HMO Conversions Marylebone

HMO work in Marylebone reflects a stock of flats: the VOA figures for the wider Marylebone & Park Lane and Bryanston & Dorset Square areas put 92% of homes as flats. So it covers flat shares, bedsits and older converted buildings as well as the few houses let room by room. Westminster's borough-wide additional licensing covers shared homes where three or more people from two or more households share a kitchen or bathroom. An HMO project here means fitting a property to Westminster's HMO standards, with fire safety, room sizes and amenities built to what the licence will ask for.

In Marylebone, a light HMO conversion for four to six tenants typically costs £40,000 to £75,000 in construction, or £90,000 to £150,000 with an en-suite to every bedroom (indicative London ranges, Mayfair Studio and LetCompliance, 2026). GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Marylebone: we build the fire doors, detection, bathrooms and kitchens to the council's HMO standards, the landlord applies for the licence, and a registered electrician certifies the electrics.

What an HMO looks like in Marylebone

GOV.UK defines an HMO as a property rented out by at least 3 people who are not from 1 household but share facilities like the bathroom and kitchen. In Marylebone, where flats dominate the housing, that takes in a flat share in a mansion block or a divided townhouse as well as a whole house let room by room. Westminster lists flat shares, bedsits and some converted flats that are not subject to mandatory HMO licensing among the property types its additional licensing covers.

Older conversions are the part owners overlook. Under Westminster's standards, a block of self-contained flats still counts as an HMO if its conversion falls short of the 1991 Building Regulations and long leaseholders hold under two thirds of the flats. Even a building with no shared kitchens or bathrooms can need a licence, Westminster says, where its flats are not all fully self contained. Upgrading fire separation and sound insulation in such a Marylebone building is one kind of HMO work that arises here.

Housing in Marylebone

Marylebone's housing, as the Council Tax list records it, is about 12,620 homes: 8% houses, 92% flats, with 54% pre-1919, 16% interwar and 29% built since 1945.

Planning for a Marylebone HMO: C4, sui generis and Class L

In the London Plan glossary, a shared house for three to six people is Use Class C4, and one for more than six is Sui Generis. Class L of the General Permitted Development Order 2015 lets a C3 home switch to C4 without an application, though a single house cannot be split into two or more C4 HMOs that way. A Marylebone HMO for seven or more sharers therefore needs planning permission, and your designer or agent makes that application.

Permitted development can be removed locally. The London Plan says that when boroughs consider Article 4 Directions affecting changes between C3 and C4, they should weigh the strategic as well as local importance of HMOs, and Policy H9 says HMOs of a reasonable standard should generally be protected. Before relying on Class L for a Marylebone property, your agent should confirm with Westminster whether any direction applies to the address. We build to the planning position they confirm.

Westminster's HMO licensing schemes and a Marylebone let

A Marylebone HMO can fall under one of two licensing tiers. A mandatory licence covers a large HMO, which GOV.UK defines as one rented to 5 or more people who form more than 1 household, although a flat in a purpose-built block of three or more flats falls outside mandatory licensing. Westminster's renewed borough-wide Additional HMO Licensing Scheme dates from a designation on 21 April 2026. It took effect on 31 August 2026 and lasts to 30 August 2031. It follows the first borough-wide scheme, introduced on 30 August 2021, and reaches smaller shared homes across the whole city.

The landlord applies for the licence, and the licence can attach works conditions. Letting an HMO without the licence it needs risks an unlimited fine, according to GOV.UK, and Westminster can also issue a civil penalty. For a Marylebone owner the sensible order is licence position first, then design, then works, because the licence conditions fix the fire, kitchen and bedroom specification we build to. We carry out the works the licence or the inspector asks for and hand over the records for the file.

Room sizes, kitchens and fire safety in a Marylebone HMO

Westminster has produced four sets of HMO standards for different types of multiple occupancy property, updated in April 2021, and it may attach works conditions to a licence to achieve them. For shared houses and flats, the kitchen has to measure 5.5 square metres or more with room for safe use, and a bedroom sleeps two people at most. The national minimums are mandatory licence conditions: 6.51 square metres for one adult, 10.22 for two, and no sleeping in a room under 4.64 square metres. A bedroom under the statutory size must be put right, with Westminster giving 18 months to do so, so layouts are checked at design stage.

Fire safety is the heaviest part of the work. For converted flat buildings, Westminster's standard treats 60 minutes of fire resistance as the building regulations benchmark, yet in most existing conversions it will accept 30 minutes backed by suitable automatic detection. In a shared Marylebone flat or house we fit fire doors with closers, a linked detection and alarm system and a protected escape route, following the LACORS housing fire safety guidance and Part B. Sound insulation between lettings and an EPC of at least E under MEES complete the specification.

• Bedroom layouts checked against the national minimum room sizes
• En-suite shower rooms added to bedrooms
• Large HMO conversions for seven or more, once planning is granted

VOA Council Tax stock of properties, March 2025, for Marylebone & Park Lane and Bryanston & Dorset Square. Counts rounded by the VOA.

If you are weighing up options for your Marylebone property, it is worth reading bathroom renovation in Marylebone, hmo conversions across Westminster, what a main building contractor does, what a kitchen fit covers, how we handle hmo conversions across London and Small Bathroom Ideas.

Trusted HMO Conversions in Marylebone

An HMO is built to pass an inspection, not just to be let. We work from the licence position and the drawings your designer or agent provides, check every bedroom and the shared kitchen against the standards before boarding, and record each fire door, closer and alarm head as it goes in. The electrical and gas certificates and those records form the file a licensing inspector will ask to see, so the house can be let as soon as the works finish.

• Sound lining between bedrooms so one sharer does not keep another awake
• Detection laid out to the grade the council's HMO fire guidance sets
• Aftercare and snagging support once the job is finished

Checked by Abdelaaziz Saaid, founder and director of GS Renovation Ltd (Companies House no. 14611254).