Get a detailed breakdown of 2025 loft conversion costs. Compare prices by conversion type, size, and property style, and see what factors can raise or lower your final bill.
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The average loft conversion in 2025 costs between £25,000 and £65,000, depending on the type and complexity of the build. A simple Velux or shell conversion starts from around £25,000, a standard dormer is closer to £50,000, and larger mansard or modular projects can exceed £65,000.
Knowing these ranges upfront helps you budget with confidence and understand where your project is likely to fall before exploring the detailed costs later in this guide.
The type of loft conversion you choose has the most significant impact on price. A simple Velux design costs much less than a full Mansard or modular build, so it is important to compare options before setting a budget.
Below, you’ll find the latest average costs, timescales, and cost per m² for each type of loft conversion in 2025.
*Check out the various types of loft conversion. We have trusted, experienced and verified specialists to provide a detailed quote for you. Look into the specific Velux loft conversion costs, hip to gable loft conversion cost and dormer loft conversion costs guides.
Loft conversion costs typically range from £1,200 to £2,500 per square metre. The price you pay per m² depends on the type of conversion, your home's structure, and the quality of finishes you choose.
Here's a quick breakdown:
Use our loft conversion cost calculator to get a personalised estimate based on your property size and style.
Loft conversion costs vary depending on the size, structure, and location of your home. Some properties are straightforward to convert, while others need extra reinforcement or planning considerations. Below are typical examples by property type to help you set realistic expectations.
Semi-detached homes are popular for loft conversions, often adding a rear dormer to create a spacious bedroom with an en-suite. Structural changes are usually minimal, making this one of the more cost-effective options.
Semi-detached homes with hipped roofs may require a hip-to-gable extension, which increases costs but unlocks more usable space.
Detached loft conversions offer flexibility in design but often need additional steelwork or supports, especially for larger extensions like hip-to-gable or mansard conversions. These projects also have more planning considerations, which can add to the cost.
Detached homes and bungalows allow for larger dormers or even double mansards, but expect higher structural costs.
Victorian and Edwardian terraced houses are well suited to dormer or L-shaped conversions, which maximise the narrow footprint. These layouts can often add a full master suite with a compact bathroom.
Terraced homes usually have tighter access, which can affect scaffolding and labour costs. In London, prices are typically 15–25% higher than the national average.
Maisonette loft conversions often require planning permission and agreement from freeholders or co-owners. When approved, they add valuable living space without increasing the building’s footprint.
Legal considerations such as freeholder consent and Party Wall Agreements can add to the timeline and budget.
Many new build homes have trussed roofs, which need extra reinforcement before conversion. This can make the project more complex and expensive than in older homes, but the result is often a modern, energy-efficient space.
Expect longer build times in trussed-roof properties, as structural work must be carefully designed and approved by building control.
Property type is only part of the equation. Location plays a big role, with loft conversions in London and South East prices are typically 15–25% higher than national averages. This reflects higher labour, material, and scaffolding costs in the region. Detached homes and bungalows give the most creative freedom but usually involve higher structural costs.
Knowing exactly where your loft conversion budget goes helps you plan with confidence. From planning and design to structural work, insulation, plumbing, and final finishes, every stage carries its own costs. This section breaks down the typical expenses so you can see how your budget is allocated and avoid unexpected surprises.
No two loft conversions cost the same. The final price depends on several key factors, from the type of conversion you choose to the materials, labour, and planning requirements.
Structural work, insulation, and finishing touches can all push costs up or down. Understanding what drives the price helps you budget better and avoid unexpected expenses. Let’s break it down.
The more structural changes required, the higher the cost. The cost of a Velux conversion (adding roof windows) is the most budget-friendly.
While a Mansard conversion, which involves rebuilding the roof, is at the top end of the price range. Depending on the size and design, Dormer and Hip to Gable conversions fall somewhere in between.
Takeaway: Simpler loft conversion types like Velux cost less, while Mansard conversions require extensive work and bigger budgets.
A larger loft conversion needs more materials, more labour, and longer build times—all of which increase costs. If your loft layout is unusual or requires multiple levels, expect additional engineering, planning, and construction expenses.
Takeaway: The bigger and more complex the loft, the higher the overall cost due to extra materials and labour.
Your existing roof design significantly affects how expensive your conversion will be. A steep-pitched roof usually has plenty of headroom, making conversion easier and cheaper. Low-pitched or trussed roofs, however, often require structural reinforcements, adding thousands to the cost.
Takeaway: If your loft already has good headroom and support, your costs will be lower. Flat or a truss roof need extra work, increasing the price.
Most loft conversions fall under permitted development, meaning you don’t need planning permission. However, if your project involves significant alterations, is in a conservation area, or exceeds certain size limits, you’ll need planning approval, which adds time and fees to your project.
