Extending a Ground-Floor Flat: Consents, Design and Planning

Extending a ground-floor flat can add valuable space, but it involves a step that house extensions do not: dealing with the freeholder and, often, other leaseholders. Get the ownership questions right early and the rest of the process runs far more smoothly. Here is how to approach it.

Start with ownership and freeholder consent

Most flats are held on a leasehold basis, and the lease will usually require the freeholder’s consent before any structural work or extension. This is separate from planning permission and just as important — securing the freeholder’s agreement should be your first move, before you invest heavily in design.

Keep other leaseholders informed

If other flats share the building, tell those leaseholders early. Sharing your plans and addressing concerns upfront reduces the chance of objections derailing the process later. With a larger or institutional freeholder, expect a more formal consent procedure.

Design for the space you actually need

Before making a planning application, work with a designer to define what the extension is for — an extra bedroom, a larger kitchen, or more flexible living space — and the best layout to achieve it. An experienced designer balances your needs against the local planning authority’s policies to give the application the best chance.

External design considerations

• Impact on neighbours: size the extension carefully to avoid loss of light or outlook to neighbouring properties and gardens.

• Materials: follow local guidance, especially in a conservation area, and choose materials that sit well with the existing building.

• Drainage and manholes: in terraced properties these are often at the rear; if your extension affects them, budget for diverting pipes with your engineer.

The Party Wall Act

Work to shared walls or close to a boundary usually engages the Party Wall etc. Act 1996, which means serving notice on the relevant neighbours. Handling this correctly and early avoids delays once you are ready to build.

How Studio MASS can help

Our multidisciplinary team guides flat owners through consents, design and planning from start to finish. To discuss your ground-floor flat extension, book a free consultation: email info@studio-mass.com, call 0208 638 6727, or use the Talk to Us button above.

About the author

Robert McBride BSc(Hons) MFPWS is an architectural technologist and director of Studio MASS, a London practice specialising in residential extensions, conversions and new-build homes.