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Slate mansard roof with dormer windows above a red-brick and stone London mansion block

Loft Conversion, Designed and Built

A finished top floor for a period townhouse in prime London, from the first drawing to the last fitting.

Craftex

100% of projects delivered ahead
of programme and on budget

London homes we have rebuilt

  • 12 weeksto design and refurbish a 400 sq m top-floor penthouse at Kensington Olympia
  • 0site visits the Kensington Olympia owner needed to make
  • 0snags or defects at the Kensington Olympia handover
  • £10Mpublic and employers' liability cover on every home we build

A new top floor, finished like the rest of the house

Craftex designs and builds loft conversions in London: mansard, dormer and hip-to-gable, with the structure, the new stair, fire safety and the en-suite included. The team that draws your loft conversion prices it and builds it, so the figure and the date agreed at design are the ones you get. For prime London homes and period townhouses, a loft conversion is a structural job on a lived-in house, and we run it like one.

Most loft conversions in London are sold as a box on the roof. We build you a floor: a bedroom, a bathroom and storage that look as if they were always part of the house, finished to the standard of the rooms below.

Our designers, site managers and about 60% of the trades on our sites are our own people, so the person who measures your loft in the survey is the person who answers for the finished room. The drawings, the steel calculations, the Building Regulations application and the party wall notices all run through one team. That is how we work on prime London homes, and a loft gets the same attention to joinery, plaster and light as a drawing room.

Loft bedroom under exposed oak roof trusses with a stone fireplace, a wide-plank floor and an antique cupboard

Mansard, dormer or hip-to-gable: which loft fits?

London period townhouses in stock brick with white stucco window surrounds and dormers in their slate mansard roofs

Three things decide it: the head height you have, the shape of your roof and whether the street sits in a conservation area. A rear dormer suits most townhouses, a hip-to-gable opens a hipped detached or semi-detached house, and a mansard gives the biggest room where planning allows it.

Read more

Head height first. Measure from the top of a ceiling joist to the underside of the ridge. Around 2.2 m is the usual working minimum for a comfortable loft room; below that, the options are lowering the ceiling of the room underneath or raising the roof, and both need a structural design.

Permitted development or a planning application. A rear dormer or a hip-to-gable on a house can often be built under permitted development (Class B), within 40 m³ of extra roof space on a terraced house and 50 m³ on a semi-detached or detached one. The rights do not apply to flats, to houses in a conservation area or where an Article 4 direction removes them, and the dormer must not face the road. We recommend a Lawful Development Certificate before work starts, so a buyer's solicitor has proof later. See permitted development rights in London.

Mansard loft conversion. A mansard replaces the back slope, and sometimes the front, with a near-vertical wall clad in slate and set with windows. It gives the most usable floor area and follows a pattern London planners know, but it almost always needs a planning application. Our guide to the mansard roof covers the design rules boroughs apply.

Dormer loft conversion variants. A full-width rear dormer, an L-shaped dormer over the back addition of a Victorian townhouse, or two smaller dormers on a pitched roof: each changes the room you get and the route to consent.

Fire escape and the protected stair. A loft room on a two-storey house adds a third storey, so Building Regulations Part B asks for a protected escape route: fire-resisting doors to the habitable rooms on the stair and mains-wired, interlinked smoke alarms. The new stair needs 1.9 m of headroom at its centre line, under the loft rules of Part K.

Choosing between loft conversion companies in London. Specialist loft firms, general builders and design-and-build contractors all quote for lofts. Ask who draws it, who carries the structure and who signs off the fire route, and whether they are one company or three.

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What does our loft conversion service include?

Six parts of one loft, drawn, built and signed off by the same team, so you never chase three firms for one answer. Each loft is designed around the house below it. Where the new stair lands decides the bedroom layout on the floor under it, the plumbing route decides where the en-suite goes, and the roof structure decides how much of the slope can become storage. For a whole-house project, our luxury home renovation service runs the loft with the rest of the work.

Row of white-framed mansard dormers on a slate roof with a London roofscape beyond

Mansard loft conversions

A near-vertical slate wall and a full-height room at the back of the house, designed to the borough's mansard rules.

