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.
Planning · London & Hertfordshire
Planning permission for extensions, lofts, basements and new builds in London: how it works in 2026
By Anderson & the LCCL Construction Team
Finchley N3 · Design & build, LABC award winners 2024 and 2026
Planning is the part of a building project you cannot compress, and the part most people get wrong by starting the drawings before checking the address. This page explains the three routes — permitted development, prior approval and a full application — which projects take which, what the council charges, how long each takes, and how we run it so that nothing starts on site until it is signed off.
Quick answer
Council fees at cost: Lawful Development Certificate £274, prior approval £249, householder application £548 from April 2026. Drawings, submission and approvals are in the design and build price.
Single-storey extensions and most lofts are permitted development; wraparounds, two storeys, mansards, basements, new builds, flats and conservation areas need a full application.
LDC up to 8 weeks · prior approval 42 days · householder application 8 weeks · new build 8–13 weeks; plus 2–6 weeks of design before submission.
A free 30-minute phone call with our team, no obligation.
Routes
PD · prior approval · full application
Householder fee
£548 from April 2026
Decision
8 weeks statutory
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
Which projects need planning permission?
The usual route for each project type on a house outside a conservation or Article 4 area. Flats always need a full application.
Project
Usual route
Decision time
Full application (cellar refit within the footprint may be PD)
8 wks + basement impact assessment
Council fee (England, 2026)
Amount
Notes
Householder planning application
£548
From 1 April 2026, plus the Planning Portal service charge
Lawful Development Certificate — proposed works
£274
Half the householder fee; the document your buyer's solicitor asks for
Larger home extension prior approval
£249
6 m / 8 m single-storey rear; 42-day decision
Pre-application advice
Set by each council
Worth it where the borough engages; we tell you before you pay
How we run planning, start to finish
One team for the drawings, the application, building regulations and the party wall — and the build that follows.
Stage
What happens
Typical time
1. Address check
Conservation area, Article 4, listed status, flats, previous extensions, Green Belt in Hertfordshire — the route before you pay for a drawing
Day 1
2. Survey and design
Measured survey, drawings, and the choices that decide the route (depth, height, materials)
2–6 weeks
3. Pre-application advice
Where the borough engages — we know which do because we apply every month
4–6 weeks where used
4. Submission
LDC, prior approval or full application; design statement and precedent search where they help
—
5. Decision
Up to 8 weeks; conditions discharged before we start
6–13 weeks
6. Building regulations
Full-plans drawings and structural calculations to LABC — the inspector checks a design already approved
Alongside
7. Party wall
Notices 2 months before works to a shared wall, 1 month for excavation within 3 m / 6 m; most neighbours consent
Alongside
8. Start on site
Only when every approval is in
Week 12–24
Every council is different on top of the national rules. Each borough sits its own design guide on the permitted development baseline — how deep a rear extension can go on a full application, whether a 45° daylight test is applied, how dormers are judged, which conservation areas have lost permitted development under Article 4. We keep all 27 councils we work in on one page: planning rules by council.
Fees at cost: a householder planning application is £548 from 1 April 2026 plus the Planning Portal service charge; a Lawful Development Certificate for proposed works is half that; larger home extension prior approval is £249. Building-control charges are set by each council. Party wall notices £300 each; a surveyor only if a neighbour dissents (from £750 per neighbour). The figure on your itemised estimate is the figure you pay — nothing is added afterwards.
What LCCL does for you at the planning stage
Design and build inclusive — the drawings, the application and the approvals are in the price.
Address check before the first drawing — conservation area, Article 4, listed status, flats, previous extensions
Measured survey of the house and garden
Architectural drawings to the standard the council validates first time
Lawful Development Certificate or planning application, prepared and submitted for you
Pre-application advice where the borough is helpful (we tell you if it is worth the fee)
Design and access statement, precedent search and neighbour drawings where they help
Building-regulations drawings and structural calculations by our chartered engineer
Party wall notices served on your behalf (£300 each, at cost)
LABC full-plans approval, inspections and completion certificate
One project manager for the paperwork and the build — nothing starts on site until it is signed off
12-month workmanship guarantee; 10-year LABC structural warranty
Projects we took through planning
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
%2C%20founder%20of%20LCCL%20Construction.jpeg)
ANDERSON · FOUNDER, LCCL CONSTRUCTION
Anderson's advice: book the design stage in summer, build in autumn
August is our slowest month for project starts — most families delay until the schools go back. That makes it the best time to get the survey, drawings and approvals done: you go through the council queue while everyone else is on holiday and start on site in September or October with the paperwork finished.
Approvals are the part of the programme you cannot compress. Design and planning typically take 8–16 weeks; leave them to the last minute and the build slips into the following year.
“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
“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
Planning questions we get asked most
Planning is about whether you may build it — size, appearance, effect on neighbours — and is decided by the council's planning department. Building regulations are about whether it is built properly — structure, fire, insulation, drainage — and are checked by building control (LABC on our jobs). Every extension and loft needs building regulations approval, whether or not it needs planning.
The council can serve an enforcement notice requiring the work to be altered or removed, and an unauthorised extension is a problem when you sell. For permitted development the answer is a Lawful Development Certificate; for anything else, an application before the first brick. We do not start on site without the approvals in hand.
8–16 weeks from survey to a decision for a house extension or loft, 12–24 weeks for a two-storey extension, basement or new build. Design and planning are the part of the programme you cannot compress — start them in summer to be on site in the autumn.
A council order that removes permitted development rights in a defined area, usually a conservation area. In an Article 4 area even a small rear extension or a rear dormer needs a planning application. We check the council's Article 4 schedule for your address before the first drawing — it changes the route, the fee and the timescale.
A certificate from the council confirming that your extension or loft is permitted development and does not need planning permission. It is optional in law but we obtain one on every permitted-development project: it costs half the householder fee, takes up to 8 weeks, and it is the document your buyer's solicitor will ask for when you sell.
Not if it is permitted development within the limits — there is no consultation. On a prior-approval (6 m / 8 m) extension the council notifies the adjoining neighbours and only an objection triggers an assessment. On a full planning application neighbours can comment and the officer weighs daylight, outlook and privacy. Talk to them first; we will show them the drawings with you.
No. Flats and maisonettes have no permitted development rights for extensions or lofts, so every project is a planning application — and usually the freeholder's consent as well. We handle both.
Where we take projects through planning
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 extensions: East Barnet EN4, Finchley N3, Putney SW15, Mill Hill NW7, Wood Green N22 and Borehamwood WD6.