Loft Conversions
Loft conversions that add real space and real value.
Dormer, hip-to-gable, mansard and Velux loft conversions across London. Full structural engineering, planning coordination and build management under one accountable team.
Expert loft conversion specialists in London.
A well-executed loft conversion is one of the most cost-effective ways to add space and value to your home. The key word is well-executed — structural integrity, correct Building Regulations compliance, properly designed stairs and adequate headroom all matter enormously.
RCB manages loft conversions from structural assessment through planning, Building Regulations submission, full structural build, insulation, rooflight or dormer installation, staircase fit, internal fit-out and final sign-off.
We have completed dormer, hip-to-gable, mansard and Velux loft conversions across London. Whatever the type of conversion your property can accommodate, we will advise you honestly and deliver it properly.
What's included
How It Works
The RCB process for this service.
Structural Assessment
We assess your loft's suitability — headroom, roof structure, floor joist capacity and access.
Design & Approvals
Architectural drawings, planning or permitted development assessment, structural calculations and Building Regulations.
Estimate & Programme
A detailed, itemised estimate covering every element. A clear programme from site start to completion.
Build & Sign-off
RCB manages structural alterations, build-out, internal fit-out and Building Control sign-off.
Planning & Regulations
Most loft conversions in England fall under Permitted Development and do not require a full planning application — but this depends on your property type, location and the type of conversion. Building Regulations approval is always required. Structural calculations are always required. Fire safety, insulation, ventilation and means of escape must all be addressed. RCB coordinates all of this.
FAQs
Common questions.
What types of loft conversion are available?
The main types are: Velux (roof windows only — simplest and cheapest), Dormer (an extension projecting from the roof slope, adding headroom and floor area), Hip-to-gable (converting a hipped roof end to a vertical gable), and Mansard (a major structural alteration creating near-vertical rear wall). The right type depends on your property and budget.
How much does a loft conversion cost?
A simple Velux conversion can start from around £25,000–£35,000. Dormer conversions typically range from £40,000–£70,000+. Mansard conversions are the most expensive, typically £60,000–£100,000+. RCB provides a fully itemised estimate for your specific project.
Do loft conversions add value?
Yes — a well-executed loft conversion typically adds significant value, often exceeding the cost of the conversion in London and surrounding areas. The key word is well-executed: poor structural work, inadequate headroom or non-compliant fire protection will reduce or negate the value gain.
How long does a loft conversion take?
A Velux conversion typically takes 4–6 weeks. A dormer conversion typically takes 8–12 weeks. A mansard or full loft extension can take 12–20 weeks. Pre-construction (design, planning, Building Regulations) adds to this timeline.
Can I live in the house during a loft conversion?
Yes, in most cases. Loft conversion works are largely confined to the loft level and roof, allowing you to remain in the house. There will be disruption when the staircase is installed, but this is typically manageable.
Related services:
Ready to discuss your project?
Book a free project review or send your drawings for a detailed estimate.