Barnet Section 257 HMO: Licensing for Converted Flats

Converted Victorian houses, purpose-split terraces and subdivided commercial buildings are everywhere in Barnet. When a building or part of a building converted into self-contained flats did not meet the applicable Building Regulations and still does not meet them, it can be classified as a Section 257 HMO — and that triggers a licensing obligation that many freeholders and head-lessees do not realise exists.

What Makes a Building a Section 257 HMO

Section 257 of the Housing Act 2004 defines a specific class of HMO: a building or part of a building that has been converted into and consists of self-contained flats, where two conditions are both true:

1. The conversion did not comply with the appropriate building standards and still does not comply with them. For conversions completed before 1 June 1992, the relevant standards are those equivalent to the Building Regulations 1991 as they stood on 1 June 1992; for other conversions, they are the requirements in force when the work was done. Common failures include inadequate fire separation between flats, missing fire doors in common areas, insufficient sound insulation and non-compliant escape routes.

2. Less than two-thirds of the self-contained flats are owner-occupied. For this test, a flat counts as owner-occupied when occupied by its freeholder, a person with a lease longer than 21 years, or a member of that person's household. If the building contains six flats and four or more meet this definition, the two-thirds test is met and Section 257 does not apply.

Both conditions must be satisfied. A building where the conversion work passed Building Control — even decades ago — is not a Section 257 HMO regardless of the ownership split.

Why Barnet's Additional Scheme Matters Here

Barnet's borough-wide additional HMO licensing scheme, in force from 27 October 2022 to 27 October 2027, explicitly includes Section 257 HMOs. This means every qualifying converted building across all Barnet wards falls within the licensing requirement.

The licence applies to the building as a whole, not to individual flats within it. A freeholder who owns a converted house containing three rented flats needs one Section 257 licence for the building, not three separate licences.

Individual self-contained flats within a Section 257 building that are let to single households do not need their own HMO licence. But if one of those flats is itself shared by three or more people from two or more households, that flat separately triggers standard HMO licensing in its own right.

Who Holds the Licence

The licence must be held by the person who is most appropriate — typically the freeholder, head-lessee or the entity receiving the rack-rent for the building. If the building is owned by a company, the company itself is named as the licence holder (an individual director cannot hold it in a personal capacity).

Where the freeholder lives abroad, a UK-based managing agent or representative must be appointed as the licence holder or joint applicant.

How the Application Differs

The application follows the same Barnet online portal process as any other HMO licence, with the same two-stage fee structure (£1,061 Stage 1, £811 Stage 2 for a standard five-year licence as of January 2026). The practical differences are:

• Floor plans cover the entire building, not a single flat. Every flat and every common area needs accurate room measurements and layout.
• Safety certificates cover communal parts. Fire alarm certification (BS 5839 Part 6), emergency lighting and communal electrical installations all need current documentation.
• Building Regulations evidence matters. If you can demonstrate that the conversion met the applicable standards — through a Building Control completion certificate or other Building Regulations records — you may be able to show the building falls outside Section 257 altogether.
• The fit-and-proper test applies to the proposed licence holder and manager for the building-level licence. A flat landlord may be assessed separately if their flat itself requires an HMO licence.

Common Traps

Assuming self-contained means exempt. The most frequent mistake is assuming that because each flat has its own front door, kitchen and bathroom, no licence is needed. Self-contained flats inside a non-compliant conversion are exactly what Section 257 covers.

Not checking the conversion history. Many Barnet properties were converted in the 1960s, 1970s or 1980s without Building Control involvement. The absence of a completion certificate does not by itself prove that the conversion failed the applicable standards; check the available Building Regulations records and whether the building still complies.

Ignoring the ownership split. Leaseholders who own and occupy their flats count toward the two-thirds threshold. If the ownership balance shifts (a leaseholder moves out and lets their flat), the building can tip into Section 257 territory.

Planning Is a Separate Obligation

Holding a property licence does not grant planning consent, and planning consent does not replace a licence. If the original conversion to multiple flats was carried out without planning permission, the building may also face planning enforcement. Barnet's housing team will still process the licensing application — public health protection applies regardless of planning status — but the planning enforcement team may pursue the matter separately.

Next Step

If you own or manage a converted building in Barnet and are unsure whether it qualifies as a Section 257 HMO, the Barnet Landlord Licensing guide explains the classification tests, the full document checklist and the step-by-step portal process so you can submit a complete application the first time.

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