If you are asking “how much does a loft conversion cost?”, a sensible UK budget for 2026 is usually £35,000 to £80,000.
A simple rooflight conversion may cost less. A large mansard with an en-suite, complicated structural work and premium finishes can cost considerably more.
These are guide prices, not quotes. The final figure depends on your roof, property, location, access, finish level and the type of conversion you choose.
How much does a loft conversion cost in the UK in 2026?
Short answer: Most UK loft conversions cost between £35,000 and £80,000 in 2026. Rooflight conversions sit towards the lower end. Dormers, hip-to-gable projects and mansards cost more because they involve greater structural work, more materials and longer construction times.
| Conversion type | Typical 2026 guide price |
|---|---|
| Rooflight or Velux conversion | £22,000–£45,000 |
| Rear dormer conversion | £40,000–£70,000 |
| Hip-to-gable conversion | £45,000–£75,000 |
| Mansard conversion | £60,000–£95,000+ |
The figures above are broad UK guidance. They may include labour, materials, standard fixtures and VAT, but you should always check exactly what a contractor has included.
A small loft used as a home office will not cost the same as a full bedroom with a bathroom. Nor will a straightforward project in a detached house necessarily match the cost of work on a narrow London terrace.
Which type of loft conversion is cheapest?
Short answer: A rooflight, or Velux, conversion is usually the cheapest because it keeps the existing roof shape. A rear dormer costs more but creates more usable headroom. Hip-to-gable and mansard conversions involve larger changes and usually require higher budgets.
Rooflight or Velux conversion
A rooflight conversion works within the existing roof. It normally involves:
- Installing roof windows
- Adding insulation
- Strengthening the floor
- Fitting a staircase
- Adding electrics and heating
- Finishing the walls and ceiling
A typical budget is £22,000 to £45,000.
This option can work well when the roof already has enough height and space. It may suit a bedroom, office or hobby room, but the sloping roof can limit furniture placement.
Rear dormer conversion
A rear dormer extends the back of the roof to create a box-shaped section. It gives you more headroom and floor area than a rooflight conversion.
Expect around £40,000 to £70,000 for a typical rear dormer. Adding an en-suite, higher-spec windows or premium finishes can move the project towards the top of that range.
Hip-to-gable conversion
A hip-to-gable conversion changes a sloping side roof into a vertical wall. It is common on semi-detached and detached houses with a hipped roof.
The guide range is usually £45,000 to £75,000, particularly when combined with a rear dormer. It can create a much larger master bedroom or suite, but it adds structural work and may create planning complications.
Mansard conversion
A mansard changes a large part of the roof into a near-vertical structure. It maximises internal space and is common on terraced properties.
A realistic starting range is £60,000 to £95,000 or more. Mansards usually involve major roof work, more complex design and full planning permission.
What makes a loft conversion more expensive?
Short answer: The biggest cost drivers are the conversion type, structural changes, property size, access, location, plumbing, windows, finishes and whether the roof needs strengthening. A survey is the only reliable way to understand how these factors affect your specific home.
The main price drivers include:
The size and shape of your roof
A larger loft needs more flooring, insulation, plasterboard, wiring and finishing materials. Low roof height may also require structural changes, such as lowering the ceiling below or raising the roof.
Structural work
Steel beams, altered rafters and additional supports can make a major difference to the price. Older properties may need more remedial work than a newer house.
Stairs
A permanent staircase is normally required for a habitable room. The location of the stairs affects the design below and may mean moving walls, doors or electrical fittings.
Scaffolding and access
Scaffolding is usually included in a contractor’s overall price, but difficult access can increase the cost. A tall property, narrow passage, restricted parking or a need for extra roof protection may all add time and labour.
Ask whether scaffolding, waste removal, temporary weather protection and site security are included. Do not assume they are.
Your location
Labour and contractor costs are often higher in London and the South East. Transport, parking and restricted access can add further costs in busy urban areas.
A local contractor should be able to explain the regional difference rather than simply adding an unexplained surcharge.
How much does an en-suite add to a loft conversion?
Short answer: An en-suite commonly pushes a loft conversion towards the upper end of its price range. As a broad guide, allow around 10% to 15% extra, although plumbing routes, bathroom size, fittings and drainage can make the increase larger.
For a £50,000 dormer conversion, that could mean roughly £5,000 to £7,500 more.
The extra work may include:
- Hot and cold water supplies
- Waste pipes and drainage
- A shower, toilet and basin
- Waterproofing and tiling
- Ventilation
- Additional electrics
- Heating or towel rails
- Structural work for pipe routes
The position of the existing bathroom can matter. If the new en-suite is close to existing plumbing, the work may be simpler. If waste pipes need to travel across the house, expect more design and labour.
