A Velux loft conversion is one of the most affordable ways to add bright, usable space to your home. This guide breaks down the full cost for 2025, explains how pricing works, and includes our Velux cost calculator so you can get an instant estimate tailored to your loft.
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A Velux loft conversion is one of the most affordable ways to add usable space to your home, and in 2025, most projects fall between £22,000 and £45,000. Smaller, simple roof-light designs sit at the lower end, while larger lofts with insulation upgrades, electrics, and an en suite fall toward the top of the range.
Because Velux loft conversions use the existing roof shape, they avoid major structural work, which helps keep costs down and planning straightforward. In this guide, we break down what you can expect to pay, the factors that push costs up or down, and how to plan your budget with confidence before requesting detailed quotes.
The cost of a Velux loft conversion depends mainly on your loft size, the number of roof windows installed, and the amount of structural work needed. Velux conversions are the most affordable loft type because they retain the existing roof shape, which means fewer materials, shorter build times, and lower labour costs.
In 2025, most Velux conversions fall between £22,000 and £45,000, but smaller lofts with simple layouts can be cheaper. The table below provides a clear breakdown of typical costs by loft size, including structural work, roof windows, electrics, and staircase installation.
This makes it easy to compare your project with national averages before using our Loft Conversion Cost Calculator for a personalised estimate.
Our Velux loft conversion cost calculator gives you an instant estimate based on your loft size, location, and the number of roof windows you want to install. It is designed to help you budget with confidence before speaking to a specialist. Using the calculator is simple:
Enter your loft dimensions, select the Velux windows you prefer, and choose any extra features. You will see a clear price range based on real averages for 2025, giving you a realistic idea of what your project may cost.
*The Velux Loft Conversion Calculator provides cost estimates based on the details you enter, such as loft dimensions, window types, and additional features. These estimates are for guidance only, and actual costs may vary. The calculator is regularly updated to reflect current prices, but ongoing updates ensure the most accurate information. Please request a quote for precise quotes and tailored advice.
As of 2025, a Velux loft conversion can cost anywhere from £22,000 and £45,000, depending on the space size and the features you add. It's widely known for being a cost-effective and relatively straightforward way to transform your loft, a Velux conversion opens up valuable space without significant roof alterations.
Below, we’ve outlined the core costs of a Velux loft conversion, from initial surveys to finishing touches. Remember that these are estimated ranges and may vary based on factors like your loft’s size, the quality of materials, and local labour rates.
*Please note that these loft conversion costs are average estimates and can vary based on factors such as the loft's size, the project's complexity, the quality of materials used, and the region where you live.
A Velux loft conversion is one of the most affordable ways to create extra space, but the final price depends on several factors. Your loft size, the number of Velux windows, structural needs and the location of your property all shape the overall cost. Below, we explain each factor in clear detail so you can understand where your money goes and how to plan your budget with confidence.
The size of your loft has the biggest influence on cost. Larger spaces need more labour, more insulation and more materials, so the total price rises accordingly. Complexity also matters. A straightforward Velux-only conversion may only require reinforcing the floor joists and adding a couple of windows. More involved layouts that include steel beams, an en suite, room partitions or additional structural work will naturally cost more.
Homes with a lower ridge height may require additional work to achieve sufficient headroom. This pushes the build into higher price ranges, while a tall, uncomplicated loft keeps costs at the lower end.
Velux windows vary widely in price, and the number you need will affect your budget. Manual centre-pivot models are the most cost effective, while electric, solar, top-hung and triple-glazed options cost more. Larger formats, combination units and balcony-style Cabrio windows also increase the price.
As a guide, each additional Velux window usually adds between £800 and £1,500, depending on the size, glazing and finish. Homes aiming for maximum natural light should expect costs towards the higher end of this range.
Your interior choices have a significant impact on the total cost. Basic finishes, such as simple flooring and standard plastering, keep spending manageable. Upgrades like engineered timber flooring, bespoke joinery, premium lighting or acoustic plasterboard increase material and labour costs.
Adding a bathroom is the biggest jump. Plumbing, waterproofing, ventilation and waste routing for an en suite typically increase the budget by £5,000 to £12,000.
