How Much Does a Loft Conversion Cost in the UK?
A loft conversion is one of the best-value ways to add a bedroom and value to a house without extending the footprint. The type of conversion is the main cost driver.
A simple Velux conversion at the low end; a large mansard with en-suite at the top.
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Cost by conversion type
What affects the price
- •Conversion type — a rooflight (Velux) conversion is cheapest as it keeps the existing roof shape; dormers and mansards rebuild part of the roof.
- •Head height — if the ridge is too low, the floor may need lowering or the roof raising, which is costly.
- •Staircase position and any structural steelwork.
- •Adding an en-suite bathroom.
- •Building Regulations, party-wall agreements and (for some) planning permission.
Regional price variation
Labour is the biggest regional swing. London and the South East typically run 20–30% above the national average, while the North of England, Scotland and Wales tend to sit 5–15% below it. Material prices are fairly consistent nationwide — it is day rates that move the total. The ranges on this page assume South of England pricing unless stated.
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Frequently asked questions
How much does a loft conversion cost in the UK?
A loft conversion typically costs £20,000–£70,000. A simple Velux conversion is £20,000–£35,000, a dormer £30,000–£50,000, a hip-to-gable £35,000–£60,000 and a mansard £45,000–£70,000 or more.
Does a loft conversion add value?
A loft conversion usually adds around 15–20% to a property’s value and almost always adds a usable bedroom, so it is one of the highest-return home improvements — often recouping most or all of its cost.
Do I need planning permission for a loft conversion?
Most loft conversions fall under permitted development and do not need planning permission, but you always need Building Regulations approval. Dormers on the front of the house, conservation areas and volume limits can trigger a planning application — check with your council.