If you are asking how much does a loft conversion cost in the UK, the honest answer is that the final price depends on far more than the size of the loft. The type of conversion, roof structure, access, staircase, plumbing, electrics, insulation, windows and level of finish all make a difference. As a rough guide, many UK homeowners may budget between £30,000 and £100,000 or more, although every project is different. A straightforward conversion in an accessible roof may cost less than a complex design requiring major structural alterations. For accurate pricing, request a free, no-obligation quote.
Typical UK loft conversion costs by type
The figures below are broad guide prices rather than fixed quotations. They can vary by region, specification, access and the condition of the existing house. Labour and material costs can vary between areas. Every project is different, so these figures should be treated as a starting point only; request a free, no-obligation quote for accurate pricing.
- Roof light conversion: as a rough guide, typically £30,000–£45,000. This can be a less disruptive option because the existing roof shape is largely retained. It may suit a loft that already has enough headroom and floor space, with roof windows added for light.
- Rear dormer conversion: as a rough guide, typically £45,000–£75,000. A dormer can extend the usable floor area and create more headroom, but it involves additional structural work, external cladding or roofing, windows and internal finishing.
- Hip-to-gable conversion: as a rough guide, typically £55,000–£85,000. This changes a sloping side roof into a vertical wall and can create more internal width. It is often combined with a rear dormer, which can increase the overall cost.
- Mansard conversion: as a rough guide, typically £65,000–£100,000 or more. This is a substantial alteration that can create a large room but involves significant structural and external work. Planning requirements and design complexity may also be greater.
- More complex or high-specification projects: £100,000 or above may be possible where the conversion includes extensive structural alterations, a bathroom, bespoke joinery, premium finishes or difficult access.
What is included in a loft conversion quote?
A proper quotation should explain what is included rather than giving one unexplained total. The design and preparation stage may include a measured survey, drawings, structural calculations and advice on whether planning permission or other approvals are likely to be needed. Some contractors include these items in the main price, while others list them separately, so it is important to check before comparing quotes.
Planning, design and approvals
Some loft conversions can be completed under permitted development rights, while others require a planning application. This depends on factors such as the proposed size, roof shape, position of extensions and the property’s location. A property in a conservation area, or one affected by local restrictions, may need additional consideration. Building regulations approval is separate from planning permission and addresses the technical requirements for the work. Ask your designer or contractor to identify which applications, drawings and inspections are included, and whether application fees are extra.
Structural work and access
Structural work is often one of the largest parts of the budget. A loft floor may need strengthening, new steel beams may be required, and the roof structure may need altering to create a clear room. The design of the staircase affects both cost and the layout of the floor below. A staircase may require changes to ceilings, flooring, doors, lighting or storage. Scaffolding, skips, temporary protection and site access should also be identified in the quote, as these costs can otherwise appear as surprises later.
- Insulation, plasterboard and fire-resistant construction where required for the design.
- Roof windows, dormer windows, external doors or larger glazing, including flashings and making good.
- Electrical installation, lighting, sockets, smoke or heat detection and any upgrades needed to the existing system.
- Heating and plumbing, particularly if you want an en-suite bathroom or a radiator in the new room.
- Plastering, painting, flooring, skirting, doors, ironmongery and built-in storage.
- Waste removal, scaffolding, protection of existing areas and final cleaning.
Common extras that can increase the final cost
The difference between an initial estimate and a final account can come from choices made after the project has started. An en-suite bathroom adds plumbing, drainage, ventilation, waterproofing, sanitaryware, tiling and electrical work. Moving a soil pipe or connecting new drainage can be more involved than expected. Premium roof windows, larger dormers, bespoke wardrobes, engineered timber flooring and high-end bathroom fittings can also raise the specification.
The condition of the existing roof and house matters too. Repairs to old coverings, chimney alterations, hidden timber decay, asbestos-containing materials, inadequate drainage or outdated electrics may not be visible during an initial inspection. Difficult access can increase labour, delivery and scaffolding costs. If the project is in a terraced or closely built-up property, protecting neighbouring buildings and managing deliveries may require additional planning. It is sensible to discuss an appropriate contingency for unforeseen work based on the property and survey findings.
How to compare loft conversion quotes
Do not choose a contractor on the headline figure alone. Check whether each quote covers design work, structural calculations, approvals, scaffolding, waste removal, insulation, windows, electrics, plumbing, decorating and flooring. Confirm the specification of doors, sanitaryware, sockets, light fittings and finishes, as allowances can make two apparently similar quotes very different. Also ask how variations will be priced if you change the design or if hidden defects are found.
A local renovation team can help you assess the whole project rather than treating the loft as an isolated room. BMB Renovation, based at 157 Judge Street, Watford WD24 5AN, carries out loft conversions alongside house renovations, bathroom fitting and renovation, carpentry, flooring, tiling, painting and decorating. Plumbing, tiling, electrical and cabinet installation work is handled in-house. Homeowners in Watford, Bushey, Rickmansworth, St Albans, Hemel Hempstead, Borehamwood, Harrow, Croxley Green, Luton and Bedford can review the wider renovation services or request a free, no-obligation quote.
Before committing, obtain a survey or feasibility assessment, decide what the room needs to achieve and set a realistic specification. A bedroom with roof windows will have a different budget from a dormer with an en-suite and fitted storage. The clearest route to an accurate figure is a site visit followed by a written, itemised quotation that explains assumptions, exclusions and possible extra costs.