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How Much Does a Loft Conversion Cost in the UK?
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Loft Conversion Cost intro
How Much Does a Loft Conversion Cost in the UK?
A loft conversion can be one of the most efficient ways to create additional living space without increasing the footprint of your home.
Depending on the property and roof structure, a loft conversion may create:
- Additional bedroom
- Main bedroom suite
- Ensuite bathroom
- Home office
- Playroom
- Guest room
- Additional storage
For 2026, most UK loft conversions cost approximately £27,500–£75,000+, depending on the type of conversion, structural work, size and specification. A typical project often sits around £50,000.
At Tholos Architects, we help homeowners assess whether the existing roof is suitable for conversion and which type of loft conversion offers the best balance between usable space, planning requirements and budget.
Loft Conversion Cost explained
Typical Loft Conversion Costs in 2026
The type of loft conversion has a major impact on price.
Current UK guidance gives the following broad averages:
| Loft Conversion Type | Typical Cost |
|---|---|
| Rooflight / Velux conversion | £27,500–£30,000+ |
| Dormer loft conversion | Around £50,000 |
| Hip-to-gable conversion | Around £60,000 |
| Mansard loft conversion | £65,000–£70,000 |
| Bungalow loft conversion | Around £75,000 |
| Shell loft conversion | Around £30,000 |
Current 2026 Checkatrade data places most projects between approximately £27,500 and £75,000, while Federation of Master Builders guidance puts rooflight conversions from around £30,000, dormers around £50,000, hip-to-gable conversions around £60,000 and mansards around £70,000.
These are useful budgeting figures rather than fixed quotations.
Loft Conversion Cost per Square Metre
Another way to estimate cost is by floor area.
Current 2026 averages for a typical 30 m² conversion are approximately:
- Rooflight / Velux: £920 per m²
- Dormer: £1,670 per m²
- Hip-to-gable: £2,000 per m²
- Mansard: £2,170 per m²
- Shell conversion: £1,000 per m²
- VAT
- Contingency
These figures vary because each type involves a different amount of structural alteration.
A cost-per-square-metre figure is useful for early budgeting, but it should not be used in isolation.
Why Loft Conversion Costs Vary So Much
Two lofts with the same floor area can cost very different amounts.
One might require:
- Rooflights only
- Minimal structural alteration
- Simple staircase
- Bedroom only
Another may involve:
- Large rear dormer
- Hip-to-gable extension
- New steel structure
- Ensuite bathroom
- Bespoke staircase
- Built-in storage
- Significant roof reconstruction
The amount of work to the existing roof matters just as much as the final floor area.
What Is Included in a Loft Conversion Cost?
A typical loft conversion quotation may include:
- Scaffolding
- Structural floor
- Structural steelwork
- Roof alterations
- Insulation
- Roof covering
- Windows
- Staircase
- Internal partitions
- Electrical work
- Plumbing
- Plastering
- Joinery
- Decoration
For a typical 30 m² dormer conversion, current 2026 cost data shows major elements including scaffolding, structural roof alterations, steelwork, roofing, services, joinery, staircase, plastering and decoration contributing to an overall average around £50,000.
What May Not Be Included?
Depending on the builder and quotation, separate costs may include:
- Architectural fees
- Structural engineer
- Planning application
- Building Control
- Party-wall surveyor
- Bathroom fittings
- Bespoke joinery
- Flooring
- Premium finishes
- Specialist glazing
- VAT
Always check exactly what a quotation includes.
Rooflight Loft Conversion Cost
A rooflight conversion is usually the least expensive type of loft conversion.
It works largely within the existing roof envelope and introduces roof windows rather than substantially changing the roof shape.
Current 2026 guidance suggests approximately:
£27,500–£30,000+
for a typical rooflight or Velux conversion.
It may be suitable where the loft already has:
- Good headroom
- Suitable roof pitch
- Adequate usable floor area
Dormer Loft Conversion Cost
A dormer projects outward from the existing roof and creates additional:
- Headroom
- Floor area
- Full-height wall space
Dormers are among the most common loft-conversion types in the UK.
Current 2026 guidance gives an average cost around:
£50,000
with a broad range of approximately £40,000–£60,000 for a typical 30 m² project.
