Rear mansard conversions cost £65,000–£85,000 (fully inclusive of design, planning, and build). L-shaped mansards range from £75,000 to £95,000. Front and rear (double) mansards cost £85,000–£130,000 or more, depending on size and specification. All Simply Loft prices are fixed-price after survey — no retrospective variations for agreed scope.
>> How much does a mansard loft conversion cost in London in 2026?
