The Mansard Loft Conversion That Adds A Floor

There is no single price, because the cost depends on your property and the work involved. A mansard is usually the largest investment of the loft conversion types, because the roof is rebuilt rather than adapted, and the figure is shaped by the scale of structural work, the design complexity and the specification you choose. Rather than quote a vague range, we visit your property, scope the project clearly and provide a written quote, usually within about a week. The cost is then split into staged payments tied to progress, with no large upfront deposit.

In most cases, yes. Because a mansard changes the shape of the roof significantly, it usually needs planning permission rather than falling under permitted development. That is not a problem to fear. We assess your property early, advise on the likely route and handle the planning process for you as part of the service. In conservation areas, a well-designed mansard can often be approved because it is drawn to respect the look of the street, and we factor in neighbouring properties and local constraints from the start so there are fewer surprises later.

A dormer is a box-shaped structure that projects from the existing roof slope, keeping most of the original roof in place. A mansard goes further. It rebuilds the roof slope into near-vertical walls with a near-flat top, which creates more headroom and far more usable floor space across the width of the property. In short, a dormer adapts the roof, while a mansard reshapes it. A mansard usually needs planning permission and involves more structural work, but it delivers the biggest transformation of the loft conversion options.

Terraced houses are some of the best candidates for a mansard. Many London terraces have tall, solid roofs and the kind of proportions a mansard is designed to make the most of. Because the reshaped roof can be drawn to follow the line of the street, it adds a full floor inside while sitting comfortably within a row of similar homes. Victorian and Edwardian terraces in particular tend to suit a mansard well. We assess each property individually for roof structure, head height and any planning considerations before recommending the right approach.

Yes. On many period terraces, an L-shaped mansard loft conversion combines the main roof with the rear outrigger to form an L-shape, which adds even more usable space and allows for more flexible room layouts. It is a particularly effective option for growing families who need a generous main bedroom along with additional space such as an en suite or study. Whether it suits your home depends on the existing roof and rear projection, which we assess as part of the design stage.

A mansard generally takes longer than a simpler dormer or rooflight conversion, because there is more structural work involved in rebuilding the roof. Rather than promise a timeline that depends on factors outside our control, we agree a realistic programme upfront and run organised teams to keep it moving. Most delays on any loft conversion come from late design changes or long lead times on specialist items, so we encourage key decisions early and explain anything that could affect the schedule. You receive a clear timeline as part of your quote.

A mansard creates a full additional floor with proper, usable rooms, which is the kind of space buyers and families notice. As well as improving day-to-day living, that extra accommodation can make a home more appealing when it comes to sell. The exact effect on value depends on your property, your area and the quality of the finished work, so we focus on delivering space that genuinely improves how the home works rather than making promises about specific figures. Done well, a mansard is space that earns its place.

Yes. The best way to understand what a mansard can do for your home is to see completed mansard loft conversion pictures and real projects. Our project pages show finished mansards across London, including work in conservation areas, so you can see the standard of design and finish before you commit. We are also happy to point you to nearby examples and to our reviews on Google and Houzz, and during a site visit we can talk through layouts and ideas using examples from past projects.