Hip-to-gable Loft Conversion Cost
Hip-to-gable conversions are often used on:
- Semi-detached houses
- Detached houses
- End-of-terrace properties
The existing sloping hip is extended vertically to create a gable wall.
This increases usable internal volume and is frequently combined with a rear dormer.
Current 2026 guidance gives an average cost around:
£60,000
with typical figures broadly around £50,000–£70,000.
Mansard Loft Conversion Cost
A mansard conversion substantially changes the roof form.
It generally creates:
- Large usable floor area
- Near-vertical rear walls
- Good headroom
- More conventional room proportions
Because of the amount of reconstruction involved, it is normally one of the more expensive types of loft conversion.
Current guidance suggests approximately:
£65,000–£70,000 on average
with a broad range around £50,000–£80,000 depending on the property and specification.
L-shaped Loft Conversion Cost
An L-shaped loft conversion is commonly created on Victorian and Edwardian properties with rear outriggers.
It may combine:
- Main rear dormer
- Smaller dormer over the rear projection
This can create enough additional space for:
- Bedroom
- Bathroom
- Dressing room
- Larger landing
Because of the additional roof structure and junctions, an L-shaped conversion can cost more than a straightforward rear dormer.
Loft Conversion cost
Loft Bedroom and Bathroom Cost
Adding an ensuite or bathroom increases the project cost.
Current Federation of Master Builders guidance suggests a standard loft ensuite may add around:
£3,000–£7,000
depending on specification. FMB
Costs can include:
- Sanitaryware
- Plumbing
- Waste pipe
- Ventilation
- Tiling
- Waterproofing
- Electrical work
- Heating
Loft Conversion Staircase Cost
A permanent staircase is one of the fundamental parts of a proper loft conversion.
Current 2026 cost data gives approximately £2,750 as an average staircase allowance within a typical 30 m² dormer project.
The real cost depends on:
- Width
- Shape
- Position
- Materials
- Balustrade
- Bespoke joinery
The staircase also affects the existing floor below because it requires enough space for safe access.
Stair Position Can Affect the Whole Design
A badly positioned staircase can:
- Waste existing floor area
- Create awkward circulation
- Reduce bedroom size
- Create headroom problems
This is why staircase design should be considered at the beginning of the loft design rather than squeezed in afterwards.
Structural Floor Costs
Existing ceiling joists are not normally designed to act as a habitable floor.
A loft conversion therefore usually requires a new structural floor.
This may involve:
- New timber joists
- Engineered joists
- Steelwork
- Structural decking
The solution depends on the existing building and span.
Structural Steelwork
Steelwork can be one of the largest structural costs.
It may be required to support:
- New floor
- Dormer
- Altered roof
- Existing roof
- Stair opening
Current Checkatrade data allocates around £6,000 to steelwork in a typical £50,000 dormer conversion example.
Complex projects can require substantially more.
Altering the Existing Roof Structure
Traditional and modern roofs behave differently.
The existing structure may contain:
- Rafters
- Purlins
- Struts
- Trussed rafters
Creating usable space can require some existing elements to be altered and replaced with new structural support.
Current 2026 guidance puts roof-structure alterations around £5,000 within a typical dormer conversion cost breakdown
Scaffolding Costs
Loft conversions generally require scaffolding for:
- Roof work
- Dormer construction
- Window installation
- External finishes
Current 2026 data gives an average of around £4,750 for scaffolding on a typical 30 m² dormer project, excluding a temporary roof.
The cost can rise where:
- Access is difficult
- The property is tall
- Scaffolding remains for longer
- Temporary roof protection is required
Temporary Roof Costs
Some loft conversions require a temporary roof to keep the property weatherproof while the existing roof is opened.
This adds cost but can significantly reduce the risk of water damage during construction.
Whether one is required depends on:
- Conversion type
- Programme
- Weather
- Contractor's construction method
Roof Covering Costs
Roof work may involve:
- Removing existing tiles
- Reusing tiles
- New membrane
- New battens
- New tiles
- Leadwork
- Flashings
Current 2026 Checkatrade data allocates around £8,250 to roof coverings within its example 30 m² dormer conversion.