Two gabled dormer windows with white frames set into a patterned slate roof

Rear dormer lofts

A full-width or L-shaped dormer that turns a sloping loft into a standing-height bedroom and bathroom.

Painted brick gable end of a house with an arched loft window and a chimney stack

Hip-to-gable lofts

The sloping side of a hipped roof built up into a gable wall, so the stair lands where you can stand.

Narrow white stair rising to a loft landing, lit from above

Structure, steels and new stair

New floor joists, steel beams designed by the engineer and a stair that sits over the one below.

Staircase seen from above with white balusters, a dark handrail and a herringbone landing

Fire safety and Building Regulations

A protected escape route, fire doors and interlinked alarms, inspected and certified by Building Control.

Dressing room lined with dark wood cabinets, lit shelves and a cove-lit ceiling

Bedroom, en-suite and storage fit-out

Plastered, insulated and finished rooms with an en-suite and eaves storage built into the slopes.

How does a loft conversion run with us?

01

Loft survey

We measure the loft, the roof timbers and the stair below, and tell you which type of loft fits and why.

02

Design and agreed price

Drawings, structural calculations and a fixed figure from the team that will build it.

03

Planning, permitted development and party walls

The planning application or Lawful Development Certificate, Building Regulations and the notices to your neighbours.

04

Build: scaffold, roof and stair

Scaffold and a temporary roof go up, the new structure goes in from outside, and the stair opening is made late.

05

Sign-off and handover

Building Control completion, the fire and electrical certificates, and a finished floor handed to you.

The Craftex Residential Design and Build Guide, shown as a printed book

The Craftex Guide to Residential Design and Build

What to settle before you appoint anyone for work on your home: the brief, the consents, the budget, the programme and the questions that tell a fixed figure from a hopeful one. Free, and a short read.

Six promises, written into your contract

Each of these is a clause in the contract for your loft, not a line in a brochure.

  1. One team from drawing to handover

    The people who design your loft build it, so nothing is lost between a designer and a builder.

    At Kensington Olympia we ran the whole job from conception to completion.

  2. A price fixed at design

    The structure, stair and fire route are designed before you sign, so the agreed figure holds.

    Pan Peninsula finished within its allocated budget.

  3. Dates in the contract

    Steels, windows and the stair are ordered as soon as the drawings are signed off, and the programme is part of the agreement.

  4. Neighbours told first

    Party wall notices, delivery times and scaffold access agreed before day one.

    At Herbert Crescent noise, access and protection were planned before anyone arrived.

  5. Covered for you and your neighbours

    Professional indemnity on request, ISO and CHAS accreditation, and site safety run to our own management system.

  6. Signed off, then looked after

    Building Control completion and every certificate in your file, then a 12-month defects period on the work.

A builder's quotation on a desk with a note saying send it to us, we'll beat it

Already have a quote? Send it to us. We'll beat it.

Holding a loft company's price, or a builder's quote for someone else's drawings? Send it to us. We come back the same working day with a better figure for the same loft, the same structure and the same finish.

Where do loft conversions go wrong?

Five places a London loft goes wrong, and what we settle at the survey so none of them happens in your house. Almost every one of these starts with the same cause: the loft was sold before anyone designed it. A survey and drawings that come before the price close the gaps.

AreaWhere it often goes wrongWith Craftex
Head heightThe room is measured after the floor goes in and comes up shortFinished height checked at the survey, before the design is drawn
Stair positionA stair squeezed in late eats a bedroom on the floor belowStair drawn first, so both floors are planned together
Fire routeEscape route left to Building Control to find at inspectionProtected stair, fire doors and alarms designed in from the first drawing
Steel accessBeams that cannot reach the roof without opening the houseSteel sizes and the delivery route through the roof planned before ordering
Party wallNotices served late, so work stops while neighbours appoint surveyorsNotices served at design stage, with time for the statutory notice period

What sets the price of a loft conversion?

Six things move the figure for any London loft. Each one is fixed in the design before you agree a price.

