GS Renovation converts lofts across Coulsdon, where 1930s semi-detached and interwar houses on generous plots sit on the hills south of Purley. In CR5 the classic scheme is hip to gable plus a rear dormer, which turns a cramped hipped roof into two usable rooms. We build to the engineer's design and Croydon Council building control.
Hip to gable conversions on Coulsdon semis
The hipped roof that gives a 1930s Coulsdon semi its shape is also what wastes the space inside it, because the sloping side cuts the usable floor away exactly where you want to stand. Building that hip up to a vertical gable end recovers the full width, and a rear dormer behind it then gives standing height across the back. Together they routinely produce a double bedroom, an en suite and a landing where there was previously only a hatch and a few boards.
Interwar semis in CR5 tend to have decent ridge height, so the 2.2m to 2.4m minimum is usually met, but the roof structure is often a cut roof with purlins that the new gable has to pick up. Your structural engineer sizes the steels that span between the party wall and the new gable, we install them on padstones, and the new floor joists sit on those steels rather than on the existing ceiling joists, which were never designed for a floor load.
Stairs, regulations and cost in CR5
The generous plots in Coulsdon do not solve the stair problem, which is the same everywhere: Part K sets the rise, going and headroom, and the new flight usually eats into a bedroom or the landing. A space-saver stair with alternating treads is permitted only where it serves a single room, so it rarely works for a proper loft bedroom and en suite. Part B then requires the whole stair to be a protected route to a final exit, with fire doors and interlinked alarms.
Semi-detached houses get a 50 cubic metre permitted development allowance rather than the 40 that terraces get, with the usual conditions on matching materials, no projection forward of the roof plane and obscure glazing to side windows. That does not make it automatic, and Croydon Council conservation areas and Article 4 directions override it, so we check first. On indicative London ranges for 2026, hip to gable with a rear dormer sits at roughly £55,000 to £80,000.
- Trussed roofs redesigned before any web is cut
- Hip to gable conversions on semi-detached and end terrace roofs
- L-shaped dormers over a rear closet wing
- Interlinked mains-powered smoke alarms
- Velux and conservation rooflights fitted and flashed
Why Coulsdon Homeowners Choose GS Renovation
Coulsdon families choose GS Renovation because a hip to gable is heavier structural work than it looks, and we do that kind of work every week. We coordinate the engineer, form the gable and set the steels correctly, handle party wall detail for the shared wall, and take Croydon building control through to certificate. Rated 4.9 from 31 MyBuilder reviews.
- Dust screens and floor protection in occupied homes
- Neighbours given notice before the noisy stages
- Water tank removed and the system converted where it blocks the space
- Protected stair route and fire doors detailed to Part B
- Roof type assessed so you get the scheme your house can actually take
- A dedicated project manager from first survey to handover