Takeaway: If your loft conversion sticks to permitted development rules, you’ll avoid extra planning costs.
Your choice of windows, insulation, flooring, and finishes directly impacts costs. Basic uPVC windows are cheaper than bespoke timber options, and premium insulation materials add to the upfront cost but save on energy bills in the long run.
Takeaway: Higher-end materials cost more but last longer and improve your home’s efficiency and value.
Some homes need reinforced joists, steel beams, or adjusted rooflines to support a loft conversion safely. These modifications are essential but can add thousands to the overall budget.
Takeaway: If your loft needs major structural work, be prepared for higher costs and a longer build time.
If your loft is difficult to access, builders may need extra scaffolding, cranes, or specialist equipment, increasing labour costs. Older homes and properties in tight urban spaces can also make construction trickier and more expensive.
Particularly tricky in big cities, the costs of a loft conversion in London can be massively impacted.
Takeaway: The easier your loft is to access, the cheaper and faster the conversion will be.
Experienced loft conversion specialists may charge more upfront, but they help avoid costly mistakes and delays. A cheaper contractor might cut corners, leading to higher costs in the long run for repairs or corrections.
Takeaway: Hiring an experienced professional costs more initially but saves money over time.
Adding triple-glazed windows, better insulation, or solar panels increases initial costs, reduces energy bills, and boosts long-term home value.
Takeaway: Spending more on energy-efficient upgrades can save you money in the long run.
Loft conversion prices fluctuate based on labour demand, material shortages, and economic factors. Booking builders in advance and sourcing materials early can help lower costs.
Takeaway: If possible, plan your loft conversion during a stable market period to avoid price surges.
Loft conversions can boost your home's value and functionality without a hefty price tag. With smart choices and cost-effective strategies, you can achieve your dream loft conversion on a budget.Here are seven ways you can reduce the cost of your dream loft conversion:
Get multiple quotes from different contractors to secure the best price. Comparing quotes can also give you an edge in negotiations, ensuring you get the most cost-effective deal for the same quality of work.
Opt for a simpler conversion like Velux, which does not require significant changes to the roof structure. This can notably reduce both the time and costs involved. Small loft conversions can be the way forward when looking for a simplified design.
You can undertake non-structural work, such as painting, decorating, or fitting finishes. This hands-on approach can lower labour costs, though it demands time and some DIY skills.
Seek opportunities to use reclaimed or second-hand materials, which can be much cheaper than new ones. Salvage yards, online marketplaces, or local building projects clearing out excess supplies can offer quality materials at reduced costs.
Arrange your project during a contractor's off-peak periods, typically in winter or late autumn, when business is slower. During these times, contractors might provide discounts or be more open to negotiating prices.
Enquire with your contractor if there are discounts for buying materials in bulk or through their trade accounts, which often have more favourable rates than retail.
Comprehensive planning before beginning the work can prevent costly modifications and delays during the project. Ensure your design, budget, and agreements with contractors are finalised to avoid unforeseen costs.
You'll also need to consider planning permission and regulations on your windows for your loft conversion too.
Discover loft conversion financing options for your loft conversion today.
A loft conversion is a big investment, and managing your budget properly helps avoid overspending and hidden costs. Careful planning ensures you control your finances while getting the most from your project. Here’s how to budget smartly:
Planning, comparing costs, and preparing for the unexpected will keep your loft conversion on track financially while avoiding budget shocks.
Loft conversions often come with extra costs that aren’t immediately obvious when you start planning. Understanding these hidden expenses can help you budget accurately and avoid any financial surprises.
Here's everything you need to know about loft conversion costs in the UK, answered in our frequently asked questions:
Loft conversions involve making structural changes, installing insulation, updating electrics and plumbing, and adding detailed finishes. All of which require skilled labour and high-quality materials. These combined factors drive up the overall cost.
A Velux (roof light) loft conversion is usually the most affordable option. It requires minimal structural changes and adds light and space without major construction work.
In the UK, loft conversion costs typically range from £1,200 to £2,000 per m², depending on the type of conversion, materials used, and your location.
A well-executed loft conversion can add between 15% and 25% to your home's market value, especially if it creates additional bedrooms or bathrooms.
Labour and material costs differ between regions. Areas like London and the South East often have higher conversion costs due to greater demand for skilled trades and premium finishes.
A loft conversion increases your property's value and saves you the high costs associated with moving house. Many homeowners recoup a significant portion of their investment when selling.
Additional expenses can include party wall agreements, building control fees, structural reinforcements, utility upgrades, interior decoration, and insurance updates.
Yes, a loft conversion is usually cheaper than moving. It avoids costs like stamp duty, legal fees, and moving services, while adding valuable living space and long-term home value.
Most loft conversions fall under permitted development rights and do not require planning permission. However, larger conversions or homes in conservation areas may need formal approval.