Retiling the Existing Roof
A loft conversion can be a sensible time to consider the condition of the existing roof.
If the roof covering is already approaching the end of its useful life, it may be more efficient to address it while scaffolding is already installed.
Current FMB guidance suggests labour for stripping and retiling can average around £200 per m², with roofing materials additional.
Insulation
A converted loft becomes part of the heated home.
Insulation requirements may affect:
- Sloping roof
- Dormer walls
- Flat roofs
- Floor
- Junctions
Good insulation is important both for regulatory compliance and comfort.
Loft rooms can otherwise become:
- Too hot in summer
- Too cold in winter
Fire Safety Costs
Creating another storey can change the fire-safety requirements for the entire house.
Work may include:
- Protected escape route
- Fire-resistant doors
- Smoke alarms
- Upgraded partitions
- Escape windows where appropriate
Federation of Master Builders guidance notes that loft conversions creating a new storey commonly require a protected escape route and mains-powered interconnected smoke alarms. FMB
These costs should be considered from the beginning.
Loft Conversion Windows
Windows may include:
- Rooflights
- Dormer windows
- Gable windows
- Juliet balcony doors
Costs depend on:
- Size
- Specification
- Material
- Number
- Opening type
Premium glazing can significantly increase the total.
Loft conversion cost
Plumbing Costs
Adding a bathroom may require:
- Hot and cold supplies
- Soil pipe
- Waste pipes
- Pumping arrangements in some cases
- Heating
The location of the bathroom matters.
Positioning it close to existing drainage can sometimes simplify the work.
Electrical Costs
A loft conversion usually requires:
- New lighting
- Sockets
- Smoke alarms
- Bathroom electrics
- Extract ventilation
Current FMB guidance notes that new electrical circuits and testing are a normal part of loft conversion work.
Heating Costs
The new floor may require:
- Radiators
- Underfloor heating
- New heating zone
- Boiler assessment
The existing heating system should be checked to confirm it can support the additional space.
Joinery Costs
Joinery may include:
- Doors
- Skirting
- Architraves
- Staircase
- Storage
- Eaves cupboards
Current 2026 Checkatrade data allows around £4,500 for joinery excluding the staircase in its typical dormer cost breakdown.
Built-in Eaves Storage
The low areas beneath the roof slopes can provide useful storage.
Purpose-built eaves storage can make a loft room much more practical.
It may include:
- Cupboards
- Drawers
- Wardrobes
- Access panels
Bespoke joinery should be budgeted separately where appropriate.
Plastering
New:
- Walls
- Ceilings
- Dormers
- Stairwell
will normally require plasterboard and finishing.
Current Checkatrade data gives approximately £2,750 for plastering in its typical 30 m² dormer example.
Decoration
Decoration may include:
- Walls
- Ceilings
- Doors
- Staircase
- Existing areas affected by construction
Current 2026 guidance gives around £1,750 for decoration within a typical dormer conversion example. Checkatrade
Always check whether decoration is included in the builder’s quotation.
Flooring
Floor coverings may not be included in generic loft conversion prices.
Options include:
- Carpet
- Engineered timber
- Laminate
- Luxury vinyl
The staircase and landing may also need new finishes.
loft conversion cost
Loft Conversion Cost in a Terraced House
Terraced properties commonly use rear dormer conversions.
A typical cost is around:
£50,000
according to current 2026 UK guidance. Checkatrade
Access can affect the price where materials and waste need to pass through the house.
Loft Conversion Cost in a Semi-detached House
Semi-detached houses can often accommodate:
- Rooflight conversions
- Rear dormers
- Hip-to-gable conversions
Current 2026 guidance places typical semi-detached loft conversion costs around £50,000, depending on type and specification.
Loft Conversion Cost in a Detached House
Detached properties may offer greater design flexibility.
The project might combine:
- Hip-to-gable
- Dormer
- Rooflights
- Gable windows
Current UK guidance gives around £62,500 as a typical figure for detached-house loft conversions.
Bungalow Loft Conversion Cost
Bungalows can have large roof footprints and therefore considerable conversion potential.
Current 2026 guidance gives approximately:
£62,500–£87,500
for a typical 50 m² bungalow loft conversion, with an average around £75,000. Checkatrade
The larger floor area can make the overall project more expensive even where the structure is relatively straightforward.
