How to turn a house into flats – Key considerations.

Flat Conversions

If you’re a homeowner looking to make a profit from renting or selling your house, converting your property into flats could be a lucrative option.

Splitting your property into two or more units can potentially increase rental income as well as the overall value. This is especially the case in large cities, where flats are in extremely high demand with young professionals and families alike. Complex projects such as these are not without their risks however, making market research and an understanding of costs and legal requirements all the more important.


We’ve compiled the main considerations to bear in mind when converting houses into flats – to help your project get off to the best possible start.

How to turn a house into flats - Market research

Market Research.

If you are currently considering converting your house into flats, make sure you’ve undertaken some thorough market research to determine demand for flats in your area.

Talk to estate agents if possible and try to find out who is renting or buying properties in your area, as well as what requirements they are looking for – i.e. number of bedrooms, outside spaces and living areas.


Consider whether renting or selling would maximise your profits, as often tenants will seek properties close to local amenities and transport links, whereas families purchasing homes will prize proximity to good schools.


If you don’t own a property yet and are still searching for that perfect house to convert, make sure to keep an eye on up-and-coming locations. Inform your solicitor that you plan to convert the property, as there may be legal barriers to creating separate households such as caveats in the deeds. You should also discuss plans with your lender, as your mortgage may be affected by sub-dividing the property. Other funding opportunities are available including refurbishment or development loans – but whatever route you choose, researching all available options will be key.

Turning a house into flats - planning permission

Planning Permission.

You will require planning permission to divide your house into multiple units, with further permissions required if it is a listed building, requires any demolition work or is located within a conservation area.

The Town and Country Planning Act 1990 defines the subdivision of a dwelling into two or more separate dwellings as a “material change of use” needing planning permission. Since 2010 however, the conversion of a single dwelling into two separate units was deemed “permitted development” for up to 6 people.

Despite this.

Many councils have removed such permitted development rights, dependent on density and the impact on existing communities.


It is always worth talking to local council in the first instance, who will require details such as existing plans, proposed changes and any effect on access, parking and waste collection.

If the alterations impact the external elevations of a property, this information will also be required in the application. When it comes to applying for planning permission, it is best to seek professional guidance. Local architects will have experience with the processes and know what planners are looking for – from minimum space standards to access requirements and services provision for conversions.

Practical considerations

Practical Considerations.

Do you have enough space to convert your house to flats – and is your property suitable for conversion in the first place?

A successful change of use will rely on practicalities such as clear divisions, soundproofing, access and all the necessary sanitary provisions. Many of these changes will be covered by building regulations, so spending time getting your plans right, working with architects and trusted building contractors will pay off in the long run. These requirements provide set standards for factors such as insulation, lighting, alarms, fire safety measures including doors and escape routes, and minimum room/flat sizes.

In addition.

You will need to make sure that you have spoken to utility companies, as self-contained units require separate supplies of gas, water, electric and sanitary services.

Again there are strict rules on the route and installation of such services and a survey by a qualified engineer will determine the practicality of this. This may all come with additional costs to bear in mind. There may also be tax implications – for instance, if you’re converting your property to maximise profit, any such profits could be charged to income tax as trading profits (as opposed to capital gains tax). Do make sure to work with a qualified solicitor, who will be able to provide advice on this.

Turning a house into flats - costs and profits

Costs and Profits.

One of the most important factors when converting your house into flats is the associated costs. Can you afford all of the work required, and once complete – will you make a profit on the development?

Sub-dividing can be a complex process and your builders may have to install additional bathrooms, kitchens, and plumbing. Make sure to ask for detailed quotes from building firms, checking whether this includes installation and appliances. You should also consider design costs, the existing condition and size of the building, the number of flats you’ll be converting as well as heating, boilers, soundproofing and utility installations.


Planning permission, building regulations and legal fees will all also have to be budgeted for. As a rule of thumb, if the existing building is structurally sound and the existing bathrooms and kitchen can be used – a basic conversion may start at around £25,000.

Each project will vary, but this can easily range to £100,000 or more depending on the complexity of your build and level of finish required. Your builder will also be able to advise on timescale for the project, but you should expect such conversions to take at least six months. Factoring in these expenses will make sure your conversion doesn’t end up costing you money in the long run.

Final thoughts.

Commencing any conversion project can be a time-consuming but ultimately rewarding task. When thinking about turning your house into flats, be sure to do your research beforehand – and make sure that the refurbishments are financially worthwhile as well as practically possible. With the help of professionals and a thorough understanding of the costs and legal requirements, you’ll be off to the best possible start. Good luck, and happy converting!

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EV Architects is a London-based architectural practice that provides a comprehensive range of architecture, design and planning services for a broad range of property development projects, including flat conversions.

Visit our Flat Conversion service page to find out more, or call us on 020 8531 4441 for a no-obligation chat with one of our Architects today.