Section 257 HMOs in Hammersmith and Fulham: Converted Flats and Licensing

What a Section 257 HMO Is

Section 257 of the Housing Act 2004 defines a specific type of House in Multiple Occupation that many flat owners do not realise exists. It applies to buildings that have been converted into self-contained flats where two conditions are both met:

1. The conversion did not comply with the Building Regulations in force at the time the work was carried out (the benchmark is the 1991 Building Regulations, or whichever version applied at conversion).
2. Less than two-thirds of the individual flats are owner-occupied — meaning at least one-third are let on private tenancies.

If both conditions apply, the entire building is classified as an HMO under Section 257, regardless of how many people live in any individual flat.

Why It Matters in Hammersmith and Fulham

LBHF explicitly includes Section 257 buildings within its borough-wide additional HMO licensing scheme. That scheme runs until 4 June 2027. If your building is a Section 257 HMO, it needs an additional HMO licence — and the fee is £755 (or £675 with the accredited landlord discount).

Hammersmith and Fulham has a large stock of Victorian and Edwardian houses that were converted into flats decades ago, often without formal building regulation sign-off. Many of these conversions predate the 1991 regulations entirely. If the conversion works were never certified as compliant, and enough of the flats are rented out, the building triggers Section 257.

Who Has to Apply for the Licence

The legal duty to licence a Section 257 building falls on the person having control of or managing the building as a whole. In practice, that is usually the freeholder, the head leaseholder, or the block management company.

The building-level duty sits with the person managing or having control of the block as a whole, often the freeholder, head leaseholder or block management company. A flat owner is not automatically responsible for the building licence simply by owning a flat. If an individual flat is let to tenants on one of the 24 selective licensing streets, it may also need its own selective licence — the building licence and flat licence are separate obligations.

This creates a layered situation: the freeholder needs the additional HMO licence for the whole building, and individual landlords within the building may need separate selective licences for their flats depending on the address and occupancy.

How to Know If Your Building Qualifies

The two questions to answer:

Was the conversion compliant with Building Regulations? The test is whether the conversion complied with the Building Regulations in force at the time. A conversion date or missing completion certificate alone does not establish non-compliance; check which regulations applied and whether the works met them.

Are fewer than two-thirds of the flats owner-occupied? Count the total number of flats in the building, then count how many are occupied by their leaseholder or freeholder (not rented out). If the owner-occupied flats are less than two-thirds of the total, the threshold is met.

In many borough blocks, especially in W6, W12, W14 and SW6, buy-to-let ownership is common enough that the two-thirds test is easily failed.

What Happens If the Building Is Not Licensed

The consequences mirror those for an unlicensed HMO. The maximum civil penalty is up to £40,000. Tenants living in the building can apply for Rent Repayment Orders covering up to 24 months of rent. Section 21 no-fault evictions have been abolished under the Renters' Rights Act.

The practical difficulty is that the person responsible for obtaining the building licence (the freeholder or managing agent) may not even be aware of Section 257. Individual flat owners may need to raise it with the freeholder or management company and push for an application — and if the responsible party refuses, tenants or the council can pursue enforcement.

The Hammersmith and Fulham Landlord Licensing Guide covers Section 257 classification within its licence-decision flowchart and explains how the building-level and flat-level licence obligations interact.

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