Transparent, honest pricing for every conversion type. Updated for 2025 — covering all London property types.
Prices below are Prime Loft fixed prices for London properties in 2025, inclusive of architecture, structural engineering, all planning applications, full build and 10-year structural warranty. No extras, no variation orders.
| Conversion Type | From | To | Best Suited To | Disruption | Planning | Key Benefit |
|---|---|---|---|---|---|---|
| Velux / Roof Light | £28,000 | £45,000 | Any | Low | Permitted Dev. usually applies | Minimal — no structural roof change |
| Standard Dormer | £36,000 | £58,000 | Any | Low–Medium | Permitted Dev. usually applies | 1–2 new bedrooms, bathroom |
| L-Shaped Dormer | £45,000 | £75,000 | Victorian/Edwardian terrace | Medium | Permitted Dev. usually applies | 2 bedrooms + bathroom from one project |
| Hip to Gable | £44,000 | £80,000 | Semi-detached/detached | Medium | Usually Permitted Dev. | Maximises width on end properties |
| Mansard | £55,000 | £130,000 | Any (especially period) | Higher | Full planning often required | Near-vertical walls, maximum floor space |
| Bespoke/Central London | £90,000 | £300,000+ | Prime central postcodes | Highest | Listed building consent possible | Conservation area specialists required |
Unlike many loft conversion companies, Prime Loft's quoted price includes everything required to deliver your completed loft — from first pencil line to final handover.
Full measured drawings, elevations and interior layout plans produced by our in-house architectural team.
Full structural calculations for every element of your conversion — included as standard.
We manage all applications, communications and approvals with your local authority on your behalf.
All structural works, roofing, insulation, plastering, electrics, plumbing, staircase, decoration and snagging.
Official Completion Certificate issued by the local authority on project handover.
Independent-insurance-backed structural warranty covering every Prime Loft conversion.
A well-executed loft conversion is consistently the highest-return home improvement a London homeowner can make. Adding a bedroom and bathroom typically adds 15–25% to a property's market value — often £80,000–£250,000 depending on location and specification.
Compare the cost of a loft conversion — from £42,000 — against the typical cost of moving in London: stamp duty, agent fees, conveyancing and removals alone often total £30,000–£80,000, before you've even found the right property.
Never. The price we quote is the price written into your contract. We carry every risk of unforeseen issues — not you. In 15 years of operation, we have never issued a variation order to a client.
The main factors are: conversion type (velux to mansard), property size and configuration, roof structure complexity, specification level (mid-range to premium), conservation area status and local authority planning fees.
No. Your 10-year structural warranty is included. Building Regulations and planning approval costs are included. There are no annual fees or hidden charges of any kind.
Yes. We operate a staged payment structure linked to project milestones — typically deposit, structural completion, first fix, second fix and handover. We work with several lending partners who offer finance for loft conversions.
Our quoted prices are exclusive of VAT. VAT at the standard rate of 20% applies. New builds and certain conversions may qualify for reduced-rate VAT — we advise on this at quotation stage.
We'll visit your property and provide a written, itemised fixed price that never changes.
Book Free Survey or call 0208 123 4567Our fixed prices cover architecture, planning, full build and 10-year warranty. No extras. Ever.