Loft conversions in Sussex

For many homes, the loft is the largest unused space in the house. Converting it can add a bedroom, bathroom, home office or playroom without giving up any of your garden. Fill in one short form or call 01273 115520, and up to 3 checked local builders who take on loft conversions will be in touch to arrange a visit and a quote. The service is free and there is no obligation. If your loft is not suitable, a home extension or garage conversion may be a better fit.

Loft conversion prices

Loft conversion costs depend mainly on the type of conversion and its size. No source we use gives prices for Sussex specifically, so the table below shows Checkatrade's national figures for a 30m² conversion. MyJobQuote gives a separate national average of £40,000 for a loft conversion in 2026.

These are significant sums, which is why comparing detailed quotes from more than one builder matters. Our loft conversion cost guide compares figures from several sources and explains what is usually included.

Loft conversions in Sussex: types, costs and planning

Loft conversions are a popular way to add living space to a Sussex home because they use room already inside the roof rather than building out into the garden. The best type for your house depends on the roof shape, the pitch and the headroom you have to start with. Terraced houses often suit a rear dormer, while semi-detached and detached houses with hipped roofs are common candidates for a hip-to-gable conversion.

Cost varies with the type of conversion. Checkatrade puts a 30m² Velux conversion, which adds roof windows without changing the roof structure, at an average of £27,500. A dormer creates much more usable floor space, and Checkatrade gives an average of £50,000 for a 30m² dormer. A hip-to-gable conversion, which replaces the sloping end of a hipped roof with a vertical gable, averages £60,000 on the same basis. MyJobQuote lists structural engineer fees of £600 to £1,800 and party wall surveyor fees of £800 to £1,000 as possible extras, so ask each builder what their quote includes.

Many loft conversions are permitted development. The Planning Portal says the additional roof space must not exceed 40 cubic metres for a terraced house or 50 cubic metres for other houses, must not be higher than the existing roof and must not extend beyond the roof slope on the front of the house facing a highway. These rights do not apply to flats or buildings containing flats, or to homes in conservation areas, and rules differ again for listed buildings and maisonettes. Where you need a householder planning application, GOV.UK sets the fee in England at £548 from 1 April 2026.

Building regulations are a separate approval from planning. Turning a loft into a habitable room is building work that needs to meet the regulations, and you can use your council's building control service or a private registered building control approver. Charges vary by council, and permission is never guaranteed, so check with your local planning authority and building control before you commit.

Sources for the prices on this page

• Checkatrade: Loft conversion cost 2026 UK price guide, checked October 2026
• MyJobQuote: How much does a loft conversion cost in the UK? (2026), checked October 2026
• GOV.UK: Fees for planning applications in England from 1 April 2026, checked October 2026