A loft conversion is the single best investment
you can make in a London home.
You already own the space — it's just above your ceiling. A loft conversion turns a cold, dusty void into a fully habitable room with proper head height, natural light, heating, electrics and plumbing. It adds a bedroom, a bathroom, a study, or all three — without losing any garden space, without extending the footprint, and often without needing planning permission.
In North West London, a well-executed loft conversion typically adds £100,000–£250,000 to the property value. For a build cost of £45,000–£90,000, that's a return most investments can't touch.
We've converted lofts in Victorian terraces, Edwardian semis, 1930s houses and mansion flats across NW3, NW6, NW1 and NW8. We know which streets have the head height, which roof types suit which conversion, and what Camden's planners will and won't approve.
Four ways to convert your loft
The right type depends on your roof structure, head height, planning constraints and budget. Here's how they compare.
Rear Dormer Loft Conversion
A box-shaped dormer built out from the rear roof slope, creating a flat-ceilinged room with full standing height across most of the floor area. The front roof slope stays untouched. This is the workhorse of London loft conversions — it maximises usable space, and on most properties it can be built under permitted development.
Mansard Loft Conversion
The rear roof slope is rebuilt at a near-vertical angle (72°), with a small flat roof section at the top. This creates the most internal space of any conversion type and is the standard approach in conservation areas where dormers may not be permitted. Mansards always require planning permission due to the change in roof form.
Hip-to-Gable Conversion
If your house has a hipped (sloped) side roof, we can extend the party wall upward and rebuild the hip as a flat gable — effectively squaring off the loft. Often combined with a rear dormer for maximum space. Ideal for 1930s semis and end-of-terrace properties. Usually permitted development.
L-Shaped Dormer Conversion
Two dormers — one on the main rear roof and one on the rear outrigger (the section that projects at the back of Victorian terraces). The result is an L-shaped floor plan with space for a large bedroom, en-suite bathroom, walk-in wardrobe and a separate study area. The most spacious conversion for Victorian terraces.
What actually happens on site
Most loft conversions take 8–12 weeks. Here's the journey from scaffolding going up to the final clean.
Scaffold, Strip & Steel
Scaffolding erected around the rear of the property. Existing roof tiles and felt stripped on the rear slope. Structural steelwork installed — ridge beam, purlins and any hip-to-gable steels. New floor joists laid and anchored. This is the noisiest phase.
Dormer Construction & Weathertight
Dormer frame built in timber, faced with cladding (GRP, zinc, lead or tile-hanging depending on planning requirements). Flat roof built with warm-deck EPDM. Rear windows and any Juliet balconies fitted. The loft is now watertight — the rest of the work happens inside.
Staircase & Fire Compliance
The new staircase is built — typically positioned over the existing stairs to minimise loss of second-floor space. Fire doors, smoke detectors and emergency lighting installed as required by Building Regulations Part B. This is non-negotiable for a habitable loft.
First Fix: Electrics, Plumbing & Insulation
Electrical wiring for power, lighting and any media points. Hot and cold water supply and waste connections for the en-suite. Insulation — typically 100mm Celotex between rafters plus additional layers to meet Part L thermal requirements. Plasterboard to walls and ceilings.
Second Fix, En-Suite & Decoration
En-suite bathroom tiled, sanitaryware and shower fitted. Sockets, switches and lights installed. Flooring laid. Walls and woodwork decorated. Bespoke eaves storage built if specified. Radiators or underfloor heating connected.
Scaffold Down, Clean & Handover
Building Control final inspection. Scaffold dismantled. Professional deep clean. You receive your completion certificate, electrical certificate, gas certificate (if applicable), and our 5-year workmanship warranty.
What you get as standard
No hidden extras. Every loft conversion includes these as part of our fixed-price contract.
Structural Engineering
Chartered engineer's calculations and drawings for all steelwork, floor joists and load paths. Submitted to Building Control on your behalf.
Building Control
Full Building Regulations application, all on-site inspections managed, and completion certificate issued at handover.
Party Wall
Party Wall notices served where required. We arrange the surveyor and manage the process with your neighbours.
Staircase
Purpose-built timber staircase to Building Regulations, positioned to minimise loss of space on the floor below. Balustrade and handrail included.
En-Suite Bathroom
Fully plumbed and tiled en-suite with shower, WC, basin, heated towel rail and extractor fan. You choose the sanitaryware and tiles.
Fire Compliance
FD30 fire doors to all habitable rooms on the escape route, interlinked smoke/heat detectors, and emergency lighting. Non-negotiable for Building Regs.
