Section 257 HMO London — What Counts as a Converted Block?

Section 257 of the Housing Act 2004 defines a specific category of HMO: a building that has been converted into self-contained flats but which does not meet the 1991 Building Regulations and where less than two-thirds of the resulting flats are owner-occupied. The legal test is structural and historic, not occupancy-based.

This category exists because the standard HMO definitions in the Act do not catch converted blocks where each unit appears self-contained. Without Section 257, the long-leasehold pattern of poorly-converted Victorian houses would fall outside HMO oversight entirely despite the fire risk profile of the building.

The classification carries management duties on the building owner (the freeholder or head leaseholder) for the communal parts of the building. It does not require an HMO licence in the same way a Section 254 HMO does, although some boroughs include Section 257 HMOs within additional licensing schemes.

Section 257 was strengthened in enforcement focus after the Grenfell Tower fire and the subsequent fire-safety reforms. Councils are now actively identifying Section 257 buildings and applying management orders where the responsible person has not engaged with the obligations.

A flat is self-contained for Section 257 purposes if it has its own kitchen, its own bathroom or shower room and its own lavatory, all accessed from within the flat. A flat that shares any of these amenities with another flat in the building is not self-contained.

A flat that has been converted from part of a former single-family house but where the bathroom is on a half-landing shared with another flat — common in Victorian terrace conversions — is not self-contained. The shared bathroom takes the building outside the standard 'fully self-contained block' category and into Section 257 if less than two-thirds of the flats meet the self-contained test.

The two-thirds threshold is calculated on the number of units, not floor area. A building with 6 flats where 4 are self-contained and 2 share amenities is 67% self-contained and just over the threshold. A building with 6 flats where 3 are self-contained and 3 share amenities is 50% and clearly within Section 257.

Edge cases — a granny annexe with its own external entrance, an Airbnb sub-let bedroom with shared kitchen, a former HMO partially converted to self-contained but not finished — all need individual assessment. We routinely advise freeholders to commission a formal Section 257 assessment before committing to a building strategy.

The 1991 Building Regulations introduced the modern fire-safety standards for converted flats — fire-resistant separation between flats, protected escape routes through the building, fire-stopping at service penetrations, and the early codification of what became BS 5839-6 alarm coverage. A conversion built to 1991 Regs is structurally adequate to the modern standard.

A conversion completed before 1991 was built to whatever standards then applied — and in most cases that means inadequate fire-resistant separation, no protected escape route and no integrated alarm coverage. Section 257 catches these conversions specifically because they present a different risk profile from a modern build.

Establishing the conversion date requires evidence. Planning records, Building Regulation completion certificates, conveyancing files and freehold management documents all help. Where the conversion was made under 1980s permitted development without formal Building Regs sign-off, the building is presumed pre-1991-compliant.

Post-1991 conversions are outside Section 257 even if some flats share amenities. The 1991 Regs are presumed to have delivered an adequate fire-safety baseline and the building is treated as a standard block of flats for licensing purposes, although Fire Safety Order obligations on communal parts still apply.

Schedule 14 of the Housing Act 2004 sets out the management standards for Section 257 HMOs. The responsible person — usually the freeholder or head leaseholder — must ensure the communal parts are kept in repair, that the means of escape are kept clear, that the fire-safety equipment is maintained, and that the electrical and gas installations in communal parts are tested at appropriate intervals.

Management duty extends to ensuring that information about the responsible person is displayed in the communal entrance — name, contact details and out-of-hours number. This is enforced via the Management of Houses in Multiple Occupation (England) Regulations 2006 as applied to Section 257 buildings.

Failure to comply with management duties is a separate criminal offence from licensing breaches. The Civil Penalty for management failure can be up to £30,000 per breach. Multiple breaches across a building (poor repair, blocked escape, missing alarm coverage, no responsible person notice) can stack into substantial fines.

The duty falls on the freeholder even where the building is managed by a third-party managing agent. The agent acts as the responsible person's delegate but the legal duty remains with the freeholder unless explicitly transferred via the lease terms.

