Section 257 HMO: Converted Flats Licensing in England

Section 257 of the Housing Act 2004 creates a separate category of HMO that catches landlords off guard: converted buildings containing self-contained flats where the conversion did not comply with Building Regulations. The licensing rules for these properties are different from standard HMOs, and the consequences of getting it wrong are the same — civil penalties up to £40,000.

What Makes a Building a Section 257 HMO?

A building qualifies as a Section 257 HMO if it meets all three conditions:

1. It has been converted into self-contained flats — the occupants of each flat have their own kitchen, bathroom, and entrance within the flat
2. The conversion did not comply with the Building Regulations in force at the time — specifically the 1991 Building Regulations or whatever version applied when the work was done
3. Less than two-thirds of the flats are owner-occupied — meaning the building is predominantly rented

The critical distinction from a standard HMO is that the individual flats are self-contained. The occupants are not sharing kitchens or bathrooms between flats. What triggers Section 257 is the building-level conversion quality — poor fire separation between flats, inadequate soundproofing, substandard structural work.

The Building Regulations Test

The test turns on whether the conversion work met the Building Regulations when it was carried out. In practice, this catches:

• Victorian and Edwardian houses converted into bedsits or flats before building control was required — many of these have no Building Regulations completion certificate because none was applied for
• Houses converted in the 1970s and 1980s with minimal or non-compliant work — partition walls that do not meet fire resistance standards, no fire doors between flats, inadequate escape routes
• More recent conversions done without Building Control sign-off — the work may have been done competently, but without a completion certificate the council has no evidence of compliance

The absence of a Building Regulations completion certificate does not by itself prove that the conversion failed the applicable standards. Ask the council what evidence it accepts to establish whether the conversion complies.

Section 257 HMOs Are Exempt from Mandatory Licensing

Here is the part that confuses landlords: Section 257 HMOs are recognised as HMOs under the Act, but they are specifically excluded from mandatory licensing under the Licensing of Houses in Multiple Occupation (Prescribed Description) (England) Order 2018.

This means a converted building with five flats, all rented, that fails the Building Regulations test is not caught by the national mandatory HMO scheme — even though it has more than five occupants across multiple households.

Instead, Section 257 HMOs are regulated through local authority discretionary schemes:

• Additional licensing — many councils include Section 257 HMOs in their additional licensing designations. Birmingham's citywide additional scheme, for example, explicitly covers Section 257 properties.
• Dedicated Section 257 designations — some councils create specific licensing designations for converted buildings.

If your local council has no active additional licensing scheme and no Section 257 designation, the building does not need a property licence — though it remains subject to the Housing Health and Safety Rating System (HHSRS), management regulations, and general safety standards.

How to Check Whether Your Building Needs a Licence

1. Confirm the building is a Section 257 HMO — check whether the conversion meets the applicable Building Regulations standards. If it does not, and fewer than two-thirds of flats are owner-occupied, it qualifies.
2. Check your council's licensing designations — look up whether your local authority has an active additional licensing scheme that covers Section 257 HMOs. The council's licensing pages should list the property types covered.
3. Check the geographic scope — additional licensing schemes sometimes apply only to designated wards, not the whole council area.

If the building meets all the Section 257 criteria and falls within an active local scheme, you need a licence for the building (not per flat — the licence covers the whole building).

What the Licence Covers

A Section 257 HMO licence typically covers:

• The common parts of the building (hallways, stairs, communal entrance)
• Fire safety for the building as a whole (fire detection, escape routes, fire doors between flats)
• Structural and repair standards for the shared elements
• The management regulations under the 2007 Regulations (SI 2007/1903), which apply specifically to Section 257 HMOs rather than the 2006 Regulations that cover standard shared houses

The individual flats are still self-contained. Check the applicable local licensing scheme and its standards for any room-size or amenity requirements for converted flats.

The Practical Problem

Many landlords who own converted buildings do not realise Section 257 exists. They check the mandatory HMO threshold — five people, two households, shared facilities — and conclude no licence is needed because each flat is self-contained. That analysis is correct for the mandatory scheme, but it misses the Section 257 route entirely.

If you own a building that was converted into flats and you cannot produce Building Regulations sign-off, check your council's additional licensing scheme before assuming you are exempt.

Our HMO Licensing Guide for England explains how Section 257 HMOs fit within the broader licensing framework and what documentation you need if your council requires a licence for a converted building.

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