How Much Does a Loft Conversion Cost in 2025?
Pulling off a loft conversion can be a tricky prospect, especially when you have a defined budget. In this guide, discover the cost of all common types of loft conversions, including a detailed breakdown of pricing and the factors that affect them.
Loft conversions are one of the most efficient ways to add space to your existing house. But without meticulous planning and preparation, a dormer loft conversion can surely give headaches, especially during budgeting.
What is the Average Loft Conversion Cost in 2025?
An average loft conversion project in the UK will cost you between £25,000 and £65,000. While there are numerous factors that decide the cost variation, one primary factor is the type of loft conversion.
For example, if you are planning a shell loft conversion, the cost may start from as low as £10,500 for a basic conversion. This is because a shell loft conversion is not your typical full conversion and focuses only on building the structural framework. The conversion is without internal finishes like plastering or flooring and is limited to creating openings for windows & doors, adding reinforcements for floors, walls, and the roof, and building the staircase.
Whereas, if you are planning for a full-fledged loft conversion, such as a velux conversion, a dormer conversion, or a mansard conversion, loft conversion cost will usually range between £25,000 and £65,000. Read more about the mansard vs dormer loft conversion
While this not a set range, the cost of a loft conversion can vary based on various factors. At Extension Architecture, we are specialists in loft conversion projects, from planning, quotation, designing, and building. If you are looking for an accurate quote, consult our experts and avail yourself of a free quote for your project.
Factors that Affect Loft Conversion Cost
As is the case with many construction projects, loft conversion cost is usually influenced by numerous factors. Listed below are some of the important ones –
Type of Conversion: Whether it is a shell conversion or a full-fledged conversion such as a velux, mansard, hip-to-gable, or a dormer, here is where the cost significantly varies.
Size of the Loft Space: The larger the conversion area, the higher the cost due to additional materials and labour.
Design Complexity: If the layout is complex to convert and involves multiple living spaces, rooms, and windows, the cost will increase.
Additional Features: If your loft conversion plan involves adding rooflights, underfloor heating, or solar panels on the roof.
Type of Staircase: The type of stairs is an important factor that affects the cost of loft conversion. From custom, spiral, or bespoke space-saving designs, loft conversion costs are bound to vary.
Structural Strength: If your loft space lacks structural stability, adding reinforcements might be necessary to strengthen the structure, and this will incur additional costs.
Building Regulations: Complying with building regulations is a mandate for all construction projects, including loft conversion. For example, the cost to add fire safety systems, insulation, or other compliances will add to the cost of building regulations.
Accessibility: Accessing the attic space may be a challenge depending upon the existing structure. By means of scaffolding, which will add to the cost, roofs can be accessed to continue with the conversion.
Other factors, such as a freeholder agreement in case the loft space is not owned by you, or a party wall agreement if there is a need to hire a surveyor, may add to the expense.
Cost of Loft Conversion
Now that we have understood the factors that contribute to the variation in costs, let’s dive straight into the cost of loft conversion in the UK.
In this guide, we will be classifying loft conversion cost based on the type and area of loft conversion. The numbers mentioned below are ballpark figures. If you require an accurate quotation, get in touch with our experts.
Cost of Loft Conversion by Type and Order of Popularity –
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Cost of Loft Conversion by Area
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Loft Conversion Cost by Types
While cost is certainly a factor that plays a critical role in deciding on the project, what’s more important is the suitability. If you are planning a loft conversion, you should know which type of conversion suits you better and why.
Below are characteristics of some of the common types of loft conversions in the UK.
1. Dormer Loft Conversion Cost
Cost range – £45,000 to £65,000.
A dormer loft conversion is characterised by creating a vertical wall and a flat roof on top. This creates a box-like structure that projects vertically from the sloping roof. The roof is extended outwards to create more headroom space.
- Dormer loft conversions often require planning permission and depends on the location and scale of the project.
- Suitable for semi-detached, detached, and terraced properties.
- Dormer loft conversions may take 4-6 weeks to complete.
Hip-to-gable Loft Conversion Cost
Cost range – £40,000 to £70,000
A hip-to-gable conversion converts a sloped roof (hip) into a vertical wall (gable). By doing this, the height of the roofline is increased, and the loft gains more headroom space and usable area.
This type of conversion requires the removal of the existing sloped roof section and construction of a new vertical wall and is an ideal choice for those with an expanding family tree.
