If you are you trying to figure out what a loft conversion actually costs in the UK right now then you have probably already hit the same wall as everyone does: one website quotes £20k, another says £80k and you are left no closer to knowing what your own project might cost.
Here is the honest answer: in 2026, you are looking at anywhere from about £22,000 for a straightforward Velux conversion to £95,000 for a full mansard. That is not a vague estimate designed to cover ourselves, it's a genuinely huge range. A Velux conversion and a mansard are basically different builds with wildly different amounts of structural work involved. Before you start asking round for quotes, it is worth understanding which type actually fits your property and what are the overall costs involved.
The figures on this page come from real quote requests submitted by homeowners through our platform and are cross referenced with current Q2 2026 market pricing from vetted specialists working across 519 UK towns and cities. We update these numbers regularly so what you are seeing here reflects what homeowners are actually paying right now, not outdated estimates or industry guesswork.
Loft Conversion Cost UK 2026: Quick Overview
Below is a summary of average loft conversion costs across the UK in 2026, broken down by conversion type. These figures cover structural steelwork, insulation, windows, plastering, electrics and a basic staircase. An en-suite bathroom is not included unless stated otherwise.
| Conversion Type | UK Average Cost | London and South East | Usable Space |
|---|---|---|---|
| Velux / Rooflight | £22,000 to £45,000 | £28,000 to £55,000 | 15 to 30m² |
| Dormer | £45,000 to £65,000 | £52,000 to £80,000 | 25 to 40m² |
| L-Shaped Dormer | £55,000 to £75,000 | £65,000 to £97,500 | 30 to 50m² |
| Hip to Gable | £45,000 to £75,000 | £55,000 to £90,000 | 25 to 45m² |
| Hip to Gable with Rear Dormer | £60,000 to £85,000 | £75,000 to £105,000 | 35 to 50m² |
| Mansard | £55,000 to £95,000 | £65,000 to £120,000 | 35 to 55m² |
| Bungalow Loft Conversion | £55,000 to £90,000 | £65,000 to £110,000 | 30 to 50m² |
London and the South East are usually 20 to 30 percent higher than the national average, mainly down to higher labour rates and material costs. The Midlands and the North of England generally come in 15 to 20 percent below the figures shown above.
Loft Conversion Cost Calculator
If you are not sure what your specific project might cost then use our free loft conversion cost calculator to get an instant estimate based on your conversion type, property type and location. Just select your options below and the calculator will give you a realistic price range based on current 2026 market data.
Please note that this estimate is just a starting point based on average pricing across the UK and your actual quote will depend on the specific details of your property, the condition of your existing roof structure and your chosen specification. Once you have your estimate use the button below to request free detailed quotes from vetted local specialists who can give you an accurate figure based on a survey of your actual property.
Please note that these calculations are just a ballpark figure and the only way you can get an exact calculation is by requesting a quote and getting a survey done by your chosen conversion contractor.
Loft Conversion Cost by Type: Detailed Breakdown
The type of conversion you choose is the single biggest factor in determining your loft conversion cost. Here's a detailed breakdown of what each type costs and why their prices differ so much.
Velux Loft Conversion Cost
A Velux (or rooflight) conversion is the cheapest option out there, mainly because there is barely any structural work involved. The roof stays the shape it already is and windows go straight into the slope and that's more or less it. No building out the roofline, no new walls and that is why the price stays down.
Right now in 2026, you are looking at £22,000 to £45,000 for one of these across the UK. What pushes the number up or down is the size of the loft, how many windows you want, what quality they are and how nice a finish you are going for. A small loft with a plain finish sits near £22k while a bigger space with good windows and a proper finish can move up to £45k.
The downside to a Velux conversion is the headroom. Since the roof shape doesn't move, you only get full standing height in the middle of the room right under the ridge. So this only really makes sense if your loft already has decent height to work with ideally at least 2.2 metres at the ridge.
Full Velux loft conversion guide →Dormer Loft Conversion Cost
The dormer is the one most people go for and it sits right in the middle price-wise. You are pushing part of the roof outward to create actual vertical walls and a flat or low pitched section on top which gives you full standing height across most of the floor. Because you get more space out of this conversion, it is more preferable by homeowners.
A standard rear dormer can cost you roughly £45,000 to £65,000 across the UK. If you decide to go for an L-shaped one, this can cost you between £55,000 to £75,000. Add 20% to 30 on top if you're in London or the South East. If you want an en-suite in there too then that's another £8,000 to £15,000 on top of your actual cost.
Since we are talking about costs, you usually don't need a planning permission as they fall under permitted development rights which means you can save both money and time.
Full dormer loft conversion guide →Hip to Gable Loft Conversion Cost
Talking about costs, a hip to gable on its own can cost you between £45,000 to £75,000 in 2026 if you are just replacing the sloped end with a vertical gable wall and adding Velux windows. But nobody actually stops there and almost everyone pairs it with a rear dormer because that is where the real space comes from as the gable alone doesn't get you much extra floor area on its own. If you decide to go with this combination, you're looking at £60,000 to £85,000.