What moves the priceWhat we fix before you agree
Loft type: dormer, hip-to-gable or mansardThe type that fits your roof, your street and the room you need
Roof structure and steelsEngineer's calculations and steel sizes, priced from the drawings
Stair and fire routeWhere the new stair lands and how the escape route is protected
Bathroom or en-suiteWhere the soil pipe runs and how the water reaches the top floor
Glazing and rooflightsWindow sizes, rooflights and any doors to a terrace, specified
Scaffold and accessScaffold design, a temporary roof and the delivery route for materials

A loft inside a bigger renovation shares scaffold, structure and services with the rest of the house, which changes the sums. Our guide to house renovation cost in London shows how a whole-house budget comes together.

Free cost calculator

What will your loft conversion cost?

Enter the floor area of the new loft room and choose the type. You see an indicative build range straight away, based on our 2026 London rates, ex VAT.

Your estimateEnter your spaceex VAT and fees Get a fixed figure

The range covers construction only: drawings, planning and party wall surveyors' fees sit outside it. Your fixed figure follows the loft survey and the drawings, from the team that will build it.

Loft conversions across London

White stucco London townhouses with bow fronts, tall windows and black iron balconies

Period townhouses: Belgravia, Chelsea, Kensington and Notting Hill. Mansards and full-width dormers on stucco and brick townhouses, built from the scaffold while the family stays in.

Red-brick Kensington townhouses and mansion blocks with gables and bay windows facing a tree-lined street

Conservation areas: Hampstead, Highgate and St John's Wood. Mansards and roof alterations that need planning consent, drawn to the borough's rules for the street.

Read more

We convert lofts on prime London homes, including Belgravia, Chelsea, Kensington, South Kensington, Notting Hill, Holland Park, Hampstead, Highgate, Primrose Hill, St John's Wood, Islington, Clapham, Wandsworth, Fulham, Chiswick, Richmond and Wimbledon. Many boroughs publish design guidance for roof extensions and mansards, and we draw every loft to it. If you are comparing loft conversion companies in London or loft conversion specialists for a period townhouse, the team is the same wherever your home is.

Our team

  • in

Loft conversions: your questions

Do I need planning permission for a loft conversion?

Often not for a rear dormer or hip-to-gable on a house, which can fall under permitted development within the volume limits. A mansard, any loft in a conservation area or on a flat, and any front dormer usually need a planning application. We check the route at the survey.

Is my loft tall enough to convert?

If the clear height under the ridge is about 2.2 m or more, most lofts convert without touching the roof line. A lower loft can still work if the ceiling below drops or the roof is rebuilt; we tell you which at the survey.

What is the difference between a mansard and a dormer loft?

A dormer is a box built out of the existing roof slope. A mansard rebuilds the whole slope as a near-vertical wall with windows, so it gives more full-height floor area but almost always needs planning permission.

How long does a loft conversion take?

It depends on the type: a mansard rebuilds the roof, so it takes longer than a rear dormer. We give you the programme with the fixed figure, and the dates go into the contract.

Can we stay in the house during the work?

Usually yes. The structure goes in from the scaffold under a temporary roof, and the opening for the new stair is made near the end, so the floors below stay in use for most of the job.

Where will the new stair go?

Over the existing stair wherever possible, so it takes the least space from the floor below. We draw it at the survey stage, because its position sets the loft layout and the headroom under Part K.

What fire safety does a loft conversion need?

A safe way out from the top floor to the front door. In most houses that means the stair is enclosed, every room opening onto it gets a fire door and the alarms are linked on every floor; open-plan layouts need an alternative agreed with Building Control.

What drives the cost of a loft conversion?

The type of loft, the roof structure and steels, the stair and fire route, the bathroom and the scaffold. Use our calculator above for a range at our 2026 rates, then get in touch and we will discuss your project.

Do you convert lofts in conservation areas?

Yes. Permitted development rights for lofts do not apply there, so we prepare a planning application drawn to the borough's guidance for roof extensions on that street.

How fast do you reply?

We reply the same working day. Tell us the street and what you want from the top floor, add a picture of the roof if you have one, and one of our directors calls you back.

What our clients say

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  • I and my husband are very satisfied with Craftex's service and customer support. We bought a house in Hampstead and wanted to redesign and renovate it. On our initial free consultation with Sviat, we found out that we actually can do loft conversion and rear extension and add value to the property straight away.
    We worked with the Craftex design team to bring our vision to life and deliver planning approvals. At that time guys started stripping out to save time on the construction programme as we wanted to move in ASAP.
    We worked with very experienced project director Konstantin who was responsible for all aspects of project delivery from design to construction with a very good eye on details and customer care.
    We saved a lot of money by having professional advice from the start. Project management and quality at Craftex are at the highest level. Many thanks to Craftex Team.

