How Much Is a Loft Conversion in the UK?
- Corsol Conversions
- Dec 18
- 5 min read
If you’re looking at your loft and thinking, “That could be a proper room,” you’re not alone. At Corsol, we speak to homeowners every week who want an extra bedroom, home office, or a quieter space away from the main living areas. The first thing most people want to know is the same: how much is it going to cost me?
The honest answer is that there’s a range, and it depends on the type of loft conversion, your roof structure, and what you’re building the space for.
Below, we outline the real costs of loft conversions in the UK, what a basic build usually includes, and the factors that impact the price.
Typical Loft Conversion Costs for UK Homes
Most loft conversions in the UK tend to land somewhere between £30,000 and £70,000+.
As a general guide:
A basic loft conversion often starts from around £30,000 to £40,000.
Mid-range conversions commonly sit around £40,000 to £55,000.
Large dormers, complex roof alterations, and high-spec finishes can take the total beyond £60,000 to £70,000+.
Those numbers are there to help you plan, but the only way to get a reliable figure is to assess the loft itself.
Two houses on the same street can have very different costs if one needs structural changes, a new staircase position, or more complicated steelwork.
Basic Loft Conversion Cost
When people search for basic loft conversion cost, they usually mean the simplest conversion that creates a safe, comfortable room without major roof changes.
A basic conversion often involves:
Strengthening the floor structure
Insulation to meet building regulations
Roof windows (often Velux-style)
A compliant staircase
Electrics, lighting, and heating
Plastering and standard finishes
In many homes, a basic loft conversion starts from £30,000 to £40,000, but there’s an important catch.
If the loft has limited head height, poor access, or requires additional steelwork to support the new floor and roof loads, it stops being “basic” quickly. That is where costs start moving up.
Loft Conversion Types and Typical UK Costs
Here’s how the main loft conversion types compare in the UK.
Rooflight Loft Conversion Costs
A rooflight conversion keeps the roof shape the same and adds roof windows rather than changing the structure.
It can be a good option if your loft already has decent head height and the layout works well with the staircase.
Typical cost: £30,000 to £40,000.
Dormer Loft Conversion Costs
Dormers are extremely common because they add usable floor space and headroom. If you want a bigger bedroom, a master suite, or a layout that feels like a natural part of the house, a dormer often makes the most sense.
Typical cost: £40,000 to £60,000+, depending on size and finish.
Hip-to-Gable Loft Conversion Costs
This involves extending the sloping side of the roof into a vertical wall to create more internal space. It is often used on semi-detached or detached properties and can make a big difference to layout options.
Typical cost: £45,000 to £65,000+.
Mansard Loft Conversion Costs
Mansards involve significant roof alteration and often need planning permission. They offer excellent space, but they are usually the most expensive option due to the amount of structural work involved.
Typical cost: £60,000 to £80,000+.
What Actually Drives Loft Conversion Costs Up?
From a specialist point of view, the biggest cost drivers tend to be structural and layout-related rather than cosmetic.
Head height and roof structure matter more than most people expect.
If your loft is tight on height, it may require structural changes to make the space compliant and comfortable. The existing roof type also affects how much work is needed.
Steelwork and floor strengthening are other major factors. Loft conversions need a new structural floor, and many require steel beams to support the load properly.
The amount of steel depends on your home’s structure and design.
Staircase position is a big one, too. Stairs need to meet building regs, and the best position is not always the easiest one.
Sometimes the stair design is straightforward; other times it requires changes to existing rooms.
Bathrooms add cost quickly. If you want an en-suite, you’re adding plumbing, ventilation, soil connections, extra electrics, and a higher finish expectation.
It is absolutely doable, but it changes the overall budget.
Finishes and joinery can move the final figure. Built-in wardrobes, bespoke storage in the eaves, upgraded doors, premium flooring, and feature lighting all add up.
What’s Usually Included in a Loft Conversion Quote?
This varies between companies, so it’s worth checking, but a proper loft conversion quote commonly includes:
Structural work and steel
Roof alterations (if needed)
Insulation, plastering, and internal walls
Staircase installation
Electrics and plumbing (where applicable)
Windows or dormer build
Building regulations compliance
It may not include things like decorating, fitted furniture, or bathroom fittings unless specified. A clear breakdown avoids confusion later.
Planning Permission and Building Regulations
A lot of loft conversions can be completed under permitted development, but not all. Dormers, mansards, and homes in certain areas can require planning permission.
Even if planning is not required, building regulations approval always is.At Corsol, we always build to current building regulations because that is what keeps the conversion safe, compliant, and sellable. If you ever plan to sell your home, you want the paperwork and sign-off done properly.
How to Keep Loft Conversion Costs Under Control
You do not need to cut corners to keep a loft conversion affordable, but you do need to make good decisions early.
Keeping the layout simple helps. A straightforward room with a clean staircase route usually costs less than multiple rooms and complex structural changes.
Being clear on finishes upfront matters too. It is easier to budget accurately when you know if you want basic skirting and carpet, or fitted joinery and premium flooring.
If you are thinking about an en-suite, decide early. Adding it later can cause redesign and extra work, which increases cost.
Final Thoughts
So, how much is a loft conversion in the UK? Most projects sit between £30,000 and £70,000+, with a basic loft conversion cost often starting around £30,000 to £40,000 for a simpler rooflight-style conversion, and moving up as soon as structural work, dormers, or bathrooms come into play.
If you want an accurate figure for your home, the next step is a proper assessment of your loft. That is the only way to see what is possible and what the cost will look like in real terms.
If you’re based in Bristol and you’re considering a loft conversion, Corsol can advise on what’s achievable and what budget range makes sense for your property.
Get a free, no-obligation quote here or contact us.
FAQs
How much does a loft conversion cost in the UK in 2026?
Many loft conversions in the UK cost between £30,000 and £70,000+, depending on the conversion type, structural work needed, and the level of finish.
What is the cheapest type of loft conversion?
A rooflight (Velux-style) conversion is usually the cheapest because it keeps the roof structure the same and focuses on internal conversion work.
Does adding an en-suite increase loft conversion cost a lot?
Yes. An en-suite typically increases cost because it adds plumbing, ventilation, electrical work, and higher finishing requirements. The exact amount depends on the location of existing soil stacks and layout.
Do I need planning permission for a loft conversion?
Not always. Many loft conversions fall under permitted development, but this depends on the type of conversion and your property. Building regulations approval is always required.
How long does a loft conversion take?
Timescales vary by design and complexity, but many loft conversions take several weeks from start to finish once work begins.
