Dormer Loft Conversion

A dormer loft conversion is the most popular type we carry out in Worthing and across West Sussex — and with good reason. It's a box-shaped extension that projects vertically from the slope of your existing roof, adding a full-height wall and a flat or low-pitch roof section. The result is dramatically more usable floor space than the original loft, with proper standing height throughout the new room.

Structurally, a dormer works by cutting an opening in the existing roof slope and building outward. The dormer walls are typically timber-framed and clad in matching render, tile hanging or zinc, depending on what suits the property. The flat roof section is usually finished with a modern GRP (fibreglass) membrane, which requires minimal maintenance and carries a long guarantee. Rooflights or large windows on the front face of the dormer bring in plenty of natural light.

Dormers are particularly effective on semi-detached houses, terraced properties and detached homes with a suitable rear or side roof slope. The conversion typically creates a large bedroom — often with space for a properly fitted en-suite bathroom — plus built-in storage under the eaves on either side. Many of our clients in areas like Durrington, Broadwater and Findon Valley have used dormer conversions to create a primary bedroom suite that transforms how the whole house is used.

From a structural engineering perspective, the loft floor joists need to be strengthened to carry the weight of a habitable room. We install new floor joists alongside the existing ceiling joists, ensure the ridge and rafters are properly supported, and fit the steel beam or timber ridge beam required to carry the new dormer structure. All structural calculations are provided by a qualified engineer and submitted to building control.

Planning permission is not always required for a rear dormer — many fall within permitted development rights, particularly in standard residential streets. However, properties in conservation areas, those with Article 4 directions, or any front-facing dormers will need a full planning application. We assess this at the outset and advise you clearly on what's needed before any work begins.

A typical rear dormer conversion with us takes around eight to ten weeks from the start of structural work to completion. That includes the structural frame, roofing, windows, insulation, boarding, first and second fix joinery, plumbing for the en-suite, NICEIC-certified electrics, and plastering. Materials are sourced through D.J. Redman, our trade merchant partner based in Worthing, which keeps quality high and costs competitive. The result is a properly finished, building-regulation-approved room that adds real value to your home.