Every Velux loft conversion must meet Building Regulations, and these checks affect the overall cost of your conversion. Velux loft conversion planning permission usually falls under permitted development, we explore it further.
Most projects pay between £800 and £1,000 for inspections by the local authority or an approved inspector. These cover structure, insulation, fire safety, ventilation and electrical compliance.
Many Velux conversions fall under Permitted Development. You may still need permission if your home is in a conservation area, is a listed building or falls under an Article 4 Direction. A householder planning application usually costs around £206.
Semi-detached and terraced homes often need a Party Wall Agreement. Surveyor fees usually sit between £800 and £1,500. Mid-terrace homes can need agreements on both sides, which increases the cost.
Costs vary across the UK. London, the South East and high-demand areas such as Bristol, Bath, Oxford and Cambridge tend to be the most expensive due to labour rates and material costs. Rural areas can also incur additional travel or access charges.
Our loft conversion cost calculator adjusts your estimate to reflect regional variations.
Difficult access can increase the cost of a Velux conversion. Narrow hallways, restricted entrances, limited space for scaffolding or challenging roof angles can all make the project slower and more labour intensive. Older or uneven roof structures may need extra reinforcement, which adds both time and cost.
Victorian and Edwardian properties are more likely to require additional structural work compared to modern homes.
Architects, structural engineers and surveyors add essential expertise and improve the quality of the build, but their fees contribute to the overall budget. Typical ranges include:
While experienced contractors can cost more, their work tends to be more reliable, reducing the risk of delays or compliance issues.
Hidden problems can emerge during the build. These may include asbestos, rotten timbers, outdated wiring or structural weaknesses. Setting aside a contingency fund of 10 to 15 percent helps cover these surprises without pausing the project.
The length of the build influences what you spend. A typical Velux-only conversion takes three to six weeks. Larger conversions, en suites or upgrades that involve more structural work take longer. Longer timelines increase labour costs and require closer project management.
Managing the project yourself can save money, but it demands time and organisation. Using a professional adds cost but often leads to smoother progress and fewer delays.
As you plan your Velux loft conversion, adding certain features can elevate both the functionality and comfort of your space. While these upgrades can enhance the overall experience, they come with additional costs. Here’s a look at some popular features and what you can expect to invest in each.
Now you understand the cost of additional features to your conversion, it's worth understanding the a couple of things around building your dream conversion. Below we look at consulting your local planning authority, and budgeting for contingencies.
Before starting your conversion, it's natural to have questions, especially regarding costs, below, we've answered the most common queries homeowners ask to help you make confident, informed decisions.
One consideration when trying to understand a Velux loft conversion cost, and justifying that price, is the return on investment you’d achieve in the future, and why.
A Velux can increase the value of your home by around 15 to 25 percent, making it one of the most cost-effective ways to add usable space. Because it relies on rooflight windows rather than major structural changes, it is cheaper to build yet still creates a bright, practical room that appeals to buyers.
This type of conversion is especially attractive because it often falls under permitted development, which keeps the process simpler and quicker. The added natural light, improved energy efficiency and extra floor space make your home more desirable and functional.
For a full breakdown of potential returns and how to maximise your resale value, see our loft conversion roi guide.
A Velux loft conversion costs between £22,000 and £50,000 in the UK. The final price depends on the size of your loft, the number of Velux windows you’re installing, the level of interior finishes, and the location of your property. Smaller lofts can start around £13,000, while larger or more complex projects, which include extras such as an en-suite bathroom, can exceed £40,000.
Yes, we offer an easy-to-use Velux Loft Conversion Cost Calculator right on this page. Simply enter your loft dimensions, select the number and type of Velux windows, and choose any additional features you'd like. You’ll get a tailored cost estimate in under a minute, perfect for early budgeting and planning.
In 2025, the average Velux loft conversion costs between £22,000 and £50,000 in the UK. Smaller, straightforward conversions sit at the lower end of the range, while larger lofts with upgraded windows, better finishes or an en suite fall toward the higher end.
Yes. Our Velux loft conversion cost calculator is designed specifically for UK homes and uses up-to-date regional pricing for labour, materials and Building Control fees. It adjusts for your location, loft size, insulation requirements and window choices to give a realistic estimate tailored to your property.
