Mansard Loft Conversions in London & North London.
The most spacious loft conversion type — ideal for conservation areas and properties wanting maximum room.
What is a mansard loft conversion?
A mansard loft conversion involves replacing the entire rear roof structure with a near-vertical rear wall — typically at 72 degrees — and a flat roof. The result is the most spacious of all loft conversion types, with full-height walls across the entire width of the property. Mansard conversions are particularly common in London's conservation areas — including Hampstead, Highgate and East Barnet — where the strict design requirements of a mansard can be more sympathetic to the streetscape than a standard dormer. Because they involve significant changes to the roof structure, mansard conversions always require planning permission. Our team manages the entire application process.
Why choose a mansard in a conservation area?
Many of North London's most desirable streets — in Hampstead, Highgate, Muswell Hill and parts of Barnet — fall within conservation areas where planning restrictions limit what can be built. Mansard conversions, with their near-vertical rear wall and flat roof, are often the preferred option for planners in these areas because they minimise the visual impact on the streetscape. We have extensive experience obtaining planning permission for mansard conversions in conservation areas across North London and can advise on the likelihood of approval for your specific property.
Common questions
Does a mansard loft conversion always need planning permission?
Yes — mansard conversions always require full planning permission because they involve significant changes to the roof structure. We manage the entire planning application process on your behalf.
How long does a mansard conversion take?
A typical mansard loft conversion takes 14–20 weeks from start to finish. The planning application process typically takes 8–10 weeks before construction begins.
Are mansard conversions worth the extra cost?
Yes — mansard conversions deliver more usable space than any other loft conversion type, and in North London's high-value property market, this additional space typically adds 20–30% to the value of your home.
How much will your project cost?
Get an instant cost estimate for your extension, loft conversion, renovation or new build — tailored to your project in under 60 seconds.
Planning a mansard conversion in London?
Book a free, no-obligation consultation. We'll visit your home, listen to your brief and tell you honestly what's possible.
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