Dormer loft conversion

How Much Does a Loft Conversion Cost

In 2024 the average cost of loft conversion in London is between £45,000 and £90,000. Most Londoners convert an attic into a dormer because it adds extra space and light.

A loft conversion is a great way to add extra space to your home and increase the value of your property. A loft conversion is the type of construction work that requires lots of planning and preparation. Cost is one of the things you need to consider before converting your attic.

loft room with a triangle shape window

The roof conversion cost in London is different, unlike other cities in the UK. The prices of materials have significantly risen, and loft builders are still quoting you by the old prices. So you don't run away, and they can win your job. With the help of this guide, you can challenge your builder on the validity of their quote. Or to find out a ballpark figure before getting onboard with your loft conversion project.

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The loft extension price depends on

  • type of conversion
  • type of roof
  • type of lighting in a loft conversion
  • type of windows
  • number of windows
  • size of the project
  • fixtures and textures
  • nature of the exterior
  • client’s custom requirements
  • location

Fint the cost of:


Dormer extension

The price of dormer loft conversion largely depends on the specification of the building and the number of dormers. You can choose to have dormers on the roof as well as side dormers.

The cost of dormer loft conversion consists of dormer windows cost, dormer roof cost, staircase cost, added insulation cost, costs of electrics, lighting and heating, as well as the cost of remodeling works. You must be prepared to pay at least £65.000.

By creating extra space and not being restricted by sloping walls, dormers can boost property values quite significantly relative to a standard loft conversion.

Hip to Gable

The size of the overall loft has a significant impact on hip to gable loft conversion cost. The average loft conversion price is £75,000.


velux attic extension

What is great about this type of loft conversion is that less work needs to be done and, of course, this affects the price. The average velux loft conversion price is £45,000.

Loft Conversion with Ensuite

Adding ensuite will result in a higher bill. So, you should expect to pay around £50,000 - £60,000 for a loft conversion with ensuite

Terraced House Loft Conversion Cost

The cost of a terraced house loft conversion depends on many factors such as the project’s size, internal specifications and many others. Traditionally, terrace homeowners in London expect to pay at least £65,000 for a loft conversion.


3d mansard drawing

A mansard loft conversion is the most expensive type of conversion because it involves changing the entire roof structure and adding a whole new storey to the building. You need to pay £70,000 to get the construction work done.

London Loft conversion price

Loft type Price starting from
Dormer £65,000
Hip to gable £75,000
Velux £45,000
With ensuite £50,000
Terraced £65,000
Mansard £70,000
Small basic loft £30,000

Breakdown of involved professional fees

To ensure you meet a realistic budget, you need to consider professional fees. These fees include planning fees, which are payable to the local council for planning permission, as well as design fees for architectural plans and structural calculations. Additionally, if the loft conversion involves work on shared walls, you may need to pay party wall fees to ensure that the work doesn't adversely affect your neighbours. Finally, building control fees are charged by the local authority to ensure the conversion meets the required building regulations.

If you want to know exactly how much does a loft conversion cost in London you will need to get a quote form London loft conversion specialist. If it is not your property then an average cost of loft conversion varies between £45,000 and £90,000 depending on your requirement. Basic (small) conversion is the cheapest option. Even with the budget of £30,000, you’ll be able to get a small loft converted if you willing to compromise the quality of work or there isn’t much structural work involved.

Clara Annesley

Clara Annesley is an interior design and construction content writer. She holds a BSc (Hons) in Architectural Design Technology from the University of West London. Clara specialises in residential construction for topics like health & safety, architectural design and writing cost guides for renovation and remodelling projects.