country Planning Act 1990, section 55). A material change of use is development, and development needs permission unless a rule grants it.
So a house cannot be split into flats without planning permission. However many flats you plan, the starting point is an application. Our glossary entry on permitted development covers the work that does not need one.
What the application costs
From 1 April 2026 the fee for changing a single dwellinghouse into two or more dwellinghouses, fewer than ten in total, is £610 for each additional dwellinghouse. Turning one house into two flats adds one dwelling, and three flats add two.
The council has 8 weeks, from the day after receipt, to decide an application that is not major development (DMPO 2015, article 34(2)(b)). You can agree a longer period in writing.
Drawings for turning a house into two flats start at £1,195.
What the council will test
Expect questions about room sizes, daylight, outlook, bin and cycle storage, parking and how the street will cope with extra households. The Nationally Described Space Standard asks for a floor to ceiling height of 2.3 metres across at least 75% of the gross internal area of a dwelling, which matters in low loft or basement rooms.
Our flat conversion drawings service sets out the plans, elevations and layouts such an application needs.
Building regulations and the rest of the paperwork
Separate flats need fire separation, sound insulation between dwellings, escape routes and individual services, all assessed under building regulations. Read our building control guide for how that process works.
If the house is rented to several unrelated sharers instead, the HMO rules apply. See permission for an HMO.
Our fixed fees
Drawings for turning a house into two flats start at £1,195. For three or more flats the starting fee is £1,795. The council's application fee is paid separately.
Sources
Every figure on this page, where it comes from and a link to the original.
| Figure | Source | Link |
|---|---|---|
| two or more separate dwellinghouses | Town and Country Planning Act 1990 s55(3)(a): use as two or more separate dwellinghouses of a building previously used as a single dwellinghouse involves a material change in the use (source wording: two or more separate dwellinghouses) | www.legislation.gov.uk |
| £610 | Statutory fee from 1 April 2026, SI 2012/2920 Sch 1 Pt 2 category 12(1)(a): change of use of a single dwellinghouse to two or more (fewer than 10) dwellinghouses, per additional dwellinghouse | assets.publishing.service.gov.uk |
| 8 weeks | DMPO 2015 art 34(2)(b): decision period for an application that is not major development (source wording: 8 weeks beginning with the day immediately following receipt) | www.legislation.gov.uk |
| £1,195 | DrawingsDirect starting fixed fee for house to two flats conversion drawings, from the published price list | drawingsdirect.co.uk |
| £1,795 | DrawingsDirect starting fixed fee for house to three or more flats drawings, from the published price list | drawingsdirect.co.uk |
| 2.3 | Nationally Described Space Standard: minimum floor to ceiling height for at least 75% of Gross Internal Area (source wording: 2.3 metres) | assets.publishing.service.gov.uk |