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Loft Conversion Cost Guide

Loft conversions are a popular method for maximising space and adding value to properties in the UK. We’ve already established the steps involved in loft conversions. In this article, we examine the loft conversion cost in more detail.

Whether you looking for an additional bedroom, a functional home office, or a spacious playroom, a loft conversion can be a cost-effective solution compared to moving house. The process, however, requires careful planning and understanding of potential costs, which can vary widely based on the project’s scale and complexity.

On average, a basic loft conversion for approximately 20 square metres can range between £20,000 and £40,000. More extensive and luxurious conversions may exceed £60,000. To achieve an accurate estimate for your specific project, it’s vital to obtain quotes from multiple contractors and discuss your particular needs and requirements.

Loft conversion cost guide

What is the Cost of a Loft Conversion in the UK?

Loft conversion cost

The cost of a loft conversion varies widely, typically ranging from £20,000 to £60,000 or more. The total expense is influenced by several factors, including your geographical location, the size and type of the conversion, the finishes you select, and the overall complexity of the project.

For a Velux loft conversion, you can expect to pay between £12,000 and £28,000. This type of conversion is generally more affordable due to its simplicity. If you’re considering a conversion with a dormer, the cost increases, falling between £22,000 and £45,000. Dormer conversions add headroom and usable space.

A hip-to-gable conversion, which changes the shape of the roof’s end, usually costs £32,000 to £55,000. This type of project is more extensive and thus more costly. The most expensive option is a Mansard loft conversion. This involves reshaping the entire roof, with prices ranging from £50,000 to £90,000.

Type of conversionAverage cost rangeCost per m²

The above table summarises the costs per square metre for various loft conversion types, helping you to estimate your budget more accurately.

Loft Conversion Cost By Type

Attic or loft conversions come in various types, each offering its own set of benefits and cost considerations. Here, we’ll explore typical costs for different types of attic conversions in the UK, detailing how factors such as finishes, flooring, structural changes, and installations influence the overall expenses.

Velux Conversion

Velux conversions, also known as roof light or skylight conversions, are among the most cost-effective options. This involves adding roof lights or skylights to the existing attic without significant alterations to the roof structure.

Average Cost: £15,000 to £25,000 for a 20 m² area

Factors Influencing Cost:

  • Number of roof lights
  • Insulation
  • Flooring and other features

Dormer Conversion

Dormer conversions extend the existing roof vertically to provide additional headroom and floor space. Popular due to their functionality, they come in various styles such as flat roof, gable-fronted, and hipped roof dormers.

Average Cost: £20,000 to £40,000 for a 20 m² area

Factors Influencing Cost:

  • Type and complexity of dormer
  • Structural alterations

Hip-to-Gable Conversion

In a hip-to-gable conversion, the hip roof is extended to form a gable end, offering more internal space. This type is well-suited for properties with a hipped roof design.

Average Cost: £30,000 to £50,000 for a 20 m² area

Factors Influencing Cost:

  • Extent of structural work
  • Complexity of the project
  • Additional features

Mansard Conversion

Mansard conversions are the most complex and thus, typically the most expensive. They involve changing the roof shape to create a nearly vertical wall, maximising the living space.

Average Cost: £40,000 to £70,000 or more for a 20 m² area

Factors Influencing Cost:

  • Extensive structural alterations
  • Custom design features

Cost Summary Table

Conversion TypeAverage Cost (20 m²)Key Cost Factors
Velux£15,000 – £25,000Number of roof lights, Insulation, Flooring
Dormer£20,000 – £40,000Dormer type, Structural alterations
Hip-to-Gable£30,000 – £50,000Structural work, Project complexity, Features
Mansard£40,000 – £70,000Extensive alterations, Custom design

Each type of attic conversion has its unique benefits and costs. By understanding the different options and their associated expenses, you can make a more informed decision about which type of conversion best suits your property and budget.

Breaking Down Loft Conversion Costs

Velux Loft Conversion (20m²)

Velux conversions are among the more affordable options. You can expect the total cost to range from £15,000 to £25,000. Let’s break down these costs:

  • Architect: Typically charges 7% to 10% of the total cost, amounting to £1,050 to £1,750.
  • Structural Engineer: Fees range from £500 to £1,000.
  • Builders/Contractors: The largest portion of your budget, between £10,000 and £20,000.
  • Plumbers/Electricians: Expect to spend between £1,000 to £2,000.
  • Other Professionals (e.g., Surveyors): Usually cost between £450 to £750.

