LABC Building Excellence Award 2024: Best Residential Extension in London — Bohun Grove, East Barnet EN4
By Anderson & the LCCL Construction Team | Finchley N3
In 2024 LCCL Construction won the LABC Building Excellence Award for Best Residential Extension in London for Bohun Grove, a 1930s semi-detached house in East Barnet EN4 that we designed and rebuilt from the ground floor to the roof. It was our first LABC award, and the project is still the one we show people who ask what a whole-house design & build programme looks like. With our second award now confirmed — Weech Road in Hampstead NW6, London Regional Winner 2026 — this is the story of the first.
The LABC Building Excellence Awards are judged by local authority building control surveyors: the project is nominated by the inspector who visited the site, and assessed on how it was built and how its technical problems were solved, not on the photographs. Bohun Grove was inspected throughout by the London Borough of Barnet's building control team.
The house and the brief
Bohun Grove was a typical interwar semi: hipped roof, bay window, a narrow kitchen at the back and a garden the house turned its back on. The brief was to make it a family home for the next thirty years — a kitchen, dining and living space opening onto the garden, a master suite in the roof, more bedrooms and bathrooms than the house was born with, and a garden that belonged to the house rather than sat behind it.
Rear extension with an open-plan kitchen, skylights across the new roof and full-height glazing onto the garden.
Hip-to-gable loft conversion — the sloping side of the roof rebuilt as a vertical gable so the loft runs the full width — with a master bedroom and en-suite shower room.
Two new bathrooms, enlarged bedrooms and new windows throughout.
Whole-house renovation behind the new work, and a landscaped garden designed with the extension so the inside and the outside read as one space.
What the judges were looking at
An extension and a loft built together on a semi touch everything structural at once: new foundations and steel at the back, new floor beams bearing into the party wall at the top, a roof rebuilt from hip to gable, and the existing house in between carrying all of it. The building control surveyor sees every stage of that — foundations, steel, roof structure, fire protection for a three-storey house, insulation, drainage — and the award recognises that it was done well at every one of them. It is the least marketing-led award a builder can win, because the person nominating you is the person who inspected you.
Anderson's advice
“Semi-detached hip to gable + rear dormer combos almost always fall under permitted development, but neighbours often object informally.” Bohun Grove is the case study for that sentence. The loft went through under permitted development with a Lawful Development Certificate; the extension and the party wall work still mean a neighbour living next to a building site for months. Talk to them before the scaffold goes up, show them the drawings, explain the party wall notice before it lands on the mat. On a semi, finishing with the neighbours still on speaking terms is part of what a good build looks like.
What Bohun Grove costs today
For anyone planning the same programme on a 1930s semi in 2026: a 20 m² rear extension is typically £46,000 – £62,000 inc. VAT, a hip-to-gable loft with rear dormer £60,000 – £114,000 inc. VAT (£50,000 – £95,000 + VAT), a new bathroom or en-suite £14,400 – £24,000 inc. VAT each, and a whole-house renovation behind it £60,000 – £180,000 inc. VAT (£50,000 – £150,000 + VAT) depending on how far it goes. Add the ranges in full; the final figure is postcode dependent. The instant estimate prices your own combination in two minutes and our cost examples show four priced jobs.
Two awards, one way of working
As LABC Building Excellence Award Winners 2024 for Best Residential Extension in London — and London Regional Winners again in 2026 for Best Conversion or Alteration to an Existing Home — the same team designed and built both projects: architectural design, structural engineering and construction under one contract, with the council's building control surveyor inspecting from the first trial pit to the completion certificate, a 12-month workmanship guarantee and a 10-year LABC structural warranty. See the Bohun Grove project page for the full photograph set, the Weech Road project page for the 2026 winner, and our awards and accreditations page for both.
What our clients say
“LCCL Construction were professional from start to finish. The team were trustworthy, reliable and delivered work to the highest standard.”
— KashImaging, Trustpilot
Frequently asked questions
What did LCCL win the LABC Building Excellence Award 2024 for?
Best Residential Extension in London, for Bohun Grove in East Barnet EN4 — a rear extension with open-plan kitchen, a hip-to-gable loft conversion, two new bathrooms and a whole-house renovation with landscaped garden, inspected by the London Borough of Barnet's building control team.
Who nominates projects for an LABC award?
The local authority building control surveyor who inspected the work. Judging is on build quality and how technical problems were solved, which is why the award is regarded as independent evidence of how a builder works.
Can I see Bohun Grove?
The full photograph set is on the Bohun Grove project page, and we describe it on every consultation call about an extension or loft on a semi-detached house. We never give out a client's address.
Get a figure for your own project
To book a free 30-minute consultation call about your extension or whole-house renovation, call LCCL Construction on 020 8037 7332 or get an instant estimate online — six questions, about two minutes, and you see a real range for your postcode on screen. Finchley N3 based, covering all of London and Hertfordshire.
One team, one contract, one point of contact — from first sketch to handover.
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