Mansards, L-shaped and rear dormers, hip-to-gable and rooflight conversions on London terraces, semis and period homes. One team does the lot, from the first survey to the day the staircase goes in.
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TrueBuild Loft Conversions turns unused roof space across London into bedrooms, bathrooms, offices and family space. We build mansards, L-shaped and rear dormers, hip-to-gable and rooflight conversions, fit new loft staircases, and rebuild existing loft rooms that were never done properly.
One team handles the strip-out, structure, carpentry, roofing, electrics, plastering and finishing, and we deal with the parts London adds to the job: borough planning rules, conservation areas, Article 4 directions, party wall notices and scaffold on a narrow street.
Which one suits your house depends on the roof shape, the head height and what the borough allows. Shaded areas show the new room each one creates.
The rear roof is rebuilt at a steep angle with a flat top, giving close to a full extra storey. The classic London answer where a dormer alone wouldn’t give enough room.
Good fit: Terraces wanting maximum space, usually with planning
More on Mansard conversionsA rear dormer wrapped around into the back addition, forming an L. Often enough for a double bedroom, a bathroom and a landing in one go.
Good fit: Victorian and Edwardian terraces with an outrigger
More on L-shaped dormersA box built out from the back slope, turning sloping ceiling into full-height wall and floor space. The most common conversion on London semis.
Good fit: Semis and terraces, bedroom plus shower room
More on Rear dormersThe sloping side of a hipped roof is built up into a vertical gable wall, making room for the staircase and a far bigger loft.
Good fit: 1930s semis and detached houses with hipped roofs
More on Hip-to-gableThe roof shape stays exactly as it is. We strengthen the floor, insulate and fit rooflights into the slope.
Good fit: Lofts that already have the height, and roofs facing the street
More on Rooflight (Velux) loftsSame roof, more moving parts. These are the things that decide whether a London conversion runs smoothly.
Large parts of London have permitted development rights removed, so work that would be automatic elsewhere needs an application here. We check your address before anything is agreed.
Several boroughs publish guidance on how a mansard should look, from the pitch of the front face to the windows used. Getting that right first time saves months.
The back addition on a Victorian terrace is what makes an L-shaped dormer possible, and it changes where the staircase and bathroom can go.
In a terrace you may be serving notice on two neighbours. Doing it early keeps the start date and keeps things civil.
Narrow streets, permit zones and shared alleys all affect how materials get in. It’s planned at survey stage, not left to the first morning.
Period roofs hide surprises: slipped slates, old purlins, previous alterations. We tell you what we find rather than quietly working around it.
A conversion is only as good as the stairs up to it and the bathroom in it. Both are planned from the start.
Designed around tight London landings, with spindles, handrail and balustrade.
Planned around head height and the existing soil stack, then tiled and finished.
French doors and frameless glass that open the back of the loft to the garden.
Cold, dated or unapproved loft rooms stripped back and rebuilt properly.
Word for word, unedited, from customers of TrueBuild Loft Conversions.
We had our loft conversion done by TrueBuild Loft Conversions in spring 2025. We had tried a few other local companies first but some wouldnt even come out to give us a quote so we contacted TrueBuild after being recommended by a friend.
Mark was helpful from the first phone call and came out the next day to have a look and give us a quote. We decided to go ahead with them and really glad we did.
Everyone who worked on the house was friendly polite and respectful which was a big thing for us as we have 2 young children and the house was basically a building site for a few months.
Everything went to the timescale Mark had given us and the price was what we had agreed at the start, no random extras suddenly getting added on halfway through. The work was all done to a really high standard and you could tell they werent cutting corners.
The loft has completely changed the house and looks exactly how we wanted it. Really happy with the end result and would definitely use TrueBuild Loft Conversions again.
If your wanting a loft conversion done properly by a team who actually turn up, respect your house and do a good job then id definitely recommend them.
Had our loft conversion done by TrueBuild Loft Conversions with a dormer and ensuite and honestly couldnt be happier with how its turned out.
From the start Mark was really helpful and explained everything to us properly, kept us updated and made the whole job feel a lot less stressful than we thought it would be.
Big thank you to Shane and Brad aswell who worked hard every day, always turned up on time and were respectful of the house. Plenty of coffees biscuits and the odd breakfast butty kept them going 😂 the finish on the dormer and ensuite is brilliant and you can tell they take pride in what they do.
