The Real Cost of a Loft Conversion in London (2026)

A well-planned loft conversion can add a bedroom, a home office or a light-filled principal suite without the upheaval of moving. Yet the first question most homeowners and developers ask is the hardest to answer neatly: what is the real loft conversion cost in London in 2026? The honest answer is that it depends on the type of conversion, the age and structure of the property, and the level of finish you are aiming for. As a London main contractor with more than 30 years of experience across new builds, flat conversions and high-end refurbishments, Berati Construction has seen how the right early decisions keep a loft project on budget and on programme.

What Drives the Loft Conversion Cost in London

Several factors shape the loft conversion cost in London before a single tile is lifted. The type of conversion is the biggest lever — a simple rooflight scheme sits at one end, a full mansard at the other. Structural work matters too: strengthening floor joists, forming new steels and altering the roofline all add cost. Access, party wall considerations and the age of the building play their part, as period roofs often hold surprises. Finally, the specification — bespoke joinery, en-suite bathrooms, underfloor heating and premium glazing — can move a budget considerably. Indicative London figures in 2026 tend to range from around £40,000 for a modest rooflight conversion to well beyond £100,000 for a large mansard with high-end finishes, though every property warrants a site-specific quote.

Types of Loft Conversion and What They Cost

The main formats each carry a different price. A rooflight (Velux) conversion is usually the most economical, as it works within the existing roof. A dormer adds headroom and floor area and sits in the middle of the range. A hip-to-gable, common on semi-detached and end-of-terrace homes, extends the roof slope to create usable space. A mansard — often required in conservation areas and on period terraces — reshapes the whole roof and delivers the most space, but is the most involved and therefore the most expensive. Choosing the right format for the property, and for its planning context, is where an experienced contractor earns their fee.

Where a Loft Conversion Adds the Most Value

For homeowners in prime and inner London, a loft conversion is rarely only about cost — it is about the value and quality it adds. A carefully detailed principal suite or a bright top-floor studio can transform how a home lives and how it sells. For developers working on flat conversions or new-build schemes, cleverly planned loft space can add a saleable bedroom or an extra unit. In both cases, the finish is what separates an ordinary loft from one that commands a premium, which is why we treat the build and the detailing with the same care as our luxury refurbishments and basements.

Every loft is different, and the only reliable figure is one based on your property and your ambitions. Berati Construction delivers loft conversions, extensions and full refurbishments across London, backed by ConstructionLine Gold, CHAS, NHBC and Gas Safe accreditations. Explore our services, see our recent projects, learn more about us, and contact us for a site-specific quote and a clear, considered plan for your loft.