architects FROM LONDON House-to-Flats Conversions
Convert a House Into Well-Planned Separate Flats
↓
RIBA Chartered
Award winning
London · Vienna · Rome
Featured in The Times
Panel at Grand Designs Live
House-to-Flats Conversions intro
Convert a House Into Well-Planned Separate Flats
Converting a house into flats can create multiple homes within an existing property, but the success of the project depends on far more than simply dividing the floor plan.
The new flats need to work independently, with suitable access, natural light, privacy, storage, kitchens, bathrooms, fire safety and acoustic separation.
At Tholos Architects, we design house-to-flats conversions around both the existing building and the requirements of each new dwelling so the final result feels properly planned rather than compromised.
A house-to-flats conversion can help you:
- Create multiple independent homes
- Make better use of a large property
- Reorganise underused floor area
- Create rental accommodation
- Improve internal layouts
- Upgrade fire safety
- Improve acoustic separation
- Modernise services
- Improve energy performance
- Coordinate planning and Building Regulations
The aim is to create flats that feel like complete homes in their own right.
House-to-Flats Conversions explained
What Is a House-to-Flats Conversion?
A house-to-flats conversion involves dividing one residential property into two or more separate dwellings.
This may create:
- Two flats
- Several flats
- Maisonettes
- Ground-floor and upper-floor flats
- A mixture of different unit sizes
Each new dwelling generally needs its own:
- Kitchen
- Bathroom
- Living space
- Bedrooms where applicable
- Access
- Services
- Fire separation
The layout needs to be designed so the individual flats work independently while still fitting comfortably within the existing building.
Why Convert a House Into Flats?
Some houses are large enough to accommodate more than one dwelling.
A conversion may be considered where:
- The property is unusually large
- The existing layout is inefficient
- Demand is stronger for smaller homes
- The building already has multiple floors
- Separate entrances can be created
- The owner wants to create rental units
However, the number of possible flats should be driven by the building rather than simply maximised.
Creating fewer, better-planned flats can often produce a stronger result than forcing too many units into the property.
How Many Flats Can a House Become?
This depends on the size, layout and planning context of the property.
Important factors include:
- Total floor area
- Number of floors
- Existing windows
- Staircase position
- Front and rear access
- Room proportions
- Natural light
- Local planning policy
- Parking and cycle requirements
- Refuse storage
A large house may work well as two generous flats but poorly as four small ones.
The feasibility should be tested through layout options before the number of units is fixed.
House-to-Flats Conversions options
Converting a House Into Two Flats
A two-flat conversion is one of the most common arrangements.
Possible layouts include:
- Ground-floor flat + upper-floor flat
- Lower-ground flat + upper maisonette
- Ground-floor flat + first-and-second-floor maisonette
This can work particularly well where the property already has:
- Separate front and rear access
- Several storeys
- Generous floor area
- Good natural light
Each flat should still have a clear sense of privacy and independence.
Ground-floor and Upper-floor Flats
One simple approach is to divide the property horizontally.
The ground floor may become one flat while the upper floors form another.
The design needs to consider:
- Separate entrances
- Shared hallway
- Stair access
- Acoustic separation
- Fire separation
- Metering
- Storage
The ground-floor flat may also have access to the garden, depending on the layout.
Maisonette Conversions
Where a house has several floors, one or more of the new dwellings may work better as maisonettes.
A maisonette can provide:
- Bedrooms on one floor
- Living space on another
- More separation between rooms
- Better use of upper floors
This can be particularly useful in taller Victorian and Edwardian houses.
Separate Entrances
Separate entrances can significantly improve privacy.
Depending on the building, this may involve:
- Retaining one shared entrance
- Creating a new side entrance
- Creating a rear entrance
- Reconfiguring the hallway
- Adding an external stair in some cases
The entrance arrangement needs to work with:
- Fire safety
- Security
- External appearance
- Planning
Shared Entrance Halls
A shared entrance can also work well.
The common area needs to provide:
- Secure access
- Safe circulation
- Good lighting
- Appropriate fire separation
- Postal arrangements
- Access to meters
Shared spaces should be kept simple and easy to maintain.
Living Room Design
Each flat should have a practical living space.
The layout should consider:
- Furniture
- Natural light
- Privacy
- Circulation
- Relationship with the kitchen
- Storage
Where possible, living rooms should avoid becoming circulation spaces to other rooms.
Kitchens
Each independent flat normally requires its own kitchen provision.
The kitchen design needs to consider:
- Worktop space
- Appliances
- Storage
- Ventilation
- Drainage
- Natural light
- Relationship with living areas
Existing plumbing locations can influence the design, but the layout should not be driven by services alone.