Also want to mention Josh who was polite and worked hard throughout, a credit to the team.
Its completely changed the house for us and given us loads more space. Everyone was friendly tidy and reliable from start to finish.
Would definitely recommend TrueBuild Loft Conversions to anyone thinking about getting their loft done and we would use them again for future work without a doubt. Thanks again lads 😊
TrueBuild Loft Conversions completed some work for us in January 2026 and we couldn’t recommend them highly enough. We bought a house with an existing loft conversion, but the staircase was extremely awkward and unsafe to use. We honestly didn’t think there would be enough space to install a proper full-sized staircase.
The team came out, measured everything up and designed a new staircase complete with spindles, handrail and balustrade. The difference it has made is incredible and it has completely transformed the loft space while adding real value to the house.
Everyone involved was punctual, professional and very tidy throughout the job. The electrics were moved where needed and all the plastering was finished to a really high standard.
We would definitely use TrueBuild Loft Conversions again and would happily recommend them to anyone needing loft conversion or staircase work. Apologies for the delayed review we’ve been busy renovating the rest of the house!
Choosing TrueBuild Loft Conversions for our loft was definitely the right decision. From the first time we spoke to Mark everything was easy and straight forward and he was always helpful.
Mark and the lads were a brilliant team, Shane Brad and Josh all worked really well together and you could tell they knew what they were doing. From ripping out the old loft to the carpentry and building work everything was done really well and the attention to detail was spot on.
We changed our mind on a couple of things last minute aswell and they were always happy to help and never made it feel like a problem.
We stayed living in the house while the work was being done and honestly it wasnt anywhere near as bad as we expected. They cleaned up every day and always respected the house which made a massive difference.
You can tell they actually care about the work they do and wanted to make sure everything was how we wanted it. Really happy with how its all turned out and feel lucky we found them. Would definitely recommend TrueBuild Loft Conversions.
Excellent communication from start to finish and really happy with the work from Mark and the team. Hardly any disruption while the job was being done and Mark went out of his way to make sure everything ran smoothly.
Absolute pleasure to deal with and couldnt rate TrueBuild Loft Conversions highly enough. Thanks again lads!
A loft conversion means builders in your home for weeks. These are the things that make that bearable, in customers’ own words.
On a London street where scaffold, parking and deliveries all have to line up, start times matter. Customers say the team arrives when it said it would.
always turned up on time and were respectful of the house
The work area is cleared at the end of every day and the rest of the house is left alone, which matters when you’re working from home downstairs.
They cleaned up every day and always respected the house
Your quote follows a proper survey of your roof, so there’s far less room for surprises appearing halfway through.
the price was what we had agreed at the start, no random extras suddenly getting added on halfway through
Sockets in a better spot, a different tile, another rooflight. Plans move as the room takes shape and that’s normal.
We changed our mind on a couple of things last minute aswell and they were always happy to help
One point of contact from the first call through to handover, so you always know what happens next and when.
explained everything to us properly, kept us updated
Party wall notices flagged early, scaffold planned, and the street left tidy. It keeps the job moving and keeps you on good terms next door.
Hardly any disruption while the job was being done
Six stages from the first phone call to the day you move furniture in.
Tell us the type of house, roughly what you want up there and where you are. We’ll say straight away whether it sounds like a dormer, an L-shape or a mansard job.
We come out, measure head height, check the roof structure and work out where the staircase lands. Then you get the options and a price.
Layout, windows and finish agreed, then the planning route, Building Control and any party wall notices sorted before work starts.
Scaffold goes up, the loft is cleared, steels and the new floor go in, and the dormer or mansard is framed and made watertight.
Electrics, plumbing for the bathroom, insulation and plasterboard, then plastering ready for decoration.
Stairs, joinery and bathroom finished, Building Control sign-off completed, scaffold away and the house cleaned up.
Finished rooms, dormers from the garden and bathrooms squeezed into the eaves.
There’s no honest way to price a roof you haven’t seen. These are the factors that move the number most.
The four approvals that decide how a London loft conversion starts.
Where it still applies, a loft conversion can go ahead without a planning application provided it:
Much of London sits in a conservation area, and many boroughs have Article 4 directions that remove permitted development rights street by street. Flats and maisonettes never had them.
