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.
Construction-ready · Build from your drawings · London & Hertfordshire
Already have drawings? We'll price them — a fixed price in 7 working days, and a start the week after signing
By Anderson & the LCCL Construction Team
Finchley N3 · Design & build, LABC award winners 2024 and 2026
You have done the hard part: the architect, the planning decision or Lawful Development Certificate, perhaps the structural calculations too. What you need now is a builder who prices the drawings as drawn, at a fixed figure, and can start. Send us the set and we come back within seven working days of the call with a fixed price for the scope on the drawings. If the job is ready, we can usually be on site the week after the contract is signed. Your architect stays your architect, your engineer stays your engineer — we build to their documents.
Quick answer
Fixed price for the scope on your drawings, within 7 working days of the call. As a guide, permitted development lofts from £56,400 inc. VAT (£47,000 + VAT) and extensions from £42,000 inc. VAT (£35,000 + VAT), postcode dependent.
Yours — already in hand. We build to your approved drawings; we can add the Lawful Development Certificate or building-regulations submission if they are still outstanding.
7 working days to a fixed price; start usually the week after signing; 4–12 weeks on site for a loft or single-storey extension.
Send the drawings to info@lcclconstruction.co.uk or bring them to a free 30-minute call.
Price
Fixed, within 7 working days of the call
Start
Usually the week after signing, if the job is ready
Your team
Your architect, engineer and party wall surveyor stay yours
Guarantee
12-month workmanship guarantee; 10-year LABC structural warranty
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 we need from you, and what you get back
The more of the set that is done, the faster the price. Nothing here is a design fee — we price what is drawn.
Planning permission decision or Lawful Development Certificate (or tell us it is pending)
Architect's approved drawings — plans, sections, elevations
Structural engineer's calculations and drawings, if done (we can commission them if not)
Party wall position — notices served, awards in place, or not started
Building-regulations drawings, if done (we can submit full plans through LABC if not)
Your preferred start date and any constraints on site
You get back: a fixed-price proposal for the scope on the drawings, itemised, with what is excluded stated plainly
A programme with the start date and the weeks on site
One contract, one point of contact, LABC inspections booked, and the completion certificate at the end
What a construction-ready job costs
Your price comes from your drawings, not from a table. These are the fixed-price guide figures for the permitted development projects we price most, economy specification, inc. VAT with the ex-VAT figure in brackets.
Project
What it gives you
From
Velux / rooflight loft
Light, a small room or storage; uses almost none of the PD allowance
£32,400 inc. VAT (£27,000 + VAT)
Rear dormer loft (terrace or semi)
Double bedroom and shower room in 6–8 weeks
£56,400 inc. VAT (£47,000 + VAT)
L-shaped dormer loft (terrace with outrigger)
Two rooms and a bathroom from the 40 m³ allowance
£58,800 inc. VAT (£49,000 + VAT)
Hip-to-gable + rear dormer (semi)
The full semi-detached loft: bedroom, bathroom, proper stair
£60,000 inc. VAT (£50,000 + VAT)
3 m rear extension (4 m detached)
Open-plan kitchen-diner, 15–20 m²
£42,000 inc. VAT (£35,000 + VAT)
Side-return infill (terrace)
A full-width kitchen under a glazed roof
£42,000 inc. VAT (£35,000 + VAT)
Single-storey side extension (semi)
Utility, wider kitchen or shower room where the garage or path was
£42,000 inc. VAT (£35,000 + VAT)
Garage conversion
Single attached garage to one habitable room, internal works plus the front wall
£21,600 inc. VAT (£18,000 + VAT)
Planning-route step-ups
When you need them
Guide range
Mansard loft
When a dormer or hip-to-gable will not give the space — almost always a planning application
£76,800 – £148,800 inc. VAT (£64,000 – £124,000 + VAT)
10–14 wks
Wraparound extension
Rear and side in one scheme — falls outside permitted development
£72,000 – £153,600 inc. VAT (£60,000 – £128,000 + VAT)
10–14 wks
6–8 m rear extension
Prior approval route: 42-day neighbour consultation instead of a full application
£60,000 – £90,000 inc. VAT (£50,000 – £75,000 + VAT)
10–12 wks
What the fixed price includes: everything drawn — structure, roof, glazing openings, insulation, first and second fix to the specification on the drawings, LABC inspections and the completion certificate. If your drawings specify a higher finish, the price follows the drawings.
What moves the price: the postcode; what the drawings actually show (a bathroom in a loft, steels to open the back wall); anything the set leaves to us to choose, which we price as separate lines; and anything still outstanding — calculations, building-regulations submission, party wall — which we can take on and price separately.
