Signature Build Properties is a trusted loft conversion London specialist — delivering dormer loft conversion London, Velux loft conversion London, hip to gable loft conversion London and mansard loft conversion London. Furthermore, a loft conversion bedroom London adds 20–25% to your property value, making it one of the best-return home improvements available. We manage planning, structure and the full build under one fixed price.
We design and build all loft conversion types for London properties — from a straightforward Velux loft conversion London to a full mansard loft conversion London. In fact, our structural engineers and project managers handle every stage from survey through to the finished loft bedroom.
A dormer loft conversion London is the most popular type in the capital — a box-shaped structure projecting vertically from the existing roof slope, adding full headroom and maximum usable floor space. Furthermore, most dormer loft conversions qualify under Permitted Development so loft conversion planning permission London is not required. Ideal for terraced and semi-detached homes across London.
A Velux loft conversion London is the most cost-effective option — adding large roof windows flush with the existing roofline without any structural changes to the roof. As a result, it is the fastest and most affordable loft conversion London route, almost always permitted development. Moreover, Velux windows flood the space with natural light, making even compact lofts feel bright and spacious.
A hip to gable loft conversion London converts the sloped hip end of your roof into a vertical gable wall — dramatically increasing the usable floor area and headroom of the loft. It is by far the most popular loft conversion type for semi-detached and detached London properties. Furthermore, it is often combined with a rear dormer to create the maximum loft conversion bedroom London footprint.
A mansard loft conversion London is the most ambitious and most space-efficient type — transforming the entire rear roof slope into a near-vertical wall topped with a flat roof. In short, it adds the equivalent of a full new storey to your property. However, mansard loft conversions require loft conversion planning permission London and are most common in central London and conservation areas.
What is loft conversion cost London 2025? See typical costs for all loft conversion types below. All prices are based on current London build costs and include structural works, insulation, electrics and standard finishes. We provide fixed-price contracts after every free site survey.
Loft conversion cost London 2025 ranges from £28,000 for a Velux loft conversion London to £100,000+ for a full mansard loft conversion London. Consequently, a well-executed loft conversion bedroom London typically adds £80,000–£140,000+ to a London property value — making it one of the best-return investments available to homeowners in the capital.
| Conversion Type | Typical Cost | Build Time | Planning |
|---|---|---|---|
| Velux Loft Conversion London | £28,000 – £45,000 | 6–8 weeks | Permitted Development |
| Dormer Loft Conversion London | £45,000 – £70,000 | 8–12 weeks | Usually PD |
| Hip to Gable Loft Conversion London | £55,000 – £75,000 | 10–14 weeks | Usually PD |
| Hip to Gable + Rear Dormer | £65,000 – £90,000 | 12–16 weeks | Usually PD |
| Mansard Loft Conversion London | £70,000 – £100,000+ | 12–16 weeks | Planning Required |
| En Suite Bathroom in Loft | £8,000 – £18,000 | Add 2–3 weeks | Included in build |
| Loft Staircase Installation | £3,000 – £8,000 | Included | Part of build regs |
All prices are indicative for London 2025 and include structural works, insulation, joinery, electrics and standard finishes. We provide a fixed-price written contract after every free survey.
From your first call to the finished loft bedroom — here is how our loft conversion London team delivers every project from survey through to building regulations sign-off, managed under one fixed price.
To begin with, our project manager visits your property, checks head height, structural integrity and access options. Furthermore, we assess which loft conversion London type suits your property and advise on loft conversion planning permission London requirements — all completely free.
Following the survey, our architectural team produces full drawings and structural calculations. Where loft conversion planning permission London is required, we manage the full planning application. For Permitted Development projects, we submit a Lawful Development Certificate on your behalf.
Once planning is confirmed and the design is agreed, you receive a written fixed-price contract covering every element of the loft conversion London — from structural steelwork to the finished, decorated loft bedroom. In short, the price never changes from the quote.
Our team carries out all structural works — new floor joists, steel beams, roof alterations and dormer or mansard structure. Consequently, a building control inspector visits at key structural stages to verify compliance throughout the loft conversion London build.
All insulation, staircase installation, first fix electrical and plumbing works are carried out before boarding and plastering. As a result, the loft conversion bedroom London is fully insulated, wired and plumbed before any finishing begins — no shortcuts, no snags.
Finally, the building inspector issues your completion certificate. At that point, we carry out a full snagging walk-through with you, resolve any items and issue your written workmanship guarantee. Your new loft conversion bedroom London is ready to use from day one.
Our loft conversion London price includes everything — from planning and structural engineering through to the finished, decorated, signed-off loft bedroom. In fact, there is nothing left for you to arrange separately.
"Dormer loft conversion London on our Victorian terrace in Ealing — master bedroom with en suite and two Velux windows. Signature Build managed the planning, structure and full fit-out. Finished in 11 weeks, fixed price throughout. The loft has transformed our home."
"Hip to gable loft conversion in Hillingdon — combined with a rear dormer to create a huge loft bedroom and en suite. Signature Build handled the permitted development certificate, structural engineering and the complete build. Fixed price, on time, brilliant finish."
"Velux loft conversion London — the most cost-effective way to add a bedroom. Signature Build checked the permitted development rules on the first visit and confirmed no planning was needed. Completed in 7 weeks and adds huge value to our property."
Our loft conversion London team will visit your property, check suitability, advise on the best conversion type and handle all loft conversion planning permission London requirements. You receive a written fixed-price contract covering everything — from planning to the finished loft bedroom.
Contact us today to discuss your project and receive a no-obligation quote.
