The Ultimate Guide to Flat Conversions
Converting a house into flats in the UK can be a lucrative way to maximise rental income and help address housing shortages. However, the process involves complex planning and building regulation considerations, as well as increasing scrutiny from local authorities seeking to preserve family housing stock. This article offers a detailed guide for property owners, developers, and investors on what to consider when undertaking such a conversion.
1. Understanding the Basics of Converting a House into Flats
What Does Conversion Entail?
Converting a house into flats typically involves subdividing a single dwelling into two or more self-contained units. Each flat will usually have its own kitchen, bathroom, and living area.
This can be appealing in dense urban areas where rental demand is high, but the legal and regulatory process is becoming more stringent, especially in relation to the loss of smaller family homes.
2. Planning Permission: A Critical First Step
Do You Need Planning Permission?
In most cases, yes. Converting a house into multiple flats is classified as a “material change of use” under the Town and Country Planning Act 1990. This means you generally need full planning permission from your local planning authority (LPA).
Exceptions
• Permitted Development Rights (PDRs): Some commercial-to-residential conversions can proceed under PDRs, but PDRs do not apply to the conversion of single dwellings into flats.
• Article 4 Directions: Local authorities may issue Article 4 Directions removing PDRs to control the proliferation of flat conversions in certain areas.
Pre-application Advice
It’s wise to seek pre-application advice from the local planning department. This can highlight policy obstacles, such as family housing protection zones, before committing to design or purchase decisions.
3. Key Planning Considerations
Local Development Plans
Planning decisions are guided by each council’s Local Plan. Many LPAs now include specific policies aimed at restricting the conversion of small or medium-sized family homes, particularly in areas where the availability of such housing is under pressure.
Loss of Family Housing
A growing number of councils (e.g. in London boroughs, Birmingham, Manchester, and Bristol) are implementing policies to retain family-sized dwellings—typically homes with three or more bedrooms, gardens, and off-street parking.
These policies often:
• Presume against converting houses under a certain size or with fewer than a minimum number of bedrooms.
• Require justification that the area is not in deficit of family housing.
• Designate Family Housing Retention Areas, where conversions are prohibited or heavily discouraged.
Tip: Always check your LPA’s policy on protecting family housing. Attempting to convert a small terraced or semi-detached house into flats in such areas is likely to be refused.
Housing Density and Mix
• Is the area already saturated with flats?
• Will the development diversify or distort the housing mix?
Amenity Space
• Private or communal outdoor space may be required.
• Internal space must meet national minimum standards (see Section 4).
Parking and Transport
• Adequate off-street parking may be required.
• Parking stress assessments may be needed in urban zones.
Bin and Bicycle Storage
Many councils insist on:
• Secure and accessible cycle storage.
• Adequate refuse and recycling facilities screened from view.
Access and Layout
• Each flat must have its own safe and practical access.
• Communal hallways and stairs must comply with fire and building safety requirements.
4. National Minimum Floor Area Standards
National Space Standards (NDSS)
Introduced by the government in 2015, the Technical Housing Standards – Nationally Described Space Standard (NDSS) defines the minimum internal space requirements for new dwellings, including those created via conversion.
Many councils have adopted these as part of their Local Plan policies, making them a requirement for planning approval.
Key NDSS Minimum Space Standards
Dwelling Type No. of Bedrooms Occupants Minimum Gross Internal Area (GIA)
1-storey flat 1 1 39 m² (with shower only)
1-storey flat 1 2 50 m²
1-storey flat 2 3 61 m²
1-storey flat 2 4 70 m²
1-storey flat 3 5 86 m²
Other NDSS Requirements
• Floor-to-ceiling height of at least 2.3 metres over 75% of the GIA.
• Minimum built-in storage of 1–2.5 m², depending on dwelling size.
• A single bedroom must be at least 7.5 m² and 2.15m wide.
Important: Even if your proposed flats comply with building regulations, failure to meet NDSS standards may result in a planning refusal if your local authority has adopted them.
5. Building Regulations and Compliance
Regardless of planning approval, building regulations approval is mandatory.
Main Building Regulation Areas
Fire Safety (Part B)
• Fire doors and fire-rated partitions
• Smoke and heat detectors
• Protected escape routes and emergency lighting
Sound Insulation (Part E)
• Soundproofing between walls and floors
• Acoustic testing may be required unless robust details are used
Ventilation (Part F)
• Mechanical or passive ventilation systems for kitchens, bathrooms, and living areas
Drainage and Waste Disposal (Part H)
• Separate drainage for each unit
• New or modified soil stacks and sewer connections may be needed
Electrical and Gas Safety
• Independent metering and compliance with Part P (electrical safety)
• Work must be carried out by qualified professionals
Utilities and Services
• Each flat should ideally have:
• Separate gas, water, and electricity meters
• Individual boilers and heating systems (or shared if well-managed)
6. Structural Alterations
Conversions often involve:
• New internal walls and floors
• Removal of load-bearing walls
• Reinforcement of floors to support additional loads
A structural engineer’s input will likely be required to meet Part A (Structure) of the Building Regulations.
7. Party Wall Act 1996 Considerations
If your works affect shared or adjoining walls (common in terraced and semi-detached houses), you must comply with the Party Wall Act 1996:
• Serve notice to adjoining owners.
• Possibly appoint party wall surveyors to agree on a Party Wall Award.
8. Licensing and Legal Compliance
HMO Licensing
If your conversion results in shared accommodation (e.g. 3 or more tenants forming 2+ households), it may qualify as a House in Multiple Occupation (HMO). This can require:
• Mandatory licensing (for large HMOs)
• Additional licensing schemes (in many urban councils)
HMO properties must meet standards for:
• Room sizes
• Fire safety
• Amenities (e.g. bathrooms, kitchens)
Leasehold Considerations
• If the property is leasehold, freeholder consent may be needed for structural changes.
• If selling individual flats, you’ll need to grant leases and possibly form a management company to hold the freehold.
9. Financial and Tax Implications
Council Tax
Each unit will usually receive its own council tax band, possibly increasing total outgoings.
Capital Gains Tax (CGT) and Stamp Duty (SDLT)
• CGT implications if you sell the flats individually.
• SDLT surcharges may apply to second or additional homes.
VAT
Conversions may be eligible for reduced or zero-rated VAT treatment in some circumstances—check with a tax advisor.
10. Practical and Professional Support
Professionals You’ll Need:
• Architectural designer
• Planning consultant (strongly advised if converting in a restricted area)
• Structural engineer
• Building surveyor
• Solicitor
• Accountant or tax advisor
• Approved building inspector
Budgeting and Project Management
Conversions typically cost £25,000–£80,000+ per unit, depending on complexity, standard of finish, and location. Always factor in a 15–20% contingency.
Conclusion
Converting a house into flats in the UK is not just a matter of design and cost—it’s a matter of navigating increasingly strict planning and housing policies. With a national shortage of affordable family homes, many councils are restricting the conversion of smaller houses to protect the availability of family housing stock.
Even where a conversion seems technically viable, it may face planning refusal based on local policies aimed at preserving family dwellings, or for failure to meet national space standards.
Careful planning, early engagement with your local authority, and professional advice are essential to avoid costly delays, refusals, or enforcement action.
Disclaimer: This article is for general informational purposes only and does not constitute legal or professional advice. Always consult relevant professionals and local authorities before undertaking any development or change of use.