One factor that affects the cost is location so If you are in London or the South East, these costs will rise by up to 20%.
Full hip to gable loft conversion guide →Mansard Loft Conversion Cost
A mansard will cost you £55,000 to £95,000 and that's the highest price bracket out of all the conversion types because the whole back of your roof gets rebuilt and not just extended or dressed up.
If you are in London or South East region then the costs can easily exceed £100,000 or even more for larger or more complex conversions.
Unlike other conversion types a mansard requires full planning permission which adds time and cost to the project. Also party wall agreements with adjoining neighbours are also typically required on terraced and semi detached properties so make sure to add fees of £800 to £1,500 per neighbour.
Full mansard loft conversion guide →Loft Conversion Cost Per Square Metre 2026
You can also work this out per square metre which tends to be a clearer way to compare across all conversion types rather than just looking at the total price.
| Conversion Type | Build Cost Per m² | Total Project Per m² |
|---|---|---|
| Velux | £800 to £1,500 | £1,000 to £1,800 |
| Dormer | £1,200 to £2,000 | £1,400 to £2,500 |
| Hip to Gable | £1,500 to £2,200 | £1,800 to £2,800 |
| Mansard | £1,700 to £2,500 | £2,000 to £3,000 |
Build costs and project costs are two different things as the build cost per m² alone covers the structural work, insulation, windows and basic finishes. On the other hand total project cost per m² includes professional fees, building regulations, the staircase and finishing work. Please keep in mind that a bathroom addition is not included in either figure so you should budget separately for that at £8,000 to £15,000 depending on specification.
Loft Conversion Cost by Property Type
The type of your property ultimately dictates the costs of conversion as you have to factor in things like the roof span, structural complexity and what attic conversion types are available to you house. Here are the average costs:
| Property Type | Typical Cost Range 2026 | Most Common Conversion |
|---|---|---|
| Terraced house | £45,000 to £75,000 | Rear dormer or mansard |
| Semi detached house | £45,000 to £80,000 | Dormer or hip to gable with dormer |
| Detached house | £50,000 to £90,000 | Dormer or hip to gable |
| End of terrace | £45,000 to £80,000 | Hip to gable with rear dormer |
| Bungalow | £55,000 to £90,000 | Full bungalow loft conversion |
As you can tell from the table, bungalows usually cost more to convert than other property types because the roof span is wider and you need bigger beams, more steel, and higher structural engineer fees. Many bunglows have trussed rafter roofs which adds even more complexity to the job and the overall costs increase.
Loft Conversion Cost by Location
Where you are in the country changes the price more than most people expect as factors like day rates for builders, what subcontractors charge or even getting materials delivered, none of it costs the same from one region to the next.
| Region | Standard Dormer Cost | vs National Average |
|---|---|---|
| London Central | £65,000 to £95,000 | 25 to 40% above average |
| London Outer and South East | £55,000 to £80,000 | 15 to 25% above average |
| South West | £48,000 to £68,000 | Around average |
| Midlands | £43,500 to £63,000 | 5 to 10% below average |
| North West and North East | £37,500 to £57,000 | 15 to 20% below average |
| Scotland | £39,000 to £57,000 | 10 to 15% below average |
| Wales | £40,000 to £60,000 | Around to slightly below average |
Please note that these regional figures are based on a standard rear dormer conversion and can be used as the reference point for other types of conversions that are you interested in.
What You Are Actually Paying For
Beyond conversion type and location, you should also look at a few other things that can move your cost up or down and knowing what they are makes it easier to calculate the actual costs and compare quotes from contractors.
Roof Structure
This is one of the biggest cost factors and most people don't know about it until they get a full inspection done by a specialist. Older properties that are generally from the pre-1960s, they have traditional cut roofs which are easier to modify. But almost all newer properties often have trussed rafter roofs so the contractor has to remove and replace every truss to carry out the conversion work. That adds a lot of cost and steelwork and can push the final price of conversion above the averages mentioned earlier.
Structural Steelwork
Every loft conversion needs steel beams to carry the weight of the newly added floor and roof. Steel alone costs £1,500 to £5,000 and you have to pay for other services separately including installation, padstones and a building control inspection fee. Bigger jobs like hip to gable and mansard need more steel than a simple Velux or rear dormer.
Adding a Bathroom
Most people who specifically convert their loft into a bedroom want an en-suite too. If you decide to do a standard one, the additional costs will range between £8,000 to £12,000 but if go with the premium finishing, costs can rise upto £15,000 or more.
Staircase
As per the building regulations, you are required to have a fixed staircase for any habitable loft conversion. A straight staircase in a straightforward spot usually costs £2,000 to £4,000 installed but if you need a winder staircase or one that needs altering the layout of the floor below, the costs can increase up to £4,000 to £8,000.