Is your job construction-ready? The five things we check
The approval is in hand
Planning permission granted, or a Lawful Development Certificate issued. If it is still with the council we can price now and start when it lands.
The drawings match the approval
The set we price is the set the council approved. Changes after approval may need a fresh application — we tell you before we price.
The structure is designed, or we add it
Calculations and steel drawings from your engineer, or we commission them. We never price a loft or extension without them.
Party wall is settled, or started
Notices served and awards agreed on a terrace or semi. If not, we serve notices the week we sign — two months before a start.
The site is ready to start
Access agreed, the garden or front clear for scaffold and skip, and a start date you can commit to.
Approvals
Who is responsible for what
Your professionals remain responsible for their documents. We are responsible for the build.
Item
Who
What it means
Architect's drawings
Your architect
The design, the planning or Lawful Development Certificate application and any council conditions stay with the practice that drew them
Structural calculations
Your engineer (or ours, if you ask)
The steel sizes and connections; building control relies on them, and so do we
Party wall awards
Your surveyor (or ours)
Notices, awards and the schedule of condition for the neighbours
Building regulations
Shared
We build to the approved drawings and book every LABC inspection; full-plans submission is yours or ours, whichever is quicker
The build
LCCL Construction
Fixed price for the scope on the drawings, programme, site management, inspections, handover and guarantees
Fixed price
What fixed price means on a construction-ready job
The price is for the scope on the drawings we have priced, itemised line by line. It does not move unless the drawings move or you ask for something that is not on them, and then you see the change before it happens. There is no design fee and no re-drawing of your architect's work. Payment is a booking fee on signing, then staged payments against the Schedule of Works — each stage invoiced when the previous one is complete.
If part of the set is missing — calculations, building-regulations drawings, party wall — we can take it on. It is priced as its own line so the build price stays the build price.
Recent lofts and extensions we built
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: read the exclusions before you compare prices
Three builders pricing the same drawings should land close together. When one is far lower, it is almost always what has been left out — the steels priced as a provisional sum, the glazing as a client supply, the party wall and building control as somebody else's problem. Ask every builder for the exclusions list before you compare the totals. Ours is on the proposal, in plain English, and the figure on it is the figure you pay.
How a construction-ready job runs with LCCL
From the drawings landing in our inbox to the completion certificate.
DAY 0
Send the drawings, book the call
Email the set to info@lcclconstruction.co.uk or book a free 30-minute call. We read the drawings before we speak.
DAYS 1–7
Site visit and fixed price
We visit, check the drawings against the house, and send a fixed-price proposal with the programme and exclusions within seven working days of the call.
WEEK 2
Contract and start date
Booking fee on signing reserves the start window. Party wall notices served now if not already in place.
ON SITE
4–12 weeks
Scaffold up on day one; LABC inspections at each stage; one point of contact throughout; completion certificate and guarantees at handover.
“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
Construction-ready questions
Yes. Most construction-ready jobs come with a set from an independent practice. We price what is drawn and build to it; the architect remains responsible for the design and the approval.
We commission them from a chartered engineer and price them as a separate line, usually £450 to £8,000 depending on the job. The build cannot be priced properly without them.
If the approvals, drawings and party wall are in place, usually the week after the contract is signed. If something is outstanding, the start follows the last item — party wall notices need two months.
Yes, for the scope on the drawings. It changes only if the drawings change or you add something that is not on them, and you see the change before it happens.
We can give a guide from the drawings, but the fixed price follows a visit — the house always has something the drawings do not show.
Yes — if you do not have drawings yet, our design and build service takes the project from the first sketch. See the permitted development projects for fixed-price lofts and extensions with no planning application.
On a terrace, a side return gives you width in the existing kitchen for the least money and usually no planning application; a rear extension gives you depth and a proper dining space. If the budget stretches, a wraparound does both under one contract and one scaffold. Our free consultation call is the quickest way to settle it for your house.
An extra reception or a bigger kitchen-diner is the improvement most London buyers pay for. Our house-extension value guide sets out what the data shows by area. We are not valuers, so treat any figure as indicative and talk to a local agent before you commit.
Where we build from your drawings
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. The 1930s semis of Barnet, Enfield, Harrow and the Hertfordshire towns are hip-to-gable country; the Victorian terraces of Haringey, Waltham Forest and South London are where the L-shaped dormers and side returns go.
Send the drawings, get a fixed price.
Email the set to info@lcclconstruction.co.uk or book a free 30-minute call. 020 8037 7332, Mon–Sat 08:00–18:00.
One team, one contract, one point of contact — from first sketch to handover.