GS Renovation converts lofts in New Cross, where SE14 is dominated by Victorian terraced housing, much of it retaining a rear closet wing. That plan makes the L-shaped dormer the standard answer, and we handle the engineer's steel, the fire strategy, the party wall notices and Lewisham building control as one package.
The SE14 terrace and the L-shaped dormer
A New Cross terrace typically runs bay front, main roof back to the rear wall, then a lower closet wing along one side of the rear elevation. An L-shaped dormer follows that shape, giving a double bedroom with full standing height and a shower room in the wing. Indicative London ranges for 2026 put it at roughly £55,000 to £80,000, with an en suite fit-out inside that figure rather than added on top of it.
Where the closet wing has already been swallowed by a ground floor extension, or was never there, a straight rear dormer at roughly £45,000 to £65,000 is the alternative. Either way the ridge is measured first: around 2.2m to 2.4m of existing height is what makes a conversion viable without dropping the ceilings below. Victorian roofs in SE14 are purlin framed, so the structure can generally be reworked around a new floor.
Lewisham Council, Telegraph Hill and the regulations
Outside conservation areas, a rear dormer on a terrace can sit within the 40 cubic metre permitted development allowance if it stays behind the roof plane, matches materials and has obscure glazed side windows. The Telegraph Hill conservation area and other designated parts of the borough remove that allowance, so a full application to Lewisham Council is needed. We check the designation on your address before any drawings are commissioned.
Building control is unavoidable in both cases. Taking a two storey house to three triggers Part B, so the stair becomes a protected route to a final exit with fire doors to the rooms off it and interlinked alarms on every floor. The new floor is carried on engineer-designed steels bearing on padstones in the party walls, sitting clear of the old ceiling joists, and the water tank comes out as an enabling step.
- Hip to gable conversions on semi-detached and end terrace roofs
- Protected stair enclosure and fire doors to Part B
- En suite plumbing, drainage and mechanical extraction
- New floor joists independent of the existing ceiling
- Ventilation paths kept clear at eaves and ridge
Why Choose GS Renovation in New Cross
New Cross terraces are a house type GS Renovation knows well, and one team covers the whole job: engineer, steelwork, dormer, stair, fire strategy, party wall notices and Lewisham building control through to a completion certificate. Fully insured, building control compliant, free no-obligation quotations, and 30+ years of hands-on experience behind the founder.
- Photographs kept at each stage for your records
- Roof made good, leadwork and guttering finished properly
- Protected stair route and fire doors detailed to Part B
- Building control applications and inspections coordinated for you
- Materials priced at options, so you choose the finish
- Honest answer at survey if your roof will not take a conversion