- While some sections of hip-to-gable loft conversion require planning permission, some may not. It’s always advised to verify with planning authorities.
- Generally, a hip-to-gable loft conversion can add significant value to your property and is suitable for detached, semi-detached, and end-of-terrace properties. These properties usually have hipped roofs.
- Hip-to-gable loft conversions usually take 5-7 weeks to complete.
Velux Loft Conversion Cost
Cost range – £25,000 to £32,000
Velux loft conversions are one of the easier of all loft conversions when it comes to execution. They are characterised by adding velux windows to the existing roof that enhances the airiness and natural light penetration inside the loft space. This type of loft conversion warrants negligible structural changes, thus making it a cost-effective option.
- Planning permission is usually not required for velux loft conversion unless the property is in a listed area or in a conservation area. However, there are limits to height and width that should not be exceeded beyond permitted development limits.
- Any property with a sloping roof can be ideal for a velux loft conversion.
- A velux loft conversion can be completed in 4-6 weeks.
Mansard Loft Conversion
Cost range – £50,000 to £75,000
Mansard loft conversions warrant major renovation works and hence are relatively expensive when compared to other loft conversions. They are characterised by removing the entire roof structure and adding a new storey on top.
This allows for greater headroom space, which can accommodate large windows and results in creation of spacious living areas.
- As mansard loft conversions require significant structural alterations, most of the cases require planning permission.
- Suitable for semi-detached, detached, terraced properties, and bungalows.
- A mansard loft conversion can be completed in 8-10 weeks.
Loft Conversion Cost per square metre
Using a per square metre cost allows for a standardised metric for estimating material and labour costs, which helps in informed decision-making. From a budgeting point of view, homeowners can plan for realistic budgets and can closely track their project’s progress as they have the advantage of being able to anticipate and estimate costs in a comprehensive way.
- Dormer Loft Conversion Cost: £1,500 to £2,000 per sq metre
- Hip-to-gable Loft Conversion Cost: £1,800 to £2,200 per sq metre
- Velux Loft Conversion Cost: £1,100 to £1,600 per sq metre
- Mansard Loft Conversion Cost: £1,900 to £2,600 per sq metre
Additional Costs that are Part of a Loft Conversion Project
Executing a loft conversion involves many miscellaneous works before and after the conversion. While some of them are directly related to construction, some include professional and miscellaneous costs –
Professional Costs
- Fee for Architects & Structural Engineers: £500 to £1,500
- Planning Permission Fees: £230 to £250
- Building Regulations Fees: £250 to £350
- Party Wall Survey Costs (If your loft conversion involves a shared wall)
Other Construction Costs
1. Staircase Costs
- £1,000 to £2,000 for basic straight-running stairs
- £5000 to £7,500 for bespoke stairs
- £4000 to £5,500 for spiral stairs
- Space-saving designs can range between £1,250 and £3,500
2. Roof Joists: £450 to £900
3. Scaffolding: £4,500
4. Cladding: £2,000 to £6,000, depending on the type of material (uPVC, Timber, Aluminium)
5. Underfloor Heating: £30 to £100 per square metre
6. Bat Survey: £250 to £1000
7. New Boiler: £1,000 to £3,500, depending on the type of boiler
8. Plumbing & Electrical Installation Cost: £3,000
9. Insulation Costs
Labour Costs
Labour costs, which are inclusive of the average total cost, vary differently for different loft conversion types –
Dormer Loft Conversion: £17,000 to £25,000
Hip-to-gable Loft Conversion: £20,000 to £30,000
Velux Loft Conversion: £8,500 to £12,500
Mansard Loft Conversion: £15,000 to £35,000
One of the important factors that make up the labour costs is the cost that goes into remunerating the tradespeople.
Mason: £22 to £35 per hour
Plumber: £30 to £40 per hour
Electrician: £40 to £100 per hour
Renderer: £28 to £45 per hour
Tiler: £18 to £35 per hour
Conclusion
Costs are a critical part of a loft conversion project. They can spiral up in no time if not planned well. Hiring loft conversion specialists will help you reduce significant costs during the construction of the project. This is because architects and professionals usually deploy project management techniques that involve optimal resource use and eliminate third parties like vendors. This helps in significant cost reduction whilst ensuring a highly efficient & successful completion.
With years of experience and a strong reputation in delivering high quality & successful loft conversion projects, Extension Architecture can handle everything from ideation, conception, and planning to building the project by leveraging our project management expertise.
Contact us today!
