Loft conversions in Hove: adding a room over the outrigger

3 November 2026 · Blog

Roof structure exposed during works at Thornhill Close, Hove.

Many Victorian and Edwardian houses in Hove and Brighton have an outrigger: the narrower two-storey wing at the back that usually holds the kitchen and a bathroom or small bedroom above. When you convert the loft, the outrigger roof is a chance to add a second room, or a bathroom, alongside the main dormer.

What’s involved
A typical scheme has a rear dormer on the main roof and a second dormer, or a raised roof, over the outrigger, often linked by a short step or corridor. At Poynter Road in Hove, for example, we provided the structural calculations for a loft conversion with a rear dormer and a second room above the existing outrigger.

The structural questions
• New floor: the existing ceiling joists aren’t designed to be a floor, so new joists are needed, usually supported on steel beams between the party walls.
• The outrigger walls: they were built to carry a light roof, not an extra room. We check their thickness, condition and foundations, and what they can safely take.
• Where the two roofs meet: the junction between the main roof and the outrigger roof needs careful support, often with steel or timber beams and posts.
• Party walls: new beams commonly bear on the party wall, so you’ll usually need a party wall agreement with your neighbour.
• Chimneys: chimney breasts in the loft often need removing or supporting to make the layout work.

Planning and Building Control
Many loft conversions fall within permitted development, but rules on volume, materials and how close dormers come to the edges of the roof apply, and houses in conservation areas, of which Brighton & Hove has many, often need planning permission. Building Control approval is always needed, and it covers the structure, fire safety, stairs and insulation.

What we provide
• Site visit to check the existing roof, walls and floors
• Structural calculations and drawings for Building Control
• Beam, joist and connection details for your builder
• Answers to Building Control’s questions during the build

Our typical fee for dormer loft conversion calculations is £900 – £1,400 inc. VAT.

Common questions

Will I lose ceiling height in the rooms below?
Usually not. The new floor is built just above the existing ceiling, although the height of the new loft rooms depends on the existing roof.

Do I need steel beams?
Most dormer conversions do, to support the new floor and the dormer. The size depends on the spans and loads.

Can the outrigger take a room on top?
Often, yes, but it depends on the walls and foundations. We check them at the visit, and design any strengthening needed.

Our loft work in Brighton & Hove
Poynter Road and Old Shoreham Road in Hove, among others.

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