Where that applies, you need planning permission, and the borough’s design guidance shapes what the roof can look like. Mansards nearly always go through planning.
Required for every loft conversion, planning or not. It covers:
The completion certificate is what your buyer’s solicitor will ask for.
Terraces and semis almost always trigger it, because steels bear into the shared wall or the wall is raised. Neighbours get written notice, and notice periods run to a couple of months.
We raise it at the quote stage so it never becomes the reason your start date slips.
General guidance for houses in England, not legal advice. Rules vary between boroughs and street by street, so we check your address with the local planning authority’s records before anything is agreed. A Lawful Development Certificate is worth having if you go the permitted development route.
Something not covered? Call 020 3769 7040 and ask.
Cost comes down to the type of conversion, the size of your roof, access for scaffolding and materials, whether you need a bathroom up there, and the finish you want. A mansard on a Victorian terrace is a very different job to rooflights in a 1930s semi, so we price your house rather than publish a list.
Call 020 3769 7040 or send the form and we’ll arrange a visit.
Sometimes yes, often no. Permitted development allows up to 40 cubic metres of extra roof space on a terraced house and 50 on a semi or detached house, as long as the work doesn’t go beyond the roof slope facing the road or above the existing ridge.
London is the big exception though. Many streets sit in conservation areas or under an Article 4 direction, which removes permitted development rights, and flats and maisonettes never had them. Mansards in particular are usually a planning application. We check your address and borough before anything is agreed.
A mansard rebuilds the rear roof slope at a steep, almost vertical angle with a flat top, giving close to a full extra storey. London terraces suit them because neighbouring roofs are often already mansarded, and several boroughs have design guidance setting out exactly how they should look. They almost always need planning permission.
Most Victorian and Edwardian terraces have a rear outrigger, the narrow back addition over the kitchen. An L-shaped dormer wraps a rear dormer around into that outrigger, forming an L. It’s one of the biggest space gains available on a terrace, and often enough for a bedroom, a bathroom and a landing.
If you live in a terrace or semi and the work touches the shared wall, for example cutting in steel beams or raising the wall for a mansard, the Party Wall etc. Act 1996 applies and your neighbours must be given written notice. Notice periods run to a couple of months, so we flag it at the quote stage rather than the week before we start.
Yes, always, whether or not planning permission is needed. Building Control signs off the new floor and roof structure, the staircase, fire safety and escape route, insulation, ventilation and sound. Keep the completion certificate, because buyers’ solicitors will ask for it.
It depends on the type. A rooflight conversion is the quickest, and a mansard with a bathroom is the longest. You get a timescale with your quote, and customers tell us jobs have run to it.
Yes, most people do. The bulk of the work happens up in the roof behind a sealed-off ceiling until the staircase goes in, and the team cleans up each day. One customer put it this way: “We stayed living in the house while the work was being done and honestly it wasnt anywhere near as bad as we expected.”
Measure from the top of the ceiling joists to the underside of the ridge. Around 2.2 metres or more is usually a good starting point for a rooflight or dormer conversion. If you’re short of that, a mansard or a dormer that raises the usable height may still work, which is what the survey is for.
Yes. We plan it around head height, the waste run down to the existing soil stack and where the rooflight goes, so the shower ends up somewhere you can actually stand. On a terrace it often sits over the existing bathroom to keep pipework short.
We work across London, north, east, south and west, plus the outer boroughs. If you’re just outside the M25 and not sure, give us a ring and ask.
Call 020 3769 7040 or send the form. We’ll come out, measure up, check head height, the roof structure and where a staircase can land, then talk you through the options and price the job.
Looking for a loft conversion company near you? We work right across the capital. If your area isn’t listed, ring and ask.
Victorian terraces and semis where rear dormers and L-shapes do the most work.
Terraced streets with outriggers, ideal for L-shaped dormers.
Period terraces and 1930s semis, plenty of them in conservation areas.
Mansards and full-width dormers on classic bay-fronted terraces.
Wide roofs and hipped ends that suit hip-to-gable conversions.
Semis and detached homes with roof space going spare.
Tell us about your house and we’ll come out, measure up and show you what’s possible.
Quickest way is a phone call. Or send the form and we’ll call you back.
020 3769 7040 info@truebuildconversions.co.uk