Trimble Architects

Are you asking how much a loft conversion would cost? The price of a loft conversion in the UK typically ranges from £20,000 to £60,000, depending on factors like the size, type of conversion, and materials used. 

This guide breaks down the costs involved, from design and planning to construction and finishing touches. Learn how different types of loft conversions—such as dormer, mansard, and hip-to-gable—affect the overall cost, and get tips on budgeting for your project to maximise both space and value.

How Much Is a Loft Conversion in the UK?

Loft conversions are a great way to add valuable space to your home without the need for moving. But how much would a loft conversion cost in the UK? The average cost of a loft conversion varies depending on the type and size of the conversion. Generally, you can expect to pay between £20,000 and £60,000.

A basic loft conversion, such as a Velux loft conversion, will cost around £21,000 to £28,000. This type of conversion involves adding windows to your existing roof. 

For a dormer loft conversion, which adds a box-shaped structure to make more space, you can expect to pay between £31,000 and £58,000. The most expensive option is the mansard loft conversion, which reshapes the entire roof structure. This can cost from £41,000 to £70,000 and is typically chosen for more complex projects.

Breakdown of Loft Conversion Costs

Understanding the breakdown of loft conversion costs can help you plan your budget more effectively. Here’s what you need to know. Before any work begins, you'll need an initial survey and design, which costs between £300 to £500. An architect or a loft conversion specialist will assess the loft space and create plans for the conversion. This initial step is crucial as it provides a blueprint for the entire project.

Depending on the scale of your project, you might need planning permission. Planning permission fees are around £200 while building regulations approval will cost between £900 and £1,500. This ensures that your loft conversion adheres to legal standards and safety requirements.

Major structural changes such as adding steel beams to support the roof structure can cost between £1,000 and £5,000. This cost will vary depending on the complexity of the work and the condition of your existing structure. Labour costs can take up between 30% to 50% of your total budget. This includes paying builders, electricians, plumbers, and other tradespeople.

Typically, labour costs are around £150 to £200 per day per worker, which can add up quickly depending on the duration of the project. Materials for the loft conversion, including insulation, windows, and flooring, will cost around £10,000 to £15,000. The quality of the materials chosen will greatly influence the total cost. 

For instance, luxury finishes and high-end materials can significantly increase your expenditure. Installing Velux windows costs between £500 and £1,500 per window, while dormer windows can cost significantly more, from £1,200 to £3,000 each. 

The number and type of windows you choose will impact both your budget and the natural light in your new space. Internal finishes such as plastering, decorating, and flooring can add an additional £5,000 to £10,000 to the overall budget. This includes painting, wallpapering, and laying down carpets or other flooring options, which are essential for the final look and feel of your loft conversion.

Adding a new staircase to access the loft space can cost between £1,500 and £3,500. The design and materials used for the staircase will affect the total cost. Electrical work and plumbing will cost around £1,000 to £3,000, depending on your specific requirements.

Different Types of Loft Conversions

Choosing the right type of loft conversion is essential for maximising your space and meeting your needs. Among the different types of loft conversions, each comes with its own benefits and costs. A Velux loft conversion is the most cost-effective option, with prices ranging from £21,000 to £28,000. It involves installing Velux windows into the existing roof structure, requiring less structural work. This type of conversion is ideal if you want to add light and extra living space without significant alterations.

For those needing more space, a dormer loft conversion is a popular choice. This option costs between £31,000 and £58,000. It adds a box-shaped structure to the existing roof, creating additional space and headroom. Dormer loft conversions are versatile and can accommodate various room types, making them a flexible solution for different needs. 

A hip-to-gable loft conversion is another option, costing around £42,000 to £65,000. This type involves altering the hipped roof structure to create a vertical gable wall, thereby increasing the overall space. It is commonly used in semi-detached and detached houses and provides more room compared to some other types of conversions.

Planning Permission for Loft Conversions

Whether you need planning permission for a loft conversion depends on a few factors. Generally, loft conversions fall under permitted development, meaning planning permission is not required as long as the work meets specific criteria. For example, the loft conversion must not exceed 40 cubic metres for terraced houses or 50 cubic metres for detached and semi-detached houses. 

Additionally, no extension is allowed beyond the plane of the existing roof slope of the principal elevation, and no raised platforms, balconies or verandas are permitted. The materials used must be similar to those of the existing house to maintain a uniform appearance.

However, planning permission is required if your conversion exceeds the permitted development criteria or if you live in a conservation area or a listed building. The planning permission application fee is typically £206, but additional costs may be incurred if you need detailed plans or professional advice. 

Regardless of whether planning permission is needed, your loft conversion will need to comply with building regulations. These rules ensure the safety and structural integrity of the conversion. Building regulations approval costs between £900 and £1,500. 

If your property shares a wall with a neighbour, you may also need a Party Wall Agreement. This legal agreement covers construction work affecting a shared wall and typically costs between £700 and £1,000.

Other Costs for Converting a Loft

When planning your loft conversion budget, it is crucial to consider various additional costs that may arise during the project. These expenses will ensure that you have a comprehensive and realistic budget. Firstly, professional fees are an important aspect to consider. Hiring experts such as architects, structural engineers, and project managers can significantly add to your overall expenses. 

These fees can range from £1,000 to £3,000, based on the scope and complexity of your loft conversion. Proper insulation and ventilation are essential for creating a comfortable and energy-efficient loft space. Insulation costs can vary from £500 to £2,500.

Additionally, adequate ventilation is vital to prevent condensation and dampness, which can cost around £300 to £1,000. If you plan to add a bathroom or require additional electrical points, plumbing and electrical work will add to your budget.

Plumbing expenses can range between £1,000 and £3,000, while electrical work may add another £1,000 to £2,000. Finishing touches such as plastering, painting, and decorating can greatly influence the overall appearance of your loft conversion. Decorating costs can range from £1,000 to £5,000, depending on the level of finish you desire. Adding built-in storage solutions can maximise the use of your loft space. 

Costs for built-in storage can vary from £1,000 to £3,000, depending on the complexity and materials used. It is wise to set aside a contingency fund to cover any unexpected expenses or delays that may arise during the project.

A common recommendation is to allocate 10% to 15% of your total budget as a contingency fund. Depending on your home's layout, you may need to move or upgrade existing utilities such as water tanks, boilers, or radiators. These upgrades can cost between £500 and £2,000. 

Site preparation and waste removal are another important consideration. Removing waste generated during construction and preparing the site can add to your budget, with costs ranging from £500 to £1,500. Scaffolding is often necessary for loft conversions, particularly for dormer or mansard types. 

The cost of scaffolding can range from £500 to £2,000, depending on the project's size and complexity. By including these additional expenses in your calculations, you can achieve a more accurate estimate of the total cost of your loft conversion. This comprehensive approach will help you plan your budget effectively and ensure a smoother project execution.

Are you looking for a loft conversion in Richmond or London? Contact us to see how we can help with your loft conversion. Read more by clicking the link below.