Loft Maker London
Mansard Loft Conversions in London and Essex
A mansard changes the whole roof profile, giving full headroom and a large, regular floor area - the most complete conversion you can get from an existing footprint.
A mansard roof has two slopes on each side: a shallow upper slope and a steeper lower slope. That shape is the point of it. The steeper lower slope creates a near-vertical wall inside the roof space, which means full headroom across almost the whole floor, and inset windows in the slope rather than sitting in the plane of the roof.
It is the most complete loft conversion you can achieve without moving the foundations, and for a house with a substantial roof space and a traditional London or Essex elevation it can look entirely original. It is also the most demanding. The lower slope may come close to or above the height of the existing ridge, the structure has to carry considerably more load, and it almost always needs a full planning application rather than permitted development.
Planning is usually required
A mansard adds a substantial volume of roof space, and the steeper lower slope is very likely to take part of the roof above the height of the existing highest point. Where it does, the work cannot be permitted development under Class B and needs a householder planning application.
In practice, a mansard is judged on its appearance: whether the proportions suit the house and the street, whether the ridge and eaves heights are in character with the surrounding roofscape, and whether the materials match. In a conservation area or under an Article 4 direction that judgement is made with local character firmly in mind, so early advice is worth having. Waltham Forest, which covers Chingford and South Woodford, has conservation areas with Article 4 directions, and the Highams Park estate is an Area of Special Character with its own direction, so this is a real consideration locally rather than a theoretical one.
Structure and steelwork
A mansard introduces new vertical loads close to the eaves of the existing roof, plus a new ridge. The existing trusses are normally replaced or heavily reinforced with a structural steel frame, and the new load is carried down through the walls to foundations that were designed for a much lighter house. That is a calculation, not a detail, and it is where our structural steelwork comes in.
Where the existing walls cannot take the new load, an intermediate steel beam or a distributing structure may be needed. We would rather find that out at design stage with a calculation than on site with the roof already open.
Inset windows and the internal room
Mansard windows are set into the slope, usually in small dormer-like surrounds, which keeps them out of the plane of the roof and preserves the profile when you look at the house from the street. They still need planning permission in most cases, and their design is usually settled early because it is the most visible part of the work.
Inside, the near-vertical lower slope means the ceiling follows the upper slope but the walls are full height, so the room reads as a proper room. That is the argument for a mansard: you are not making the best of a difficult shape, you are replacing the shape.
What is included, and how long it takes
Design and drawings, planning application, structural engineering and steel fabrication, building regulations, demolition and rebuilding of the roof, roofing, windows, plastering, electrics, plumbing, heating, decoration and the completion certificate. A mansard is usually programmed together with any other work to the house, and on-site time is typically ten to sixteen weeks depending on the size and the access. Every project carries a 10-year structural warranty.
Related services
- Loft Conversions London & Essex — Turn unused roof space into a bedroom, bathroom or home office. We handle design, consents, structure and the build.
- Structural Steel Installation London — Beams, posts and frames that let you take out a load-bearing wall or open up a plan, calculated by an engineer, fabricated and installed by us.
- Side Extensions London & Essex — The side return is usually the most under-used space on a London plot. Filling it with a well-designed extension is the cheapest way to add a proper room.
Frequently asked questions
Is a mansard conversion allowed under permitted development?
Rarely. A mansard adds a lot of volume and its steeper lower slope often rises above the existing highest point of the roof, which is one of the permitted development limits. In most cases a full householder planning application is needed.
Does a mansard conversion need structural steel?
Almost always, yes. The new roof introduces vertical loads that the existing structure was not designed for, so the trusses are typically replaced or reinforced with a steel frame and the loads are carried down to foundations designed for a lighter building.
Will a mansard make my house look taller?
Yes, in profile, and that is the main planning consideration. A well-proportioned mansard in the right materials reads as part of a traditional building; an over-tall one reads as an extra storey. We design the ridge and eaves heights to suit the house and the street rather than to maximise the volume.
Is a mansard worth it compared with a dormer?
A mansard gives you substantially more usable floor area and a better-shaped room. A dormer is a smaller, cheaper intervention that solves the headroom problem in a specific place. Where the roof space is large and the existing hipped ends are awkward, a mansard is often the better long-term answer.
Does a mansard roof need planning permission?
Usually yes. A mansard roof changes the overall shape and volume of the dwelling, which generally requires planning permission, and it may also be restricted in conservation areas. We prepare and submit the application as part of the project.
How much space does a mansard roof add?
A full mansard roof can add a substantial floor, often comparable to a rear extension, because the space sits within the existing footprint. The trade-off is that it is more involved than a simple loft conversion and takes longer, so it suits projects where the extra volume is the priority.
What does Loft Maker London do?
We are a London and Essex construction company specialising in loft conversions, dormer and mansard roof construction, side extensions, GRP flat roofing and structural steelwork. We handle design, planning, structural engineering, groundworks, roofing and finishing in-house, so you deal with one team from first drawings to handover.
Which areas do you cover?
We work across London and Essex, including Chingford and South Woodford. We are a mobile, service-area business, so we come to you rather than asking you to visit an office.
How much does a loft conversion cost?
It depends on the property, the specification and how much of the work is structural. A straightforward conversion in an existing roof space costs less than one that needs a new structural opening, steelwork or extensive roof construction. We price every project individually and give you a clear written quote before work starts, so there is no ambiguity about what you are paying for.
Do I need planning permission for a loft conversion?
Not always, but it depends on the property and the work. Many loft conversions fall within permitted development, while mansard roofs, dormer windows in conservation areas, and work that changes the volume of a dwelling often need planning permission. Building Regulations approval is a separate requirement and applies to most structural work. We assess your specific property, tell you exactly which permissions are needed, and handle the applications.
How long does a loft conversion take?
A conversion that does not require planning permission is often built in two to three weeks on site, but the full project - surveys, designs, approvals, build and finishing - takes considerably longer. Projects involving a mansard roof, an extension or steelwork take longer again. We give you a realistic programme with the quote, and we keep you informed if anything changes.
Is my project covered by a warranty?
Every project we complete is backed by a 10-year structural warranty. The full policy wording and schedule of cover are issued to you at handover, so you know exactly what is covered and what to do if you need to make a claim.
Do you handle Party Wall notices?
Yes. Where your project affects a neighbouring property, Party Wall notices or an award may be required before work starts. We prepare the necessary paperwork, serve the notices and coordinate with the adjoining owner's surveyor where one is appointed.
Can you work from drawings we already have?
Yes. If you have planning approval, architectural drawings or structural calculations, we can price and build from them. If you would rather we took the design and planning on as well, we can do that instead - just tell us which stage you have reached.
Can you match an existing roof or extension?
Yes. We work with a range of roof tiles and finishes, and we match existing materials where we are extending or building alongside original fabric, so the finished work reads as part of the house rather than an addition to it.
What happens after I get in touch?
We arrange a free, no-obligation consultation at your property. We look at the space, discuss what you want to achieve and any constraints, and then come back to you with options and a clear written quote. There is no obligation to proceed.
Tell us about your project
Send a few details and we'll come back to you with honest advice on what is possible, what it involves and how long it takes.