Bathrooms
Each flat also needs suitable bathroom provision.
Depending on size, this may include:
- Bathroom
- Shower room
- En-suite
- Separate WC
The position of bathrooms should consider:
- Drainage
- Ventilation
- Acoustic separation
- Privacy
- Floor structure
Stacking bathrooms between floors can sometimes simplify drainage and services.
The position of bathrooms should consider:
Bedrooms
Bedrooms need to be designed around practical use.
Important considerations include:
- Bed position
- Wardrobe space
- Natural light
- Privacy
- Room proportions
- Circulation
Awkward leftover spaces should not simply be labelled as bedrooms if they do not function properly.
House-to-Flats Conversions
Natural Light
Natural light is critical in house-to-flats conversions.
Each dwelling should have suitable daylight to its main rooms.
The design may need to consider:
- Existing windows
- New windows
- Rooflights
- Lightwells
- Internal layout
Deep internal rooms with little daylight may need to be used for:
- Bathrooms
- Storage
- Circulation
rather than principal living spaces.
Privacy
Dividing one house into several homes introduces new privacy considerations.
The design should consider:
- Entrance arrangements
- Window positions
- Garden use
- Shared circulation
- Sound transmission
Ground-floor flats may need additional privacy where windows face directly onto streets or shared paths.
Acoustic Separation
Sound insulation becomes particularly important when one house is divided into separate dwellings.
Noise can transfer through:
- Floors
- Walls
- Staircases
- Service penetrations
- Doors
The conversion may need upgraded:
- Floor construction
- Ceilings
- Party walls
- Internal walls
Proper acoustic separation can significantly improve the quality of the finished flats.
Fire Safety
Converting one house into multiple dwellings changes the fire safety strategy.
Requirements may include:
- Fire-resistant walls and floors
- Protected escape routes
- Fire doors
- Smoke detection
- Compartmentation
- Emergency lighting in shared areas
The exact strategy depends on the number of units, number of floors and layout.
Staircases and Circulation
The existing staircase often becomes a central part of the conversion.
It may need to serve:
- Shared access
- Upper flats
- Escape routes
The design may require:
- Fire protection
- New landings
- Door changes
- Altered circulation
Where possible, the existing staircase should be used efficiently without creating awkward access into the new dwellings.
Structural Changes
House-to-flats conversions can require structural alterations.
This may include:
- Removing walls
- Creating new openings
- Adding beams
- Forming new entrances
- Altering stairs
- Strengthening floors
Any structural work should be coordinated with the new layout.
Drainage and Plumbing
Creating several homes increases the number of:
- Kitchens
- Bathrooms
- WCs
- Sinks
- Waste connections
The drainage design needs to be coordinated carefully.
This may involve:
- New soil stacks
- New waste pipes
- New drainage runs
- Separate service connections
Heating and Utilities
Each flat may require separate or individually controllable services.
This can include:
- Heating
- Hot water
- Electricity
- Gas
- Water
- Metering
The services strategy should be established early because it can affect plant space and internal layouts.
Refuse and Recycling Storage
Multiple dwellings generate different refuse requirements from a single house.
The design may need to provide space for:
- General waste
- Recycling
- Food waste
Bins should be located where they are:
- Accessible
- Practical
- Visually discreet
Planning authorities may consider refuse storage as part of the application.
Cycle Storage
Cycle storage may also need to be provided.
Possible solutions include:
- Front garden storage
- Rear garden storage
- Internal cycle stores
- Secure external stores
The correct solution depends on the property and local planning requirements.
Garden and Outdoor Space
Where the existing house has a garden, the conversion should consider how outdoor space will be used.
Options may include:
- Garden allocated to ground-floor flat
- Shared garden
- Divided garden
- Private terraces
The arrangement should be clear and practical for future residents.
Parking
Parking requirements vary significantly by location.
The planning authority may consider:
- Existing parking
- On-street conditions
- Number of new dwellings
- Public transport accessibility
- Local parking standards
The conversion should be assessed within its specific local context.
House-to-Flats Conversions
Do You Need Planning Permission to Convert a House Into Flats?
Usually, yes.
Dividing a single house into separate independent dwellings is generally a material change of use and typically requires planning permission.
The local authority may consider:
- Number of units
- Flat sizes
- Local housing mix
- Parking
- Refuse
- Cycle storage
- External alterations
- Neighbouring amenity
The planning position should be assessed before the internal layout is finalised.
Local Planning Policies
Many councils have specific policies covering conversion of houses into flats.
