How much does a loft conversion cost in London?
Most homeowners looking into a loft conversion have the same first question: what is this actually going to cost? It is a fair one, because loft conversion prices in London vary significantly depending on your roof, your property type, and the finish level you choose. This guide gives you realistic 2026 figures to work with before you start getting quotes. For most homes in East and North London, the cost of a loft conversion sits between £30,000 and £95,000. A standard dormer, which is by far the most popular choice, typically falls in the £45,000 to £65,000 range for a bedroom and en-suite.
Loft conversion prices by type in London
Velux loft conversion: £30,000–£40,000
The most affordable option. Skylights are fitted into the existing roof slope without altering the roofline, which keeps costs and build time low. Works best where there is already sufficient headroom in the loft. If budget is a priority and your roof structure allows it, this is the natural starting point.
Dormer loft:
£45,000–£65,000
The most popular choice across London's Victorian and Edwardian terraces. A dormer extends vertically from the existing roof slope, creating a box-shaped addition with full-height walls and a significant increase in usable floor space. Most homeowners use a dormer loft conversion to add a master bedroom with en-suite bathroom.
L-shaped dormer:
£65,000–£95,000
Common in Victorian terraces with an existing rear outrigger. Two dormers join in an L-shape over the main house and rear extension, creating a larger layout with space for multiple rooms. A popular choice for families who want a bedroom, bathroom, and a proper landing from a single conversion.
Hip-to-gable:
£50,000–£75,000
For semi-detached and end-of-terrace homes with a hipped roof, where the roof slopes on all four sides. Converting the slanted hip end to a vertical gable wall substantially increases the internal volume. Often combined with a rear dormer for maximum space gain.
Mansard loft:
£70,000–£95,000
The most substantial structural conversion available, common on terraced houses across Inner London. The existing roof slope is rebuilt to a near-vertical angle, effectively adding a full extra floor of headroom and space. The higher mansard loft conversion cost reflects the structural complexity and the planning permission this type typically requires.
Bespoke loft: £80,000+
For properties that need a tailored architectural solution, often combining two or more conversion types. Most common in heritage buildings, conservation areas, or homes with unusual layouts. Cost depends on the design and specification.
Frequently asked questions
Comparing loft conversion quotes?
f you are getting quotes for a loft conversion in London, it is important to compare more than the final price. A lower quote may not include the same level of structural work, insulation, staircase design, bathroom fitting, windows, scaffolding, Building Control requirements or finish.
Before choosing a loft conversion company, check exactly what is included, what is excluded and how any changes will be priced once the work begins. Items such as steelwork, roof alterations, plumbing, electrics, plastering, decoration and bespoke joinery can make a significant difference to the final cost.
At LLAC, we help homeowners understand the full scope of their loft conversion before the project starts, so the quote is clear, realistic and suited to the property. Whether you are planning a dormer, mansard, hip-to-gable or L-shaped loft conversion, we can talk you through what to look for and what is achievable for your budget.
Get a loft conversion quote in London
LLAC works with homeowners across East and North London, including Hackney, Waltham Forest, Islington, and Haringey. Whether you know what you want or are still working out what is possible for your property, the next step is a conversation.