Loft conversions, house extensions, renovations, basements and new builds across London and Hertfordshire.
Services
Loft conversions, house extensions, renovations, basements and new builds across London and Hertfordshire.
Services
Loft conversions, house extensions, renovations, basements and new builds across London and Hertfordshire.
Services
Loft conversions, house extensions, renovations, basements and new builds across London and Hertfordshire.
Services
Call 020 8037 7332 or get an instant estimate online.
Hip to gable loft cost · London & Hertfordshire
Hip to gable loft conversion cost in London 2026: £60,000 – £114,000 inc. VAT (£50,000 – £95,000 + VAT), and what decides it
By Anderson & the LCCL Construction Team
Finchley N3 · Design & build, LABC award winners 2024 and 2026
A hip-to-gable loft conversion in London costs £60,000 – £114,000 inc. VAT (£50,000 – £95,000 + VAT) in 2026, design and build inclusive — the standard answer for a 1930s semi, usually with a rear dormer and usually permitted development. This page gives you the range by configuration, what is in the figure, what moves it, and how to get an itemised estimate for your roof. On most semis it is a [fixed-price permitted development project](/permitted-development-projects): no planning application, Lawful Development Certificate included, economy specification. The [hip-to-gable permitted development guide](/post/hip-to-gable-loft-conversion-permitted-development) covers the 50 m³ rule; [Bohun Grove EN4](/projects/bohun-grove-en4), our LABC Building Excellence Award 2024 winner, is a hip-to-gable with rear dormer and rear extension in one programme.
Quick answer
£60,000 – £114,000 inc. VAT (£50,000 – £95,000 + VAT) for a hip-to-gable loft conversion, usually with a rear dormer, design and build inclusive. Postcode dependent.
Usually permitted development on a semi within 50 m³; we obtain a Lawful Development Certificate. Conservation and Article 4 areas need a planning application.
10–12 weeks on site; 8–12 weeks of design and approvals before that.
A free 30-minute phone call with our team, no obligation.
Guide price
£60,000 – £114,000 inc. VAT (£50,000 – £95,000 + VAT)
Typical build
10–12 weeks on site
Guarantee
12-month workmanship guarantee; 10-year LABC structural warranty
Awards
LABC 2024 & 2026 winners
LABC Building Excellence Award 2024
Best Residential Extension in London — Bohun Grove, East Barnet EN4: rear extension, hip-to-gable loft conversion and whole-house renovation
LABC Building Excellence Awards 2026
London Regional Winner, Best Conversion or Alteration — Weech Road, Hampstead NW6: penthouse loft conversion and full renovation
One contract
Architecture, structural engineering, planning, construction and project management — all under one contract
Guaranteed & insured
12-month workmanship guarantee; 10-year LABC structural warranty
How much does a hip to gable loft conversion cost in London in 2026?
Guide ranges by size, design and build inclusive. Every project is priced from your postcode and house type.
Conversion
Typical use
Guide range
Hip-to-gable only
Gable end rebuilt, Velux windows, one large bedroom
£60,000 – £74,400 inc. VAT (£50,000 – £62,000 + VAT)
Hip-to-gable + rear dormer
Master bedroom with en-suite and a full-height rear wall — the standard semi conversion
£72,000 – £96,000 inc. VAT (£60,000 – £80,000 + VAT)
Double hip-to-gable + dormer (detached)
Both hips rebuilt, two bedrooms and a bathroom
£90,000 – £114,000 inc. VAT (£75,000 – £95,000 + VAT)
Related conversion
Guide range
On site
Rear dormer only
Keeps the hip; smaller room, lower cost
£56,400 – £80,400 inc. VAT (£47,000 – £67,000 + VAT)
8–10 wks
Mansard
New roof across the whole footprint — the most space, usually planning
£76,800 – £148,800 inc. VAT (£64,000 – £124,000 + VAT)
12–16 wks
Loft + rear extension together
The Bohun Grove EN4 combination under one programme
See loft + extension
One programme
Where the money goes
What a design and build price is made of, and which lines are priced separately.
Cost element
What it covers
How it is priced
Survey, design and approvals
Measured survey of the roof, drawings, lawful development certificate or planning, building-regulations drawings, structural calculations
Included in the design and build price; council fees at cost
Structure
New floor joists and steels, dormer or gable structure, roof and windows
The largest share — a dormer adds a box structure, a hip-to-gable rebuilds a roof slope, a mansard replaces the roof
Stairs, fire and insulation
New staircase, fire doors, escape windows, insulation to building regulations
Included; the staircase position is the single biggest design decision
First and second fix
Electrics, plumbing, plaster, decoration
Included
Bathroom or en-suite
Where specified
Included to a sanitaryware allowance; items above the allowance are supplied by you or through us
Party wall
Notices to each adjoining owner where the new steels bear on the shared wall
£300 per notice at cost; surveyor from £750 if a neighbour dissents
Location
Access, parking, conservation conditions
Varies by postcode — the instant estimate applies your area
Added afterwards
—
Nothing: the figure on your itemised estimate is the figure you pay
What the price includes: survey, drawings, lawful development certificate or planning, building-regulations drawings, structural calculations, new floor structure, dormer or gable structure, roof and windows, stairs, insulation, fire doors and escape windows, first and second fix, plastering, decoration, a bathroom where specified, LABC certificate and guarantees. Not included unless specified: sanitaryware above the allowance, bespoke joinery, party wall surveyor fees if a neighbour dissents (from £750). The figure on your itemised estimate is the figure you pay — nothing is added afterwards. Postcode dependent — the instant estimator adjusts the range for your area in thirty seconds, and a detailed itemised estimate follows one survey. Already have an architect's drawings and calculations? We price and build from them as drawn.