Insulation
Full thermal insulation to current Part L standards. High-performance Celotex or equivalent between and below rafters. U-values certified.
Electrics & Lighting
Full electrical installation with spotlights, power sockets, USB points, and media plates. NICEIC-certified electrician. Certificate at handover.
Decoration
All walls and ceilings emulsion painted (2 coats), all woodwork satin-finished. You choose the colours. Ready to move furniture in.
"Ross and team completely transformed our loft into a stunning master suite with en-suite and walk-in wardrobe. The attention to detail was exceptional — from the bespoke eaves storage to the Juliet balcony. Finished on time and exactly on budget."Cirus RehmanHomeowner, Hampstead NW3
Loft conversions we've designed and built
Victorian Terrace, Belsize Park NW3
Full mansard loft conversion in a conservation area. Master bedroom with en-suite shower room, bespoke eaves wardrobes, and Velux roof windows to the front. Planning application approved with slate-clad mansard and lead-rolled flat roof. Party wall agreement with both neighbours managed in-house.
2 Holland Avenue, Wimbledon SW19
Rear dormer loft conversion delivered as part of a larger extension programme — loft, two-storey rear and single-storey side extension. The loft provides a master bedroom with en-suite and dedicated study area, with stairs positioned to maintain the existing bedroom layout below.
Edwardian Semi, Camden NW1
L-shaped dormer across the main roof and rear outrigger. Created a 40 sqm master suite with walk-in wardrobe, luxury en-suite with freestanding bath, and a separate home office in the outrigger section. Bespoke staircase with glass balustrade. All under permitted development — no planning application needed.
What does a loft conversion cost?
Realistic ranges for North West London. We provide a fixed price after surveying your loft — these are guides based on recent projects.
| Loft Conversion Type | Typical Range |
|---|---|
| Rear dormer (standard spec) | £45,000 – £60,000 |
| Rear dormer (premium spec) | £60,000 – £80,000 |
| Mansard conversion | £55,000 – £85,000 |
| Hip-to-gable + rear dormer | £50,000 – £75,000 |
| L-shaped dormer | £60,000 – £90,000 |
| Velux / rooflight only (no dormer) | £30,000 – £45,000 |
| En-suite bathroom (within loft) | Included in price |
| Bespoke eaves storage | £1,500 – £4,000 |
| Juliet balcony | £800 – £2,000 |
All prices exclude VAT. Includes structural steelwork, staircase, fire compliance, electrics, plumbing, insulation, plastering, decoration and Building Control sign-off.
"A company where you get value for your money while at the same time achieving excellent quality. Their work is carried out on time and within budget. We've worked with them on multiple projects and they never disappoint."Brian Ingham, DirectorGreen Evolution Limited
Loft conversion FAQ
Most lofts can. The key requirement is head height — you need at least 2.2m from the top of the existing ceiling joists to the underside of the ridge beam. If you don't have that, a mansard or hip-to-gable conversion can create additional height. We'll measure during the free site visit and tell you exactly what's possible.
Most rear dormer and hip-to-gable conversions fall under Permitted Development and don't need a planning application. Mansards always need planning permission because they change the roof form. Properties in conservation areas may have restricted PD rights. We handle all of this — if you need planning, we prepare and submit the application.
A standard rear dormer takes 8–10 weeks on site. A mansard or L-shaped conversion takes 10–14 weeks. Add 4–8 weeks beforehand for design, engineering and party wall agreements. We give you a firm programme before work starts.
Yes — almost all our clients stay in the house throughout. The work is concentrated in the loft and roof, so the rest of the house remains liveable. The noisiest period is the first 2 weeks (scaffolding, roof strip, steelwork). The staircase installation temporarily affects the floor below for about 3–4 days.
Not usually. The most common approach is to position the new staircase above the existing stairwell, taking space from the landing or a corner of a second-floor bedroom. We design the staircase layout during the feasibility stage so you can see exactly what you'll lose before committing.
When you add a habitable room at loft level, Building Regulations (Part B) require a protected escape route — FD30 fire doors to all habitable rooms on the escape route, interlinked smoke and heat detectors on every level, and emergency lighting. This is mandatory and non-negotiable. We include it as standard.
In North West London, a loft conversion with en-suite typically adds £100,000–£250,000 to the property value — depending on the area, property type and quality of finish. Even at the lower end, that's a significant return on a build cost of £45,000–£90,000.
Find your local loft conversion page
Book a free loft survey
We'll measure your loft, check the head height and roof structure, assess permitted development eligibility, and give you a realistic price and timeline — completely free, no obligation.
Unit 3, Palace Court, 250 Finchley Road, Hampstead, London NW3 6DN
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