    Lia Lavryk

  • Very professional company. Craftex did brilliant minimalistic design and completely refurbished my apartment to the highest quality.

    Vlad

  • Amazing experience with these guys. I trusted them my apartment in London and Business. They are always accurate, very professional, responsive and neat. They would always advice me right things for my best interest. I had luxury experience with them and I would definitely recommend Craftex to everyone.

    Motush Motushev

  • Great experience from start to finish. Communication was clear, the workmanship was excellent, and the whole project was managed professionally.

    Rhea Langford

  • Hired Craftex for our conversion project. We had to convert a 600m2 office into 8 apartments. Guys did an excellent job in terms of program efficiency and quality of the finishes which gave us a big upside to exit the project 2 months faster than other competitors’ timelines.

    Misha Levit

  • I’d like to thank the team at Сraftex for the work they did on our office.
    It was really important for us to get the work done quickly, but without compromising on quality, as we regularly have clients and guests visiting and needed to move into the new office within a month.
    We spent around two weeks discussing and agreeing all the details before the work started. What I really appreciated was that everything we agreed beforehand was actually followed through during the job. The work was also completed on time.
    Thanks to the whole Сraftex team for a great job. I’d definitely use them again if we need any work done in the future.

    IURII PYLYPETS

  • We recently worked with Craftex and honestly couldn’t be happier with the results. From start to finish, the team was professional, reliable, and highly skilled. The quality of workmanship exceeded our expectations, and everything was completed on time and to a very high standard.
    Communication throughout the project was excellent, and they always went above and beyond to make sure we were satisfied. It’s rare to find a construction company that combines professionalism, attention to detail, and great customer service so well.
    Without a doubt, Craftex is one of the best construction companies we have ever worked with. Highly recommended to anyone looking for quality and trustworthy builders.

    Adam Miah

  • Craftex has completed a range of both small and large-scale projects on our commercial property with exceptional precision and quality. Dmitriy consistently delivers courteous, prompt service and has shown great flexibility in accommodating last-minute changes to plans and timelines. I highly recommend Craftex for their professionalism and outstanding workmanship.

    Pascal Hunt

  • Great company to work with as always. Super flexible at dealing with evolving requirements and fast deployment and execution.

    Akshay Khanna

  • Hired Craftex to do the full design and fit out of my gym in Chelsea. Super efficient and fast team. They gave the best price and a proper fast track program. We managed to open in less than 6 weeks with no headaches or surprises during construction. Quality was great, we had zero snags on completion. I’ve worked with a few companies before but these guys really impressed me from project management to how they treat the client. Top GGs.

    Александр Хоменко

  • I worked perfectly with Sviat and Joe, with their architect they came up with a very smart design for our office to fit more desks and optimise the space to its maximum capacity. They also did excellent value engineering on the MEP design proposed by others, allowing us to save around £50K. The quality and speed were outstanding we finished two weeks ahead of schedule. Highly recommend these guys.

    John Smith

  • Happy with the end result. Tight timeline but they pulled it off. The team worked late shifts and even weekends to help us open the doors on schedule. Site was always left tidy at the end of the day and no surprise charges either. Good communication throughout. Would definitely use Craftex again.

    Pawel Kamionka

  • Highly recommended!
    Craftex are the kind of fit-out contractors in London you can truly trust. From the very first meeting, they understood our vision and gave practical ideas to make the most of our space. They turned our old storage area into a clean, efficient, and well-organized warehouse. The team was professional, easy to work with, and clearly took pride in their work.

    Monika Kamionka

  • We brought in Craftex to refurb our London office and honestly, they made the whole thing way easier than we expected. They listened, suggested ideas we wouldn’t have thought of, and explained everything clearly. Not the cheapest quote we got, but the end result shows why, the place looks modern, clean, and our team actually enjoys being here now. Communication was spot-on too. No chasing and confusion, deadlines were hit. If you want people who genuinely care and don’t treat your project like “another job,” I’d recommend them.

