GS Renovation builds loft conversions in Stanmore, on the substantial detached and semi-detached houses spreading out from Stanmore Common. Wide plots, generous roofs and the larger permitted development allowance make this straightforward territory. We coordinate the structural engineer, build the roof structure and take Harrow Council building control to sign-off.
Big roofs, and the room to use them in HA7
Stanmore's interwar and post-war houses were built with depth as well as width, so the roof void is often large enough for two rooms and a bathroom rather than a single bedroom. On a semi or an end house with a hipped flank, building that hip up into a gable adds standing height across the whole width, and a rear dormer then supplies the flat ceiling. Detached houses can sometimes take a dormer on more than one slope, depending on how the roof reads from the street.
Ridge height is rarely the issue on these houses; the position of the new stair usually is. Part K sets the rise, going and headroom, and the stair has to land somewhere that does not ruin a first floor bedroom, which is worth resolving on paper before the roof is opened. Indicative London ranges for 2026 put hip to gable with a rear dormer at roughly £55,000 to £80,000, with an en suite adding roughly £8,000 to £15,000 on top of that.
Harrow Council and the compliance side
Semi-detached and detached houses carry the larger commonly cited allowance of 50 cubic metres of added volume, and many Stanmore lofts sit inside it, provided nothing extends forward of the existing roof plane, materials match, no balcony is formed and side-facing windows are obscure glazed. Permitted development is withdrawn on listed buildings, inside conservation areas and under any Article 4 direction, and Harrow Council confirms which of those apply at your address.
Building control is a separate approval and is required either way. Harrow inspects the fire strategy under Part B, which on a new third storey normally means a protected stairwell to a final exit with fire doors and interlinked alarms, the new floor on engineer-sized joists carried by steel on padstones, the stair, and insulation and ventilation. On a semi, forming a gable off the shared wall is notifiable under the Party Wall etc. Act 1996, with the notice served by you.
- Velux and conservation rooflights fitted and flashed
- Ventilation paths kept clear at eaves and ridge
- Mansard conversions where planning will not accept a dormer
- Insulation between and over rafters to Part L
- Interlinked mains-powered smoke alarms
Why Stanmore Homeowners Choose GS Renovation
Stanmore homeowners choose GS Renovation because a large HA7 roof deserves proper structural planning rather than a standard kit of parts. We coordinate the engineer, build the gable, the steel and the dormer, position the stair sensibly and run Harrow Council building control. Founder Abdelaaziz Saaid has 30+ years of hands-on experience on London roofs, and we are fully insured.
- Paperwork and certificates handed over for when you sell
- Protected stair route and fire doors detailed to Part B
- Free follow-up visit after completion if anything needs attention
- Party Wall notices prepared for steels bearing into a shared wall
- Honest answer at survey if your roof will not take a conversion
- Building control applications and inspections coordinated for you