These may consider:
- Minimum dwelling size
- Bedroom sizes
- Retention of family housing
- Local concentration of flats
- Amenity space
- Parking
- Waste storage
- Cycle storage
A layout that works physically may still conflict with local planning policy.
This is why policy review should happen early.
External Alterations
The conversion may require external changes such as:
- New front door
- Side entrance
- Rear entrance
- New windows
- Rooflights
- Bin stores
- Cycle stores
These should be designed to integrate with the existing building.
House-to-Flats Conversions in Conservation Areas
Conversions within conservation areas may need additional care.
Planning authorities may pay particular attention to:
- New entrances
- Windows
- External stairs
- Bin storage
- Cycle storage
- Historic character
Internal subdivision may be less visible, but the external consequences still need careful design.
Listed Buildings
A listed house may potentially be divided into flats, but alterations to historic fabric can require Listed Building Consent.
This may affect:
- New partitions
- Staircases
- Doors
- Fire protection
- Services
- Structural changes
The design needs to balance residential requirements with conservation of significant features.
Building Regulations
House-to-flats conversions generally require Building Regulations approval.
Requirements may include:
- Fire safety
- Acoustic performance
- Structural safety
- Ventilation
- Drainage
- Electrical work
- Insulation
- Stairs
- Glazing
The conversion usually involves more technical coordination than a straightforward internal refurbishment.
House-to-Flats Conversion vs HMO
A house divided into self-contained flats is different from a House in Multiple Occupation.
In self-contained flats, each dwelling normally has its own:
- Kitchen
- Bathroom
- Living accommodation
An HMO may involve residents sharing some facilities.
The planning, licensing and Building Regulations implications can therefore be different.
It is important to establish the intended use clearly before design work begins.
House-to-Flats Conversion vs Flat-to-House Conversion
A house-to-flats conversion divides one property into several dwellings.
A flat-to-house conversion does the opposite by combining separate units back into one home.
House-to-Flats Conversion
House-to-Flats Conversion Process
1. Assess the Existing House
We begin by reviewing:
- Floor area
- Number of storeys
- Existing layout
- Staircase
- Windows
- Access
- Services
- Planning context
2. Review Planning Policy
We assess:
- Local conversion policies
- Housing mix
- Parking
- Amenity
- Unit standards
- Conservation considerations
3. Test Different Layouts
We consider:
- Number of flats
- Unit sizes
- Bedroom numbers
- Entrances
- Shared circulation
- Garden arrangements
4. Coordinate Fire and Acoustic Design
We consider:
- Escape routes
- Fire separation
- Fire doors
- Sound insulation
- Shared areas
5. Coordinate Structure and Services
This may include:
- New openings
- Drainage
- Heating
- Metering
- Electrical systems
6. Submit the Planning Application
The application can include:
- Existing drawings
- Proposed drawings
- Supporting design information
- Other required documentation
7. Develop the Building Regulations Design
The technical design is then coordinated for:
- Fire
- Acoustics
- Structure
- Ventilation
- Insulation
- Drainage
8. Prepare for Construction
Detailed drawings can then be produced so builders can accurately price and construct the conversion.
Client experience
"
Lorem ipsum dolor sit amet, consectetur adipiscing elit. We had a vision for our home but no idea how to realise it. Tholos Interiors took complete ownership of the project — every detail was considered, every decision explained. The result exceeded everything we had imagined.
– Lawrence Ipsum, Homeowner · London –
Frequently Asked Questions
Can I divide my house into two flats?
Potentially, yes.
The property needs to be suitable physically and the proposal must satisfy the relevant local planning policies.
Do the flats need separate utilities?
Separate or independently controlled services are often desirable and may be required depending on the system and project.
Do I need sound insulation between flats?
Yes, acoustic separation is an important Building Regulations consideration when creating separate dwellings.
Can I create three or more flats?
Potentially.
The number of flats depends on the property size, layout, planning policy and technical requirements.
Create Separate Homes That Work Properly
Dividing a house into flats can unlock significant potential, but the project needs to work at both planning and technical level.
Each new dwelling should feel like a proper home, with good natural light, privacy, storage, safe access and appropriate separation from neighbouring units.
At Tholos Architects, we can help you assess how many flats the property can reasonably accommodate and develop the planning and technical drawings required to take the project forward.
Disclaimer
This article is part of a series created by our dynamic marketing team for informational purposes only. While we strive to review all content thoroughly, occasional oversights may occur, even after publication. Therefore, we cannot accept liability for any interpretations or use of the information provided. For the most up-to-date information or to report any discrepancies, please contact us at hello@tholos-architects.com.
Start your project