Getting a loft conversion: what you need to know

Converting your loft can give you space to expand and add value to your home. So how much does a loft conversion cost, and what do you need to keep in mind?

Is your house suitable for a loft conversion?

This is the number one thing to check before you begin. The key point for consideration is size - you don't want to end up with a room you can't stand up in.

According to the HomeOwners Alliance, you need at least 2.5m between the top of the roof joist (where the floor will be) and the bottom of the ridgeboard (the board running along the highest point of your roof space). You also want enough floor space – usually about 5.5m side to side and 7.5m front to back.1

How much does a loft conversion cost?

The website homebuilding.co.uk gives the following estimates:

  • A simple loft conversion could start at around £15,000
  • A loft conversion with added dormer windows and an en-suite could cost £35,000-£45,000
  • A loft conversion that changes the shape of your roof could cost upwards of £40,0002

These figures are just a guide. Costs will depend on the size and shape of your loft, and where you live. They also only cover the basics. It’s a good idea to get several quotes before you begin work.

Who should handle your loft conversion?

It might seem cheaper to do things yourself, but a loft conversion is a big job and it may be a good idea to go with an expert. You can use one or a combination of these options:

  • A specialist loft conversion company can offer you the complete package, from planning to painting and decorating
  • An architect can draw up something unique and can usually help with regulations and finding builders
  • A general builder can handle the process, but it's worth making sure they have loft conversion experience

Do loft conversions need planning permission?

Usually, loft conversions within your existing roof space don't need planning permission, but always check. In some situations you will need permission, for example if:

  • You live in a conservation area or other protected area
  • You want to raise the height of your roof or extend out to the side
  • Your loft conversion is particularly large (more than 40 cubic metres of space)
  • You want clear glass side windows that will overlook your neighbours

Building regulations for loft conversions

All loft conversions need building regulation approval. Building regulations cover things like fire safety, structural strength and insulation.

You'll need to make a building regulations application to a building control body (BCB) before you begin work, and may have to submit detailed plans. A BCB can be your local authority or a private approved inspector who will tell your local authority about the work. Your builder or architect should help you through this process.

What next?

A loft conversion can be a lot of work, but it can also pay off. The HomeOwners Alliance estimates it can add up to 20% of value to a property.1


If you would like to use a personal loan to fund your loft conversion, it’s worth also looking at your options and the potential cost. Use a loan calculator to get an estimate of what your repayments would be based upon the amount you want to borrow and how long you’d like to borrow for.

Disclaimer: please remember...

We are a bank, not DIY gurus. We provide this information as a helpful guide. However, if you're thinking of getting a loft conversion, please carry out your own research and don't assume these details are 100% correct or the most up to date available.