Shell Loft Conversion Cost
A shell conversion generally completes the major structural work while leaving some internal finishing to the homeowner.
It may include:
- Structural floor
- Roof alteration
- Dormer
- Windows
- Basic weatherproofing
Current guidance puts a typical shell conversion around:
£22,500–£37,500
with an average around £30,000. Checkatrade
This can reduce the initial contractor cost, but the remaining work still needs to be budgeted.
Planning Permission
Many loft conversions can fall within permitted development rights.
However, planning permission may be required where the proposal:
- Exceeds permitted-development limits
- Raises the ridge
- Significantly alters the roof
- Involves certain protected properties
- Is located in an area with additional restrictions
Mansard conversions are particularly likely to require planning permission because of the scale of roof alteration.
Loft Conversions in Conservation Areas
Loft conversions in conservation areas may face tighter design controls.
Considerations can include:
- Roof form
- Dormer size
- Visibility
- Materials
- Rooflights
Building Regulations
Loft conversions generally need to comply with applicable Building Regulations.
These may cover:
- Structure
- Fire safety
- Stairs
- Insulation
- Ventilation
- Electrical work
- Drainage
Current cost guidance confirms Building Regulations are a normal compliance requirement for loft conversions.
Structural Engineer Costs
Structural engineering may be required to design:
- New floor
- Steel beams
- Dormer support
- Roof alterations
- Stair opening
The fee depends on the complexity of the project.
Party Wall Costs
Loft conversions can sometimes affect party structures.
This can be relevant where steel beams or other structural work interact with shared walls.
Depending on the work, the Party Wall etc. Act 1996 may apply.
Any potential surveyor fees should be included in the overall project budget.
Professional Fees
In addition to construction, the budget may need to include:
- Architectural services
- Structural engineer
- Planning
- Building Control
- Party-wall surveyor
- Other specialist consultants
These costs may not be included in headline builder prices.
These costs may not be included in headline builder prices.
Always check whether VAT is included in:
- Builder quotations
- Published cost guides
- Specialist supplier prices
A figure excluding VAT can appear considerably lower than the actual project cost.
Contingency
A loft conversion involves opening and altering an existing roof.
That means some conditions may not become completely clear until work starts.
Federation of Master Builders recommends keeping around a 10% contingency fund for unexpected loft-conversion costs. FMB
For an older or more complicated property, a larger allowance may be sensible.
loft conversion cost
Can I Do a Loft Conversion for £30,000?
Possibly.
Around £30,000 is currently realistic for:
- Straightforward rooflight conversion
- Shell conversion
- Relatively simple small project
Current 2026 guidance puts Velux conversions around £27,500–£30,000 and shell conversions around £30,000.
A full dormer with bathroom and high specification is unlikely to fit comfortably within the same budget.
Can I Do a Loft Conversion for £50,000?
Yes.
Around £50,000 is currently a typical figure for a standard dormer conversion.
What is achievable depends on:
- Size
- Location
- Structure
- Bathroom
- Specification
Can I Do a Loft Conversion for £60,000?
A £60,000 budget can provide more flexibility.
It may support:
- Larger dormer
- Hip-to-gable conversion
- Ensuite
- Better finishes
Current guidance places hip-to-gable conversions around £60,000 on average.
Can I Do a Loft Conversion for £75,000?
A £75,000 budget can support a substantial conversion in many parts of the UK.
Depending on the property, this might include:
- Mansard conversion
- Large hip-to-gable and dormer combination
- Bungalow conversion
- Higher specification bedroom suite
Can a Loft Conversion Cost £100,000?
Yes.
Larger or premium projects can exceed £100,000, particularly where they involve:
- Major roof reconstruction
- Bespoke glazing
- Multiple bathrooms
- High-end joinery
- Complex structure
- London labour rates
The headline national averages should therefore not be treated as maximum prices.
loft conversion Cost
How to Reduce Loft Conversion Costs
The best way to control cost is to select the right type of conversion for the existing roof.
