House-to-flat conversions: Costs & Planning

What is a house-to-flat conversion?

A house-to-flat conversion divides a single house into two or more self-contained flats, each with its own front door, kitchen and bathroom. It always needs planning permission and full building regulations approval, particularly for fire separation and sound insulation between flats.

Large Victorian semi-detached villa converted into flats with separate entrances and bin store

We assess the house against the council’s policies on flat sizes, parking, bins and cycle storage before any design work, then design layouts to the space standards your council uses. On site the critical work is fire separation, sound insulation between floors, separate services and meters, and protected escape routes.

Typical time on site: 16 to 30 weeks
Guide price: Priced on survey
Building regulations: Required

What is included?

Feasibility check against local planning policy
Planning application and layouts to space standards
Fire separation and sound insulation between flats
Separate electrics, heating and metering
Kitchens, bathrooms and finishes
Bin, cycle and amenity space works

How much does a house-to-flat conversion cost?

Costs depend heavily on the house, the number of flats and how much existing structure can stay. We price each conversion on survey and set out every element in writing. Qualifying conversions that change the number of dwellings can benefit from the reduced 5% VAT rate.

Priced on survey. Costs depend heavily on the house, the number of flats and how much existing structure can stay. We price each conversion on survey and set out every element in writing. Qualifying conversions that change the number of dwellings can benefit from the reduced 5% VAT rate.

Use the guide price tool for a figure based on your size and specification, or see all guide prices.

Does a house-to-flat conversion need planning permission?

England

Dividing a house into flats always needs planning permission in England. Councils assess flat sizes (many use the nationally described space standard), parking, bins, cycle storage and the effect on family housing supply.

Wales

This needs full planning permission from your council in Wales. We prepare and submit the application and deal with the planning officer on your behalf.

Scotland

This needs planning permission and a building warrant from your council in Scotland before work starts. We prepare both applications.

Northern Ireland

This needs full planning permission from the council in Northern Ireland, plus building control approval.

What about building regulations?

Full building regulations approval, with particular focus on fire separation, means of escape, sound insulation and separate services.

What should I think about before starting?

Some councils restrict the loss of family houses or limit flat conversions in certain streets.
Each flat needs its own utilities and metering.
Sound insulation between flats is tested on completion.
Mortgage lenders and freehold arrangements need early legal advice.

How does the project run?

Tell us about the project. Call, use the guide price tool or send the form with a few photos and a postcode.
Free site visit. We measure up, look at access, drains and the structure, and talk through options and budget.
Design and fixed price. You get drawings and a written price for the agreed specification before anything is ordered.
Build and hand over. Our teams build to the programme, building control inspects, and you get the completion paperwork at the end.

Questions about house-to-flat conversions

Does converting a house into flats need planning permission?

Yes, always. Subdividing a house into flats is development under planning law.

How much does a flat conversion cost?

It varies too much to give a reliable guide figure, so we price each one on survey. The reduced 5% VAT rate can apply where the number of dwellings changes.

What are the main building regulations issues?

Fire separation between flats, protected escape routes, sound insulation and separate services.

How long does a conversion take?

Typically 16 to 30 weeks on site after approvals.

Can you help with the planning case?

Yes. We check the council’s policies first and only proceed with a design that has a realistic chance of approval.

Related projects

Guides

What VAT rate applies to building work on my home?

Where do we build house-to-flat conversions?

We take on house-to-flat conversions across England, Wales, mainland Scotland and Northern Ireland. Choose your area: