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RIBA CHARTERED PRACTICE · WORTHING, WEST SUSSEX

Loft conversions

For a lot of houses on the Sussex coast, the extra bedroom is already there — under the roof, full of boxes. A loft conversion turns it into rooms you actually use: bedrooms, a bathroom, a study, without giving up any of the garden. 

What kind of loft

  • Rooflight conversion The roof stays the shape it is, with windows set into the slope. The simplest route, where there is already enough height.
  • Rear dormer The back slope of the roof is built out to give full standing height across most of the floor. The most common way to fit in a bedroom and a bathroom.
  • Hip-to-gable with a rear dormer On a house with a sloping, hipped side roof, the side is squared off into a gable first. That is what makes room for a staircase and a usable floor on many semi-detached and detached houses.

Planning

Many loft conversions on houses can be built under permitted development, without a planning application, within set limits. The roof space can grow by no more than 40 cubic metres on a terraced house (end of terrace included), or 50 cubic metres on a semi-detached or detached house, and any earlier roof extension counts towards that. Nothing can rise above the highest part of the existing roof, nothing can be built out on the front roof slope facing the road, and balconies and roof terraces are not allowed. The materials have to look like the existing house, and any window in a side wall or side roof slope has to be obscure-glazed and fixed shut below 1.7 metres. Flats, maisonettes, houses in a conservation area and houses where permitted development rights have been removed need planning permission for any loft enlargement. Where a loft is permitted development, we usually recommend a Lawful Development Certificate from the council, so you have it in writing when you come to sell. We establish which route applies before we quote, because it changes the work. 

Building Regulations

Every loft conversion needs Building Regulations approval, whether or not it needs planning. A new floor in the roof affects the whole house: the new staircase, a safe way out in a fire, which on most houses means protecting the staircase all the way down, insulation, and the structure, which is designed by a structural engineer. We prepare the Building Regulations drawings, coordinate the engineer’s information into them and make the Building Control submission. On a semi-detached or terraced house the work usually involves the party wall, so your neighbours may need formal notice. 

Recent work

What Wouldn't Fit, Fit

A two-bedroom bungalow, remade as a family house, Lancing 

Completed 2026 · Planning permission + Building Regulations

The family had outgrown a two-bedroom bungalow, but not the street. The hipped side of the roof was turned into a gable and a dormer built across the back, with a Juliet balcony, giving three bedrooms, an en-suite and a bathroom upstairs. Downstairs, the separate living room, dining room and kitchen became one room across the back of the house, opening onto the garden through wide folding doors, with a small single-storey extension at the side. Planning permission was granted once the small front dormer had been moved to sit centrally above the window below it. 

Looking across the kitchen island and dining table to wide folding doors onto the garden
The new kitchen and dining room across the back of the house, with a green island and built-in bench seat.
The rear of the remade bungalow, with a dark-clad dormer and Juliet balcony above wide folding doors to the garden.
Before

Testimonial

She listened to my ideas and made what I thought wouldn't fit, fit. Made our dream house a reality.
Joanna, Google review
Rated 5 out of 5

The Only Way Was Up

Two bedrooms and a shower room under the roof, Worthing 

Completed early 2026 · Permitted development + Building Regulations 

The family needed more bedrooms and a second bathroom. The back of the house had already been extended, so the only way left was up. The hipped side roof was squared off into a gable and a dormer built across the back, giving a full-height bedroom and a shower room overlooking the garden. A second bedroom at the front sits under the slope, lit by rooflights. A new staircase continues up from the first-floor landing.

The rear of a semi-detached house with a new dormer clad in dark tiles across the roof.
The loft shower room, with yellow metro tiles, a walk-in shower and a window to the rear
A loft bedroom under the roof slope, with two large rooflights and herringbone floor
Before

Frequently Asked Questions

Often not — see Planning above. We confirm it for your house before any design work starts.

Usually yes. Most of the work happens in the roof, and the new staircase is connected at the end.

The new staircase has to come from somewhere, usually the landing or a small bedroom. Working out where it goes is the first design question. 

Is there a room's worth of space
above your head?

Most people arrive with a question that sounds simple and is not: can we do this, will we get permission, and what will it cost to build?
A Feasibility & Options Study answers all three, in writing, in about three weeks.

£625 + VAT (£750 total payable)
Credited in full against your design fee if you appoint us within six months. 

What the study includes
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