What moves the price: whether the rear dormer is included (it nearly always should be); the gable wall — blockwork rendered or brick to match the house; the steels, which are longer on a semi because the new floor spans to the new gable; the bathroom; the staircase position; and whether the front slope is re-tiled to match the new gable. Inner and Central London (Camden, Islington, Hackney, Wandsworth, Hammersmith, Westminster, Kensington & Chelsea, the City) cost more than outer London and Hertfordshire a little less — the instant estimate applies your postcode. These are estimated ranges — every home is surveyed and costed individually.
What the price includes
Design and build inclusive — one contract from the first sketch to the completion certificate.
Measured survey of the roof space, stairs and existing structure
Architectural design and drawings, with revisions until you're happy
Lawful Development Certificate or planning application, prepared and submitted for you
Building regulations drawings and structural calculations by our chartered engineer
Party wall notices served on your behalf (£300 each, at cost)
New floor structure, steels, dormer or gable structure, roof and windows
Staircase, insulation, fire doors and escape windows to building regulations
Plaster finish, first-fix electrics and plumbing; bathroom or en-suite where specified
Second-fix carpentry, decoration and the items you supply fitted
LABC inspections and completion certificate
A dedicated project manager and a weekly progress update
12-month workmanship guarantee; 10-year LABC structural warranty
Recent hip to gable projects
Bohun Grove, East Barnet EN4 — rear extension, hip-to-gable loft and whole-house renovation
LABC 2024 Best Residential Extension in London
Semi-detached family home One programme loft + extension + renovation
A total renovation of a family semi: a rear extension opening into a full-width kitchen and dining space with floor-to-ceiling glazing and skylights, a hip-to-gable loft conversion with a rear dormer, two Lusso Stone bathrooms, enlarged bedrooms, new windows throughout, a regulated outbuilding and landscaping.
Because the loft and extension ran under one contract, the steelwork for the open-plan ground floor and the loft floor was designed together and lifted in on the same day — one crane hire, one scaffold, one building-control file.
See the Bohun Grove project · All projects
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ANDERSON · FOUNDER, LCCL CONSTRUCTION
Anderson's advice: talk to next door before the scaffold goes up
Semi-detached hip-to-gable and rear dormer combinations almost always fall under permitted development, but neighbours often object informally — to the council, to the building inspector, to you. Talk to them before the scaffold goes up. We will show them the drawings with you.
It costs nothing, and it is the difference between a quiet twelve weeks and a formal complaint that stalls the job.
“LCCL Construction was the right company to help with my loft conversion. I heard of other people's challenging experiences with building works so I was very careful which company I chose. LCCL Constructions was professional, trustworthy and worked to the…”
KashImaging · Trustpilot
“Contracted lccl construction to design and build hip to gable loft conversion, after much research I found Lccl construction to be the most efficient and reliable company to deal with, the initial design phases started immediately their architects attended…”
Behar · Trustpilot
“2ND project with LCCL construction wraparound house extension. Completed full design and build process to our home in Finchley north London. Previously they have design and build our loft conversion 4 years on and still it is in excellent condition.…”
Anthony · Trustpilot
Cost questions we get asked most
Because a whole roof slope is rebuilt as a vertical gable wall, with longer steels spanning to it, before the dormer goes on. It costs £60,000 – £114,000 inc. VAT (£50,000 – £95,000 + VAT) against £56,400 – £80,400 inc. VAT (£47,000 – £67,000 + VAT) for a rear dormer alone — and it gives the biggest room a semi can have under permitted development.
Nearly always. The hip-to-gable makes the loft wide; the rear dormer makes it tall at the back, which is where the bedroom and en-suite go. Hip-to-gable alone (£60,000 – £74,400 inc. VAT (£50,000 – £62,000 + VAT)) suits a house that only needs one large room with Velux windows.
Sanitaryware above the allowance, bespoke joinery, council fees, and party wall surveyor fees if a neighbour dissents (from £750). Survey, design, approvals, structure, stairs, insulation, fire safety, first and second fix, decoration, LABC sign-off and guarantees are in the price.
Usually not on a semi: within 50 m³ it is permitted development and we obtain a Lawful Development Certificate. Conservation areas, Article 4 areas and a gable facing the street on a corner plot need a planning application.
Yes — every figure is postcode dependent. Parking, access, conservation-area conditions, party wall complexity and logistics all move it, so the instant estimator adjusts the range for your postcode and the detailed itemised estimate follows one survey.
No. The figure on your itemised estimate is the figure you pay — nothing is added afterwards. Items you choose, such as kitchen units or sanitaryware above the allowance, are listed separately before you sign.
Two steps. The instant estimator gives you a range for your postcode and project in thirty seconds. Then one measured survey gives you a detailed itemised estimate — design, planning, structure, construction and warranty priced line by line — with no obligation.
A 12-month workmanship guarantee on every project, with a 10-year LABC structural warranty. Building control sign-off is through LABC — we are an LABC Registered Partner and LABC Building Excellence Award winners in 2024 and 2026.
Where we build
From Finchley N3 we cover North London, North-West London, Central London, South-West and West London, and Hertfordshire — and we also work across the rest of London, Buckinghamshire, Surrey, Kent and Essex. Recent lofts: Hampstead NW6, East Barnet EN4, Putney SW15, Wood Green N22, Borehamwood WD6, Hendon NW4 and Marylebone W1.