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.
New build houses · London & Hertfordshire
New build construction London and Hertfordshire: cost per square metre, planning and timeline
By Anderson & the LCCL Construction Team
Finchley N3 · Design & build, LABC award winners 2024 and 2026
Building a new house — on a plot, in a garden, or replacing an existing house — is the one project where design, engineering, planning and construction have to be a single programme from the first day. LCCL designs and builds new homes under one contract: our 3,033 sq ft house at Lancaster Avenue, Hadley Wood EN4 is the reference. This page gives you the 2026 numbers per square metre, what a new build needs that an extension does not (full planning, CIL, a warranty, services), and a realistic 9–14 month programme.
Quick answer
£2,200 – £4,500 per m² (zero-rated for VAT) of finished floor area, from £250,000 (zero-rated for VAT) for a complete house, design and build inclusive. Plot, finance and professional fees on top. Postcode and specification dependent.
Always a full planning application — there is no permitted development for a new house. Pre-application advice is usually worth it; CIL is payable in most boroughs.
9–14 months on site; 6–12 months of design, planning and pre-construction before that.
A free 30-minute phone call with our team, no obligation.
Guide price
£2,200 – £4,500 per m² (zero-rated for VAT)
Typical build
9–14 months on site
Guarantee
10-yr structural warranty via LABC
Reference
Lancaster Avenue, Hadley Wood EN4
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
What a new build from LCCL includes
Design and build inclusive — one contract from the first sketch to the completion certificate.
Feasibility review of the plot, planning history and constraints before you commit
Measured and topographical survey; ground investigation where the site needs it
Architectural design to planning, then to construction detail, with revisions until you're happy
Pre-application advice where the borough engages; full planning application, design and access statement
Building-regulations drawings and structural calculations by our chartered engineer
Party wall notices where the new house is near a neighbour's structure (£300 each, at cost)
Demolition of an existing house where applicable; foundations, drainage and utility connections
Superstructure, roof, windows and doors to a weather-tight shell
First and second fix throughout, kitchens, bathrooms, flooring and decoration to the agreed specification
LABC inspections and completion certificate; 10-year structural warranty via LABC
A dedicated project manager and a weekly progress update
Energy performance certificate and the handover pack you need to sell or let
How much does a new build house cost in London and Hertfordshire in 2026?
Guide ranges per square metre of finished floor area, design and build inclusive. Every project is priced from the plot, the drawings and the specification.
Specification
What it means
Guide rate
Standard (£2,200 – £2,900 per m² (zero-rated for VAT))
Good-quality mainstream materials, standard kitchens and bathrooms, gas or heat-pump heating
150 m² house ≈ £330,000 – £435,000 (zero-rated for VAT)
High specification (£2,900 – £3,700 per m² (zero-rated for VAT))
Larger glazing, stone and hardwood finishes, premium kitchens and bathrooms, underfloor heating throughout
200 m² house ≈ £580,000 – £740,000 (zero-rated for VAT)
Luxury (£3,700 – £4,500 per m² (zero-rated for VAT))
Bespoke joinery, structural glazing, basement or pool, full home technology — Lancaster Avenue EN4 territory
280 m² house ≈ £1,035,000 – £1,260,000 (zero-rated for VAT)
Not in the build rate
Guide
Notes
Planning, CIL and building control fees
CIL varies by borough and floor area — often tens of thousands on a London house
We quantify it at feasibility stage
Professional and legal fees outside our contract
Solicitor, valuer, lender's surveyor, warranty provider fees
Varies by lender and site
Demolition and site clearance
Priced per site
Included in our estimate where a house is replaced
What the rate includes: feasibility, surveys, architectural design, planning application, building-regulations drawings, structural calculations, the complete construction from foundations to decoration at the agreed specification, LABC sign-off and a 10-year structural warranty. Not included: the plot, finance, CIL and statutory fees, and professional fees outside our contract. 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.
What moves the rate: ground conditions and foundation type (piled foundations on clay near trees are common in North London and Hertfordshire); the amount of glazing and structural steel; a basement; the specification of kitchens, bathrooms and joinery; site access on a tight London plot; and utility connections, which can take months to arrange with the providers. 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.
New builds by site type
Replacement dwelling
An existing house is demolished and a larger, better-planned one built in its place — the most common new build in Barnet, Enfield and the Hertfordshire towns. Planning judges the new house against the street and the neighbours' amenity; the existing footprint and volume are the starting point for what is acceptable.
Infill or garden plot
A house on a plot carved from a large garden or a gap in the street. Access, parking, daylight to neighbours and the character of the street decide the application; pre-application advice is nearly always worth the fee.
Self-build with your own architect
Where you already have planning drawings, we take the project from technical design through construction under one contract — or provide the structural calculations and project management as separate services.
Planning
Do you need planning permission for a new build?
Always. There is no permitted development for a new house, so the application is designed for from the first sketch.