Possible savings include:
- Retain existing roof form where possible
- Use rooflights rather than unnecessary dormers
- Keep structural work simple
- Position bathroom near existing drainage
- Use standard windows
- Avoid excessive bespoke joinery
- Keep specification realistic
Do Not Create More Roof Space Than You Need
The most expensive option is not automatically the best.
A large mansard may create maximum floor area, but a smaller dormer might already provide everything the household needs.
The design should respond to:
- Required rooms
- Headroom
- Storage
- Staircase
- Budget
rather than simply trying to maximise volume.
Plan the Staircase Early
A well-positioned staircase can improve:
- Loft layout
- Existing first floor
- Headroom
- Circulation
A poor staircase arrangement can force expensive redesign later.
Position Bathrooms Carefully
Keeping a new bathroom relatively close to existing:
- Soil stack
- Plumbing
- Services
can simplify construction.
That does not mean the bathroom must sit directly above the existing bathroom, but service routes should be considered during design.
loft conversion cost
Get Comparable Builder Quotes
When the design and technical information are sufficiently developed, builders should ideally price the same scope.
This helps you compare:
- Structure
- Roofing
- Staircase
- Services
- Finishes
- Exclusions
Loft Conversion Budget Checklist
Your complete budget may need to include:
- Scaffolding
- Structural floor
- Steelwork
- Roof alterations
- Roof covering
- Dormer
- Rooflights
- Staircase
- Insulation
- Fire-safety work
- Electrical work
- Plumbing
- Heating
- Bathroom
- Joinery
- Flooring
- Decoration
- Architectural fees
- Structural engineer
- Planning
- Building Control
- Party-wall costs
- VAT
- Contingency
Do not assume the builder’s headline figure represents every cost needed to create the finished room.
How Tholos Can Help Control Loft Conversion Costs
The cost of a loft conversion is heavily influenced by early design decisions.
At Tholos Architects, we can consider:
- Existing roof structure
- Headroom
- Staircase
- Conversion type
- Structural strategy
- Bathroom position
- Natural light
- Planning constraints
- Budget
together from the beginning.
The aim is to create the space you actually need without introducing unnecessary structural work or roof alterations.
Client experience
"
Lorem ipsum dolor sit amet, consectetur adipiscing elit. We had a vision for our home but no idea how to realise it. Tholos Interiors took complete ownership of the project — every detail was considered, every decision explained. The result exceeded everything we had imagined.
– Lawrence Ipsum, Homeowner · London –
Frequently Asked Questions
How much does a loft conversion cost in the UK?
Most UK loft conversions currently cost approximately £27,500–£75,000+, depending on the type, size, structure and specification
What is the average loft conversion cost?
Around £50,000 is a useful current benchmark for a typical loft conversion, particularly a standard dormer.
How much does a dormer loft conversion cost?
A typical dormer costs around £50,000, with current guidance giving approximately £40,000–£60,000 for a 30 m² conversion.
How much does a hip-to-gable loft conversion cost?
Current 2026 guidance gives an average around £60,000.
How much does a mansard conversion cost?
Current guidance places a typical mansard around £65,000–£70,000, with larger or more complex projects potentially costing more.
What is the cheapest type of loft conversion?
A rooflight or Velux conversion is generally the least expensive because it involves the least alteration to the existing roof.
Does a loft conversion need planning permission?
Not always.
Many conversions may fall within permitted development rights, but planning permission may be required depending on the scale, roof alterations, location and property.
Choose the Right Conversion Before You Set the Budget
The cost of a loft conversion depends heavily on how much the existing roof needs to change.
A simple rooflight conversion may start around:
£27,500–£30,000
while dormers typically sit around:
£50,000
and more substantial hip-to-gable or mansard conversions commonly reach:
£60,000–£70,000+.
The best option is not necessarily the largest conversion.
It is the one that creates the space you need while working sensibly with the existing house, planning constraints and available budget.
At Tholos Architects, we can help identify that option before construction costs become fixed.
Disclaimer
This article is part of a series created by our dynamic marketing team for informational purposes only. While we strive to review all content thoroughly, occasional oversights may occur, even after publication. Therefore, we cannot accept liability for any interpretations or use of the information provided. For the most up-to-date information or to report any discrepancies, please contact us at hello@tholos-architects.com.
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