Dormer Loft Conversion (20m²)

Dormer conversions offer more space and light, with costs from £20,000 to £40,000. Here’s the breakdown:

  • Architect: 7% to 10% of total costs, translating to £1,400 to £2,800.
  • Structural Engineer: £600 to £1,200.
  • Builders/Contractors: Costs range from £12,000 to £24,000.
  • Plumbers/Electricians: Allocate between £1,500 and £3,000.
  • Other Professionals: Fees typically fall between £700 and £1,400.

Hip-to-Gable Loft Conversion (20m²)

Costs for hip-to-gable conversions range from £25,000 to £45,000. Here’s how these expenses break down:

  • Architect: Costs 7% to 10%, so you’re looking at £1,750 to £3,150.
  • Structural Engineer: Fees range between £750 and £1,500.
  • Builders/Contractors: Spend around £15,000 to £27,000.
  • Plumbers/Electricians: £2,000 to £4,000.
  • Other Professionals: £900 to £1,800.

Mansard Loft Conversion (20m²)

For mansard conversions, the more elaborate and expensive option, expect to pay between £40,000 and £70,000:

  • Architect: £1,500 to £3,500.
  • Structural Engineer: £500 to £2,000.
  • Builders/Contractors: Substantial expense here, £20,000 to £40,000.
  • Plumbers/Electricians: £1,500 to £3,500.
  • Other Professionals: £500 to £1,500.

Whether you’re considering a Velux, Dormer, Hip-to-Gable, Mansard, each type has specific costs. Factoring in your budget and the necessary VAT, plumbing, structural work, scaffolding, and potential additional costs will ensure effective planning and execution.

Construction Materials


Proper insulation is crucial for maintaining temperature and energy efficiency in your loft space. Commonly used materials include:

  • Fiberglass
  • Mineral wool
  • Rigid foam boards

The cost of insulation averages between £20 to £50 per square metre. Consider eco-friendly options like recycled fibreglass or natural wool to lower your environmental footprint. Effective insulation can significantly reduce heating and cooling expenses over time.


The pricing of windows depends on their size, materials, and glazing options. Generally, costs range from £300 to £1,500 per window. Energy-efficient windows with double or triple glazing are advisable for superior thermal performance.

Energy-efficient windows not only lower heat loss but also reduce overall energy consumption, leading to decreased carbon emissions and lower utility bills.

Roofing Materials

Typical roofing materials include tiles, slates, and metal:

Material TypeAverage Cost per Square Metre
Tiles£40 – £100
Slates£40 – £100
Metal£40 – £100

For a sustainable option, consider materials like recycled metal or clay tiles. These can offer both environmental and economic benefits by reducing the frequency of repairs and replacements.

Fixtures and Fittings

Fixtures and fittings include elements such as:

  • Lighting fixtures
  • Plumbing fixtures
  • Hardware

Prices range from £500 to £3,000 or more, depending on the brand and quality. Energy-efficient options like LED lighting and low-flow plumbing are recommended for reducing energy and water consumption, which results in long-term cost savings and environmental benefits.

General Building Materials

General building materials include essential components like framing lumber, drywall, and finishes. Costs can vary significantly depending on the chosen quality and quantity, typically ranging from £5,000 to £20,000.

Choosing high-quality, durable and sustainable materials ensures your loft conversion lasts longer, reducing the need for frequent replacements and minimising waste. Additionally, these sustainable options can contribute to a more environmentally friendly project.

How to Reduce Loft Conversion Costs in the UK

Establishing a clear budget for your loft conversion is crucial. Spend time detailing your financial plan and accurately estimate how much you’re willing to spend. If possible, set aside an additional 10% of your budget for unexpected costs.

Choosing the right contractor is important too. Be sure to compare quotes from different professionals and scrutinise their previous work. Talking to previous clients can provide insights, and negotiating prices can help keep costs down. Clear communication regarding costs and expectations will prevent any hidden costs.

