How much does a loft conversion cost?

Loft conversion prices can vary between a few hundreds and several thousand pounds depending on the size of the conversion, the complexity of the work and whether you hire a professional to complete the job.

According to figures from The National Self Build and Renovation Centre, the average loft conversion should cost £498 per square metre if you source the materials and undertake most of the work yourself whilst it will cost £998 per square metre if you hire professionals to complete the job.

However, the actual cost can vary significantly depending on the size and extent of the conversion. Adding a bathroom to a loft conversion can add significant cost, as can the addition of several roof windows. Stairs must be enclosed with a fire door and you may have to reinforce ceiling joists or load bearing walls.

The property website Prime Location found that according to, a loft conversion in London by a specialist company usually costs up to £40,000, whilst in the rest of the UK the average is lower, at around £20,000 to £30,000.

The website estimates that a small insulated and plaster boarded loft conversion to include joists, two roof lights and stairs will cost between £15,000 and £17,000. A large loft conversion may be almost double this, at between £25,000 and £40,000.

When pricing up a loft conversion, it is vital that you don’t overspend or exceed your budget. According to Halifax, the UK’s leading mortgage lender, a loft conversion should add an average of £24,981 to the value of your home. Prime Location estimated in 2008 that ‘a loft conversion can add an extra 10 per cent to a property's value.’

So, when budgeting for a loft conversion, make sure you have an idea of what value the conversion will add to your home, and make sure you don’t exceed the budget you have.

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