GS Renovation converts lofts across the London Borough of Barnet, from the interwar semis of N3, N12 and NW4 to the larger suburban houses out towards Mill Hill in NW7. Hipped roofs dominate here, and hip to gable with a rear dormer behind it is the conversion that suits them. We coordinate the engineer and manage Barnet Council building control.
Hip to gable conversions on Barnet's interwar semis
A 1930s semi loses most of its loft volume to the sloping hip at the side, which cuts the usable floor area down to a strip along the ridge. Building that hip up into a vertical gable wall, finished in matching brick or tile hanging, gives you a full length ridge and proper head height across the width of the house. A rear dormer added behind it then squares off the back, and the two together will normally yield a double bedroom, an en suite and a landing that meets the stair regulations.
Indicative London ranges for 2026 put hip to gable plus rear dormer at roughly £55,000 to £80,000, with an en suite adding around £8,000 to £15,000. Interwar Barnet houses usually carry an old cold water tank in the loft, so an early enabling step is removing it and moving the house to a combi boiler or an unvented cylinder. The generous plots around Hadley Common and Mill Hill also mean there is normally somewhere sensible to stand a skip and store materials.
Permitted development, Article 4 and Barnet Council
Semi-detached and detached houses are commonly cited as having a 50 cubic metre volume allowance under permitted development, against 40 for a terrace, which is why hip to gable so often fits without a planning application. The conditions still bite: no extension forward of the roof plane, matching materials, no balconies, and obscure glazing to side windows. Hampstead Garden Suburb in NW11 is a conservation area with tight controls where those rights are heavily restricted, and other parts of the borough carry their own designations, so we establish the position with Barnet Council first.
Because a semi shares a party wall, and the new steel beams that carry the loft floor and the dormer will bear into it, the work is almost always notifiable under the Party Wall etc. Act 1996. The duty to serve notice sits with you as the building owner, not with us as contractor, so we prepare the information your surveyor and your neighbour need and you serve it. Barnet building control then inspects the steel bearings, the fire separation and the stair as the job progresses.
- 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
- Velux and conservation rooflights fitted and flashed
- Building control inspections booked at floor, steel and completion
Why Barnet Homeowners Choose GS Renovation
Barnet homeowners choose GS Renovation because a hip to gable is structural work first and a bedroom second. We bring in the structural engineer, install the steel to their design, prepare your party wall notices, and take Barnet Council building control through to a completion certificate. Fully insured, one dedicated project manager, free no-obligation quotations, and 30+ years of hands-on experience behind the founder.
- Honest answer at survey if your roof will not take a conversion
- Our own trades on site rather than a chain of subcontractors
- Honest updates if a date or a detail has to move
- One point of contact on the phone, not a call centre
- Ridge height measured before any design work is commissioned
- Site left safe and secure at the end of every day