Insulation Specification
Building regulations set minimum thermal standards for loft conversions under Part L of The Building Regulations 2010. If you have an older property then the rafters might not be deep enough to meet those standards and you will have to get over-rafter insulation done or do a warm roof build. This is costly but it makes your house more energy efficient so it can save you money long term.
Finish Specification
Basic and high-spec finishes cost very different amounts. Standard windows and flooring versus bespoke joinery and premium fixtures makes a real difference to the final cost. You should always decide your finishing specifications before getting quotes so can compare like for like.
Hidden and Additional Loft Conversion Costs
A common frustration while receiving loft conversion quotes is finding out that the costs you assumed were included actually are not included by the contractors. Here is a full list of extras to budget for things that often get left out of the main price.
These extras can easily add £5,000 to £10,000 on top of the headline quote. You should always ask each specialist to confirm in writing about what is included in the quotation and work.
Does a Loft Conversion Add Value to Your Home?
Yes and it can be often more than you would actually expect. As per the research by Nationwide Building Society, if you add a double bedroom and bathroom to your loft, this can boost your home's value by up to 21%. In London and the South East, these numbers can be even more.
| Conversion Type | Typical Value Added | Approximate ROI |
|---|---|---|
| Velux | 10 to 20% | 60 to 75% |
| Dormer | 15 to 25% | 65 to 75% |
| Hip to Gable with Dormer | 15 to 25% | 60 to 70% |
| Mansard | 20 to 30% | 65 to 75% |
How to Reduce Your Loft Conversion Cost
There are actually several ways that can help you properly budget your conversion project without compromising the overall comfort, quality and safety.
Get at Least 3 Quotes
Getting more than one quote is the best way to make sure that you are not overpaying for the conversion job. For the exact same job, the highest and lowest quotes from different specialists can differ by £5,000 to £10,000. Comparing a few quotes side by side also helps you spot what is included and what is not.
Choose the Right Conversion Type for Your Property
If your loft already has good head height of 2.2 metres or more a Velux conversion may create all the space you need at a fraction of the cost of a dormer. Make sure not to choose a complex conversion type if a simple one can do the job perfectly for you.
Do Not Add a Bathroom as an Afterthought
If you want a bathroom, make sure to plan for it from the start because if you decide to add one after the build is done, the whole process will cost you way more than doing it the first time.
Combine with Planned Maintenance
If your roof needs repairs or you are planning to rewire the property combining these with a loft conversion can save money on scaffolding costs which would otherwise be needed separately for each project.
Consider a Shell Conversion
A shell conversion involves getting a specialist to complete all the structural work including floor, walls, windows and staircase and then managing the internal fit out yourself or through separate trades. This can reduce the overall cost but requires more time and project management from you.
Decide Your Specification Early
Changing your mind about your design and build specs during the job will cost you a ton. Sort out your windows, flooring, bathroom and storage specifications before the build begins because decisions made on site always cost more than the same ones made on paper.
Frequently Asked Questions
How much does a loft conversion cost in the UK in 2026?
The cost of loft conversion depends on the type and specifications you choose and it can usually range between £22,000 for a basic Velux conversion up to £95,000 or more for a full mansard build. The most common type is a rear dormer and it's cost is in between £45,000 and £65,000 across the UK. These costs increase by 20% to 30% if you live in London or South East region.
What is the cheapest type of loft conversion?
A Velux or rooflight conversion is the cheapest at £22,000 to £45,000 and you will get less usable space after conversion if you choose this type.
How much does a loft conversion cost in London?
Loft conversion costs in London are 20 to 40 percent higher than the national average. For reference, a standard rear dormer costs between £55,000 to £95,000. If you are in central London and you decide to go with a premium finish, this can go past £100,000.
How accurate is a loft conversion cost calculator?
A cost calculator gives you a useful estimate based on your conversion type, property and location which is a good starting point for budgeting. But it cannot see your actual roof, head height or any hidden issues and only a specialist who has surveyed your loft in person can give you an accurate price.
What is included in a loft conversion quote?
Most quotes cover steelwork, floor strengthening, insulation, windows or dormer construction, plastering, basic electrics and a staircase. They usually do not cover drawings, engineer fees, planning fees, party wall fees, a bathroom, decoration or furniture. Always get each specialist to confirm in writing what is included in the quote before you compare the prices.
How do I get an accurate loft conversion cost for my property?
You should get at least three quotes from vetted specialists who have already done a survey of your property. A survey lets them properly check your roof, head height, access and any hidden issues before giving an pricing the job. Comparing a few quotes also helps you make sure that you are getting a fair price for the right work.
About This Guide
This guide was researched and put together by the LoftConversionUK editorial team using real quote request data from UK homeowners and we cross-checked it against live pricing from specialists in 519 UK towns and cities. We review and update this guide quarterly to stay accurate and up to date.