The communal parts of a Section 257 HMO are subject to the Regulatory Reform (Fire Safety) Order 2005. A Fire Risk Assessment (FRA) is mandatory and must be reviewed annually or when material changes occur — refurbishment, change of use, alteration to the escape route.

BS 5839-6 alarm coverage applies in the communal parts. Grade D LD2 coverage is the practical standard — interlinked smoke alarms on every storey landing, heat alarms in any communal kitchen (rare in Section 257 buildings), and CO alarms where any communal combustion appliance is present. The alarm system is the freeholder's responsibility, not the individual flat owners'.

Emergency lighting is required where the escape route lacks adequate borrowed daylight. BS 5266-1 sets the standard — typically two-hour duration self-contained luminaires at every change of direction in the escape route plus one at the final exit.

Communal electrical installation — landlord's supply, lighting, smoke alarms — requires an EICR on a 5-year cycle and a competent person to certify the installation. The communal EICR is separate from any EICR on the individual flats.

Fire doors at every flat entrance opening onto the communal escape route must be FD30 rated and self-closing. This is the single most frequent FRA failure on London Section 257 buildings — original Victorian flat doors that have not been upgraded.

Most London boroughs proactively identify Section 257 buildings from council tax records, Land Registry data and historic planning files. Where a converted-block property is on the council radar, an inspection can be triggered by tenant complaint, fire-and-rescue audit or programmed enforcement visit.

The inspection covers the communal parts only — individual flats are inspected separately under any applicable HMO or selective licensing scheme. The inspector verifies the FRA, the alarm coverage, the emergency lighting, the fire-door condition, the EICR currency and the responsible-person notice in the entrance.

Where deficiencies are found, the council can issue an Improvement Notice requiring works within a specified timeframe (28 days for safety items typically). Failure to comply can escalate to a Civil Penalty or, in serious cases, a Management Order taking control of the communal parts away from the freeholder.

Management Orders are the most serious enforcement tool and are used where the freeholder cannot or will not engage with the obligations. The council appoints an interim manager who takes control of communal repair, fire safety and tenant communications, and recovers costs from the freeholder via charge on the property.

Three common reasons. First, the freeholder bought the building as a 'block of flats' from a previous owner and was never told about Section 257. The legal pack often does not flag it because the test is structural rather than registered. The freeholder assumes block-of-flats rules apply when in fact Section 257 management duties attach.

Second, the conversion was done decades ago and nobody on the current management chain remembers the original state. A Victorian terrace converted in 1975 to four flats with a shared bathroom on the half-landing has been Section 257 for the entire intervening period, but if nobody flagged it at any sale the building has slipped through the regulatory net.

Third, the building has gradually been brought up to standard through refurbishments — kitchens added, bathrooms enlarged, separate amenities provided — but the as-built state is still less than two-thirds self-contained because of one or two flats that never received the upgrade. Partial upgrade does not exit Section 257.

We routinely review converted London blocks against Section 257 as part of compliance audits. The assessment takes a morning and produces a written confirmation of the property's classification. Where Section 257 applies, we follow on with the FRA, the alarm-coverage retrofit and the communal EICR as a single packaged compliance project. Engaging proactively is dramatically cheaper than responding to a council Improvement Notice or, worse, a Management Order.

Lender and insurer scrutiny is also rising. Buy-to-let remortgage applications increasingly ask about HMO classification including Section 257. A freeholder who answers 'no' on the basis of incomplete knowledge is exposed to later allegations of misrepresentation. Buildings insurance underwriters similarly want clarity on the classification — a Section 257 building without an FRA is a substantially worse risk than a fully self-contained block and underwriting reflects that.

For freeholders of converted Victorian and Edwardian London terraces in particular, we recommend a one-time Section 257 assessment as part of any planned refurbishment or remortgage cycle. The assessment costs under £400 and removes the ambiguity that otherwise sits over the building's compliance position for years.