Guide to loft conversions

Can I convert my loft?

If you’re in need of more space at home or want to add value to your property, a loft conversion is a great option. However, before you go ahead, you should take some time to consider the costs and the laws you need to follow to build your new room.

Loft conversions don’t normally require planning permission, but you may need permission 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

If you want to convert your loft but aren’t sure about planning permissions, you can get a builder, architect or surveyor to visit your home and check if your loft space is suitable for a conversion, or if you need planning permission.

How to do a loft conversion

You need to follow a few steps for a high-quality loft conversion:

1. Carry out an initial assessment of your existing loft space

Check what type of roof you have, and how much head space you’ll have once the loft is converted (you need a minimum height of 2.2 metres for a loft conversion).

If you don’t feel confident carrying out these assessments yourself, get a builder, architect or surveyor to do it for you – they’ll also let you know if any planning permissions are required.

2. Find a reliable contractor

Get recommendations from friends, family and neighbours and have an initial chat with at least three firms for a good idea on costs.

If you want to carry out a few jobs yourself to save money, make it clear to the contractor what you want them to focus on instead. Once you’ve decided on which company to use, you should get a contract in place so you know who is responsible for what.

3. Let people know

Before work is to begin, you should inform your insurer, who need to know about any changes that will alter your home’s structure, habitability, security or value.

Don’t forget to prepare for disruption either – if you have a small child, you may want to avoid having a loft conversion done in winter due to cold weather – and let your neighbours know that you’re getting building work done.

How much does it cost to convert a loft?

The cost of a loft conversion depends on the type that is done.

A Velux loft conversion, which involves installing Velux windows to the roof, is usually the least expensive option, costing an average of £27,000.

A dormer is the most common type of loft conversion and involves a small flat roofed extension with a window. This costs an average of £45,000.

On the other hand, a hip to gable conversion costs around £55,000, allowing you to alter the shape of your roof structure to gain space.

A mansard loft conversion is the most expensive. It involves changing the whole shape of the existing roof so you end up with a flat roof and vertical outer walls. The average cost is £57,500.

How much value does a loft conversion add?

A loft conversion can take a lot of money, but it also adds up to 20% more value to your property.

The total added value, however, depends on the price of your property, where you live, and the type of loft conversion that is done.

Ready to start your loft conversion project? Learn more about home improvement loans.

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Published January 2023