    A Google User

  • Sviat and his team at Craftex were brilliant to work with on our office redesign. From the first meeting, they took the time to understand how we actually use the space rather than just pitching generic solutions. They came back with clever, practical ideas to maximise use of the space and get more employees and desks inside . Every step was handled professionally, and the process felt surprisingly smooth for a project of this size. They finished one week ahead of schedule, and the transformation is clear — our office feels brighter, more functional, and much more welcoming. I’d happily recommend Craftex to anyone who wants a reliable design team that also makes the journey enjoyable.

    Cucu Iulian

  • We recently worked with Sviat and the Craftex team on a complete warehouse refurbishment, and the results have been outstanding. From the very beginning, their team was professional, organized, and attentive to every detail. The project was completed on time and within budget, without disrupting our day-to-day operations.

    Simone Racaku

  • My experience with Craftex was excellent from beginning to end. They took the time to really listen to what I wanted and then offered practical suggestions that made the design even better. I always felt like they cared about creating a space that worked for me, not just one that looked nice on paper. The end result is an office that feels stylish, welcoming, and very functional for day-to-day work. The process itself was straightforward, well-managed, and never stressful. I’d definitely recommend Craftex if you’re looking for office design and build services in London — they made the whole journey a positive one.

    Ion Bounegru

  • I’m really pleased with my experience working with Craftex. As a commercial construction firm, they handled everything from start to finish without any unnecessary stress on my side. What impressed me was how they suggested practical ideas that improved the design while also keeping things realistic. The communication was always clear, so I never felt out of the loop. The project ran smoothly, deadlines were met, and the end result is exactly what I was hoping for — a space that feels both functional and modern. It’s not easy finding contractors who are this reliable, but Craftex definitely proved they can be trusted.

    Taron Papoyan

  • I had an amazing experience working with Sviat and the Craftex team on our office fit-out in London. They were always professional, responsive, and quick to offer the best advice whenever decisions needed to be made. I really appreciated how they balanced style with practicality — the office doesn’t just look fantastic, it works perfectly for our team. Everything was done with care and attention to detail, and the project never felt overwhelming because they managed it so well. Communication was clear from start to finish, and I always felt involved in the process. I would happily recommend Craftex to anyone looking for a trustworthy contractor.

    Artur Dvorak

  • Craftex carried out a warehouse fit-out for us, and I couldn’t be happier with the outcome. The space has been completely transformed into a highly organized and efficient environment that makes our daily operations much smoother.
    The team was professional but also very approachable — I always felt comfortable asking questions or giving feedback. They came up with smart, practical solutions that worked perfectly for our setup, and everything was explained clearly along the way.
    The best part was how they stuck to the agreed timeline, finishing on schedule without cutting corners. It’s rare to get both quality and reliability, but Craftex delivered both.

    Roma Shchukin

  • We’re extremely happy with Sviat and the Craftex team’s work. They suggested clever ideas, managed the project efficiently, and delivered a functional, modern space. The team was easy to communicate with and very professional throughout the process!

    Polina Lysenko

  • I can honestly say our office has been completely transformed thanks to Craftex. From the very first meeting, the team was approachable, professional, and full of creative ideas that really made sense for our business. They didn’t just focus on how the space would look but also how it would work for the team day-to-day. The new layout is efficient, modern, and welcoming, and you can tell they really thought about the details. The whole process was smooth and surprisingly stress-free. They kept me updated at every stage, which gave me confidence. I’m really happy with the results and wouldn’t hesitate to recommend them to anyone.

    Mykyta Khadzhynov

  • The results from Craftex’s commercial refurbishment in London are fantastic. The team was friendly, clear in communication, and made sure the project stayed on track. The workspace now feels efficient, welcoming, and modern. Definitely a team you can trust!

    Alaa Betar

  • We hired Craftex for a commercial ground floor fit-out with 2 flats above. There were some minor co-ordination hiccups with third-party suppliers but the team kept it moving. Finish quality was strong. Kitchens and doors look great. I have already asked them for a quote on the next project.

    Ben Edell

  • These guys actually deliver. They handled our first industrial to residential conversion near Tower Bridge, turned an old warehouse into 4 modern flats. They stuck to the plan, kept the site clean and the timing was on point. No hidden extras, no drama, just a professional construction company in London that gets the job done.