What is usually included in a loft conversion quote?
Short answer: A full quote may include design, structural work, insulation, windows, stairs, electrics, plastering, flooring and standard decoration. However, every contractor defines “finished” differently, so compare the written inclusions line by line before choosing.
A detailed quote may include:
- Site preparation
- Scaffolding
- Structural calculations
- Steelwork and floor strengthening
- Roof windows or dormer construction
- Insulation
- Staircase
- Plumbing and heating
- Electrical wiring and lighting
- Plastering
- Internal doors
- Basic flooring
- Decorating
- Building control inspections
- Waste removal
Common exclusions can include:
- Planning application fees
- Architect or designer fees
- Premium bathroom fittings
- Bespoke storage
- High-end flooring
- Moving existing services
- Repairs to hidden defects
- Extra work caused by asbestos, damp or poor roof condition
Get exclusions in writing. A low headline quote can become expensive if important work has been left out.
Do you need planning permission for a loft conversion?
Short answer: Some loft conversions fall under permitted development, so they may not need a full planning application. The rules depend on the property, roof design, volume limits, location and previous alterations. Mansards and projects in protected areas are more likely to need permission.
According to the Planning Portal’s loft conversion guidance, permitted development limits can include:
- A maximum additional roof volume of 40 cubic metres for terraced houses
- A maximum of 50 cubic metres for other houses
- No extension above the existing roof height
- Restrictions on the front roof slope
- Similar-looking materials
- Limits on balconies and raised platforms
- Specific rules for side-facing windows
Conservation areas, listed buildings and other designated areas may have different restrictions. Previous extensions may also have used part of your permitted development allowance.
Do not rely on a contractor saying “it will be fine”. Ask who will check the planning position and whether a lawful development certificate is appropriate.
Planning permission is also separate from building regulations approval. Your project still needs to meet requirements for structure, fire safety, insulation, stairs and ventilation.
Why is an online loft conversion estimate not enough?
Short answer: Online calculators can provide a rough starting point, but they cannot see your roof structure, access, drainage, planning history or hidden defects. A measured survey and written specification will give you a far more useful basis for comparing quotes.
An online estimate may not know:
- Whether your roof has enough headroom
- How much structural steel is needed
- Where stairs can legally go
- Whether drainage can reach the new bathroom
- Whether the roof needs repairs
- How difficult the site is to access
- Whether planning restrictions apply
- What finish level you expect
Use online ranges to set an initial budget, not to approve the project.
Ask at least two or three suitable contractors for a site visit. Make sure each quote is based on the same drawings and specification. Otherwise, you may be comparing different projects rather than different prices.
What budget should you set aside for a loft conversion?
Short answer: For a basic rooflight conversion, start around £25,000 to £40,000. For a typical dormer with a bedroom and en-suite, allow roughly £48,000 to £65,000. For larger or more complex work, keep £70,000 to £95,000 or more available.
It is sensible to keep a contingency fund of around 10% to 15% for unknowns. Older roofs, hidden damage and changes made during construction can all affect the final bill.
Before work starts, confirm:
- The exact conversion type
- Whether VAT is included
- Whether planning and building control fees are included
- The fixtures and finishes included
- The payment schedule
- The expected completion date
- How variations will be agreed
Do not choose a contractor on price alone. Check relevant experience, insurance, references and how clearly the quote is written.
How can loft conversion specialists win more quote requests?
Short answer: Homeowners often search for prices before they are ready to speak to a builder. Loft conversion specialists who answer cost questions clearly, explain their process and make requesting a quote simple are more likely to earn trust before a competitor gets the enquiry.
A useful service page should explain the conversion types you offer, the areas you cover, likely cost factors and what happens after someone contacts you. Include real project photographs, clear reviews and a straightforward next step.
See the VU1 guide for loft conversion specialists for more on being visible when homeowners search locally.
If your website is not bringing in enough local enquiries, request a VU1 audit. It takes under 15 seconds to request, and the report lands within a few minutes. It checks the practical issues that may be stopping local homeowners from finding or contacting your business.
For £99/month, you can join VU1 membership to monitor your local visibility and make it easier for visitors to take the next step. The aim is straightforward: answer the question early, earn trust and turn more searches into quote requests.
So, what is the honest answer?
Short answer: Budget £35,000 to £80,000 for most UK loft conversions in 2026. A rooflight project may cost less, while a mansard or high-spec conversion may exceed £95,000. Get a survey and detailed quote before committing.
The right figure depends on your house, not an online average.
Use published ranges to understand the market. Then ask a qualified loft conversion specialist to inspect the property, explain the options and provide a written quote that shows exactly what you are paying for.