Whenever possible, use the existing structure of your home. Major structural changes can increase your budget significantly, so maximising what’s already in place can provide substantial savings.

Efficient space usage contributes to cost savings too. Implementing built-in storage and multifunctional furniture can make the best use of available space.

DIY options can also cut down costs, provided you have the necessary skills and time. Tasks like painting, decorating, or minor carpentry are manageable for many homeowners. Remember, hiring a professional is often the best choice for more complex work to avoid costly mistakes and adhere to building regulations.

Consider a Velux loft conversion, which involves adding roof windows to existing loft spaces. This method is both cost-effective and straightforward, reducing the need for expensive structural changes. Although it offers less additional space, it provides natural light and ventilation, making it an appealing option.

Negotiation with contractors is another valuable strategy. Don’t hesitate to discuss pricing and obtain multiple quotes to find the most affordable and satisfactory proposal. During these negotiations, discuss ways to save money without compromising on quality.

Using reclaimed materials can be a cost-effective and environmentally friendly choice. Materials like reclaimed wood or recycled tiles not only reduce expenses but also lower your project’s environmental impact.

Careful planning is essential. Meticulously organise every detail before beginning construction to ensure efficient use of resources and prevent costly errors. Careful prioritisation helps focus the budget on the aspects that matter most to you, whether that’s adding space, enhancing aesthetics, or boosting functionality.

Each loft conversion project is unique, so tailor these strategies to your specific situation. By planning carefully and making informed decisions, you can achieve a cost-effective and successful loft conversion.

What Affects Loft Conversion Cost In The UK?

The expenses associated with a loft conversion in the UK are influenced by various factors. Understanding these aspects can help you plan and budget effectively.

Roof Type and Structure: The complexity of your roof structure can influence costs. For instance, pitched or hipped roofs are generally easier to convert compared to trussed roofs. Complex structures often need extra support, which can increase overall expenses.

Size and Layout: The loft’s size and how you plan to use the space significantly impact costs. Larger lofts naturally require more materials and labour. Additionally, adding ensuite bathrooms or creating intricate layouts can further raise the price.

Age and Condition of the House: Older homes may need more extensive work to meet current building codes. Issues like damp, rot, or inadequate insulation can increase costs as they need to be addressed during the conversion.

Plumbing and Electrical Needs: Including plumbing fixtures such as bathrooms, or electrical installations like lighting, will impact the budget. Extending plumbing and electrical systems to the loft means more work and higher material costs.

Location: Local regulations and planning requirements vary. Properties in London and the South East often face higher building costs compared to those outside of London. In urban centres, both materials and skilled labour can come at a premium.

Party Wall Agreement: If your property shares a wall with a neighbouring house, such as in terraced or semi-detached homes, a Party Wall Agreement is required. This involves notifying adjoining owners and can incur additional legal and surveying fees, increasing costs.

Quality of Materials and Finishes: The choice of materials and finishes, like flooring, insulation, windows, and fixtures, will affect your budget. High-quality or bespoke materials are more expensive than standard options. For example, opting for luxury vinyl tile for your flooring can range from £10 – £60 per m² flooring for your new loft.

Contractor and Professional Fees: Hiring experienced professionals such as architects, engineers, builders, and tradespeople will add to your costs. Quality workmanship ensures a durable conversion but often comes at a higher price.

The decision to add a loft conversion to a terraced house, semi-detached house, or any other property type has to consider all these variables. Each choice, from the type of roof to the quality of finishes, impacts the final cost.

Additionally, using modular systems or prefabricated shells can sometimes reduce costs and disruption. A well-planned project can add significant value and living space to your home, offering a functional area tailored to your needs.

Get in touch with us

When embarking on a loft conversion in the UK, a variety of professional services are needed to ensure the project’s success. Each service contributes uniquely, addressing specific regulations and technical requirements. The costs of these services can differ widely based on the project’s complexity, size, and location.

To get the best value for your loft conversion project:

  1. Describe your needs
  2. Get free quotes
  3. Choose the best offer

This approach not only optimises your home but also contributes to environmental sustainability.

At Disha Construction, we can help with all types of loft conversions. Simply get in touch with us and we will provide a free custom quotation based on your needs.

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