    Богдан Главацкий

  • We recently hired Craftex for a commercial office fit-out project in Central London, and overall, we’re really happy with the result. There was a delay on our side with a custom glass partition supplier, but the Craftex team managed the construction schedule very professionally and kept everything on track. Their guys worked clean, respected our workspace and IT setup, and kept the site tidy throughout. If you're looking for a reliable office refurbishment company in London, I’d definitely recommend Craftex. Would use them again without hesitation.

    Ardian Beleshi

  • This was a full high-end renovation of my Victorian rental apartment in Westminster, just off Sloane Square and Belgravia. The scope included full fit-out: electrics, plumbing, a new bespoke kitchen, and a luxury bathroom refurbishment. Craftex took care of everything and made the process easy. They weren’t the cheapest, but you can tell they really know what they’re doing when it comes to prime London property renovations.
    The team was professional, organised, and genuinely seemed to care about getting everything right. I was especially impressed with the quality of the finish – the attention to detail really shows in every corner.
    I’m very happy with the results and would definitely recommend Craftex to anyone looking for reliable, high-quality renovation work in Central London.

    Наталия Цимбалюк

  • I was stressed about timing since we had bookings lined up, but they smashed it. Even worked Saturday to finish the floor. My clients love the look — the beauty salon fit-out turned out exactly how I wanted. Couldn’t have pulled it off without their help. Genuinely appreciate the way they communicated throughout the refurbishment. If you need reliable help with beauty salon design or fit-out, especially in a place like Chelsea — these are the guys.

    Rami Jusupova

  • We used Craftex for a shop-to-flat conversion in Chelsea — turning an old retail space into two rental units. Access wasn’t the easiest, but the guys handled it well, no drama. Quote was clear, no hidden extras, and they actually stuck to it, which is rare. Finish came out solid, exactly what we needed for rentals. Joe (PM) kept things ticking and communication was always on point. All in all, smooth job — would use them again for sure.👍

    Apartify Estates

  • Fuse Energy hired Craftex on the fit-out and installation of our engineering and research centre, which included electrical, heating, lighting, plumbing, and ventilation upgrades. They delivered everything to a high standard and were proactive throughout — even working weekends to help speed up the programme, despite not being contracted to. They managed last-minute changes very well, communication was clear and consistent, and the team was professional from start to finish. We’d happily recommend Craftex to anyone needing a reliable construction partner.

    Hainro Eybers

  • Holistic therapy space fit-out
    Super impressed. I had a very specific vision for the studio. calm tones, soft lighting, hidden storage etc. the craftex team just got it. build was done quicker than I expected and the guys were polite, tidy and actually listened. we had 2 snags on day one but they fixed it before the week was out. worth it for the peace of mind.

    Dariia Shvyryda

  • Made a full refurbishment and redesign of our Central London office. Fantastic work, quality service and reliable people. Can recommend it to everybody

    Nikita Nigai

  • Could not be HAPPIER with Sviat and the Craftex team, they certainly showed me that they’re the number one office design company in London that we’ve had the pleasure of working with. They gave us a unique design just like we wanted, and we loved the first initial draft of the concept. Also have to give them props for Construction, I gave them a tight timeline as we needed to move our team in ASAP, so they pulled double shifts and I didn’t see a drop in quality. Will be to talking to the team when we move up to our next bigger office. Highly recommended A+++

    Mikhail Burdoev

  • ISO 9001
  • ISO 14001
  • ISO 45001
  • CHAS
  • Constructionline Gold
  • SafeContractor
  • TrustMark
  • FMB
  • NICEIC
  • NAPIT
  • MCS
  • CSCS
  • Considerate Constructors
  • RICS, Royal Institution of Chartered Surveyors
  • RIBA, Royal Institute of British Architects
  • ARB, Architects Registration Board
  • Public & Employers' Liability £10M
  • Professional Indemnity £10M
  • ISO 9001, 14001 and 45001 certified

Tell us about your loft

Send the address and a few photos of the loft and the roof. We will come back to you the same working day.

Unit 5, 160 Buckingham Palace Road, London SW1W 9TR

info@craftex.co.uk

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