Houses in Multiple Occupation (HMOs) — properties let to three or more unrelated tenants sharing facilities — are a significant part of London's rental market. Converting a family house to an HMO can increase rental yield substantially, but the planning, licensing, and building requirements are more complex than standard single-let properties.
Planning Permission for HMO Conversion
In London, almost all HMO conversions require planning permission. A change of use from C3 (dwellinghouse) to C4 (small HMO — 3 to 6 unrelated occupants) was previously permitted development in many areas, but Article 4 directions have been applied by almost every London borough to remove this PD right. Check with your specific borough before assuming PD applies.
Large HMOs (7+ occupants, Sui Generis use class) always require full planning permission.
Planning considerations include:
- Impact on housing mix in the area
- Parking and cycle storage
- Waste and refuse management
- Design and appearance (if external changes are involved)
- Amenity impact on neighbours
HMO Licensing
Mandatory HMO Licensing applies to HMOs with 5 or more persons in 2 or more households sharing facilities, across 3 or more storeys. A mandatory licence must be obtained from the local authority before letting.
Additional HMO Licensing is operated by many London boroughs to cover smaller HMOs (3–4 persons, 2 storeys). Check your borough's licensing scheme — most London boroughs operate additional licensing schemes.
Licence conditions typically specify:
- Minimum room sizes (10m² for a single adult room is the national minimum under the Housing Act 2004 amendment)
- Fire safety standards (fire doors, fire alarm system, emergency lighting)
- Adequate cooking, bathroom, and toilet facilities relative to occupant numbers
- Condition and management standards
Building Regulations for HMO Conversion
A change of use to HMO requires a Building Regulations application. Key requirements include:
Fire safety (Part B):
- Fire alarm system (Grade D minimum, typically Grade A for larger HMOs)
- Fire doors to all rooms (typically FD30S)
- Emergency lighting in escape routes
- Fire stopping where services penetrate compartment walls
Means of escape (Part B):
- Protected escape route from all floors
- Window egress from habitable rooms where applicable
Ventilation (Part F):
- Adequate ventilation in all rooms and shared facilities
Sound insulation (Part E):
- Where internal partitions are created or altered, sound insulation to the revised standards
Typical Costs of HMO Conversion
A full HMO conversion of a 4-bedroom house to a 5–6 bedroom HMO in London typically costs £30,000–£70,000 depending on the existing condition, fire safety works required, bathroom additions, and specification.
rcbGroup
rcbGroup delivers HMO conversion projects across London — from planning and licensing advice coordination through to full construction and Building Regulations compliance.