Stage
What happens
Time
What we do
1. Feasibility
Planning history, constraints, precedent, a first massing
2–4 weeks
We tell you what the plot will realistically take before you buy or commit
2. Pre-application advice
Meeting or written advice from the borough
4–8 weeks
Recommended on almost every new build; we prepare the pack
3. Full planning application
Drawings, design and access statement, surveys as required (trees, ecology, flood, daylight)
8–13 weeks
Application, consultation responses and negotiation with the officer
4. Conditions and CIL
Discharge of pre-commencement conditions; CIL assumption of liability and commencement notice
4–8 weeks
We handle the paperwork — missing the CIL notice forfeits any relief
Building regulations, warranty & party walls
The other approvals a new house needs
A new house needs full building-regulations approval — structure, fire, energy (Part L), ventilation, drainage, accessibility (Part M) and, on a London site, usually a sustainable drainage strategy. We do this through LABC with full-plans drawings and our own structural calculations. A 10-year structural warranty is required by almost every lender and buyer; ours is provided through LABC.
Where the new house is built close to a neighbour's structure or within 3 m of their foundations, the Party Wall Act applies; notices go out at least two months before we start.
The Community Infrastructure Levy is the cost that surprises most self-builders: it is charged per square metre of new floor area at the borough's rate, and the self-build exemption only applies if the forms are submitted before work starts. We quantify it at feasibility stage and run the exemption process for you.
New build planning permission guide · How long a new build takes
Recent new build 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: use pre-application advice where the council is helpful
Wandsworth planning is much more helpful on pre-application advice than Islington in our experience. Where a borough engages, a pre-app meeting before the full application saves a refusal and a resubmission; where it does not, a well-argued design statement and precedent search do more.
We know which boroughs are which because we apply in them every month — and we tell you before you pay a pre-app fee whether it is worth it for your address.
How a new build runs with LCCL
From feasibility to the completion certificate — one team, one contract, one point of contact. Design, planning and pre-construction typically take 6–12 months before work starts on site.
MONTH 0
Free consultation call
A 30-minute phone call about the plot, what you want to build and a realistic budget. If you have not bought the plot yet, we can review it before you do.
MONTHS 1–3
Feasibility, survey & design
Planning history and constraints, topographical survey, ground investigation, concept and planning drawings, and your detailed itemised estimate — design, planning, structure, construction and warranty priced line by line.
MONTHS 3–9
Planning & pre-construction
Pre-application advice, full planning application, conditions, CIL, building-regulations drawings, structural design, utility applications, party wall notices. Nothing starts on site until it is signed off.
BUILD
On site
9–14 months: demolition where needed, foundations, drainage, superstructure, roof, weather-tight shell, first fix, plaster, second fix, kitchens and bathrooms, decoration, external works. Weekly updates from your project manager.
HANDOVER
Sign-off
Snagging, LABC final inspection and completion certificate, 10-year structural warranty, EPC and the handover pack. One point of contact from the first sketch to the keys.
“We are very happy with the services from Lccl, Alex has done a great job on design and construction. We have used Lccl in the past for our rear house extension and have come back to instruct Lccl for our loft conversion too to our house in North London.”
Mia M · Google Reviews
“The Lccl construction team built my extension with a quick and clean service, they worked non stop through the winter weather.. I would highly recommend this company!”
Chris Dunn · Google Reviews
“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
New build questions we get asked most
£2,200 – £4,500 per square metre (zero-rated for VAT) of finished floor area in 2026, design and build inclusive — from about £330,000 for a 150 m² house at a standard specification to over £1,000,000 for a 280 m² luxury house. The plot, finance, CIL and statutory fees are on top. Hertfordshire is a little below outer London and Central London above it — the instant estimate applies your postcode.
Nine to fourteen months on site, plus 6–12 months of feasibility, design, planning and pre-construction before that. Utility connections and pre-commencement planning conditions are the items that most often stretch the pre-construction period, which is why we start them the week planning is granted.
Always — there is no permitted development for a new dwelling. Pre-application advice is worth it on almost every site; the full application takes 8–13 weeks, and pre-commencement conditions must be discharged before work starts.
The Community Infrastructure Levy is a charge per square metre of new floor area at your borough's rate, and it can run to tens of thousands of pounds on a London house. A self-build exemption exists but only if the forms are submitted before work starts and you live in the house for three years. We quantify it at feasibility stage and run the exemption for you.
Yes — a replacement dwelling is the most common new build we do in Barnet, Enfield and Hertfordshire. Planning judges the new house against the street and the neighbours; the existing footprint and volume are the starting point for what is acceptable, and we test it at feasibility before you commit.
Yes — a 10-year structural warranty through LABC, which lenders and buyers require, plus our 12-month workmanship guarantee. Building control sign-off is through LABC throughout.
Yes. If you have planning drawings already, we take the project from technical design through construction under one contract, or provide structural calculations and project management as separate services. Most clients find one contract simpler — one point of contact, one programme, no gap between the drawings and the build.
Per square metre, a new house at a standard specification costs more than an extension but you get a modern, efficient, well-planned house rather than an improved old one — and on a replacement dwelling the value uplift can be substantial. We are not valuers; our guide on new build vs extension covers the trade-offs and a local agent should confirm the numbers.
Where we build new houses
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. New builds are most often in Barnet, Enfield and the Hertfordshire towns — Hadley Wood, Potters Bar, Borehamwood, St Albans, Harpenden and Welwyn Garden City — where plots and replacement dwellings are more common than in Inner London.