Lambeth Section 257 HMOs: Licensing Rules for Converted Flats

Converted Victorian and Edwardian houses are everywhere in Lambeth. If a building was split into self-contained flats without meeting the Building Regulations in force at the time of conversion, the whole building can be classified as a Section 257 HMO — and that triggers licensing obligations most flat owners never see coming.

What Makes a Building a Section 257 HMO

Under Section 257 of the Housing Act 2004, an entire building counts as an HMO if two conditions are both true:

1. The building was converted into self-contained flats and the conversion did not comply with the Building Regulations 1991 (or whichever standard applied at the time) — and still does not comply.
2. Fewer than two-thirds of the individual flats are owner-occupied.

A Victorian terrace in Herne Hill split into four flats in 1985 meets condition one if the conversion did not comply with the appropriate building standards and still does not. If three of those four flats are not owner-occupied, condition two is also satisfied. The building is a Section 257 HMO.

Lambeth's Additional HMO licensing scheme, which runs borough-wide until 8 December 2026, explicitly covers Section 257 HMOs. The freeholder or head lessee who controls the common parts — stairwells, hallways, shared entrance — must hold a Section 257 Additional HMO licence for the building itself.

Who Actually Needs to Apply

The person responsible for the Section 257 licence is whoever controls the common parts of the building. Usually that is the freeholder or head lessee. Individual flat leaseholders who only control their own flat are not responsible for the building-level licence.

But individual flats within the building still need their own licences depending on how they are let:

• A flat let to a single household in one of the 23 selective licensing wards needs an individual selective licence (the flat owner applies).
• A flat let to three or four unrelated sharers needs an individual additional HMO licence.
• A flat let to five or more people from two or more households needs a mandatory HMO licence.

The building-level Section 257 licence and the individual flat-level licences run in parallel. A flat owner might hold a selective licence for their unit while the freeholder holds a Section 257 licence for the building.

How to Check Whether Your Building Qualifies

Check the conversion work against the appropriate building standards. For work completed before 1 June 1992 (and not exempt under the 1991 Regulations), the standard is equivalent to those Regulations as they stood on that date; for other conversions, it is the requirements in force under regulations made under the Building Act 1984 at the time. The work must both have failed to meet those standards and still fail to meet them; the date or missing sign-off alone does not decide the test.

Then count owner-occupied flats using Section 257's definition: a flat counts if occupied by someone with a lease of more than 21 years, the person with the freehold estate in the converted block, or a member of that person's household. If fewer than two-thirds of the flats meet that definition, condition two is met.

Lambeth's licensing portal at hmolicensing.lambeth.gov.uk handles Section 257 applications through the Additional HMO route. Lambeth charges for a Section 257 application per self-contained flat.

What Happens If the Building Is Not Licensed

The freeholder or head lessee operating a Section 257 building without the required licence faces the same enforcement as any unlicensed HMO: civil penalties up to £40,000 per offence (since the Renters' Rights Act amendments took effect on 1 May 2026) and potential rent repayment orders covering up to 24 months of rent.

Individual flat owners are not liable for the building-level licence — but they are liable for their own flat-level licence if one is required.

For Lambeth landlords dealing with converted buildings, our Lambeth Landlord Licensing Guide walks through every scheme side by side, including the Section 257 decision logic and fee calculations for each licence type.

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