DATA-BACKED GUIDE · UPDATED JULY 2026
Loft conversion cost UK: room-in-roof, dormer and hip-to-gable prices
A loft conversion is one of the most reliable ways to add a bedroom or office without losing garden space. The catch is that no two lofts are the same, so the quotes people get vary a lot. The real prices below come from actual prices, so you can see what other homeowners across the UK have paid rather than a showroom guess.
The quick version
- The three common types, room-in-roof, dormer and hip-to-gable, sit at different price points, with a simple room-in-roof usually the cheapest.
- Head height and roof structure decide a lot. Trussed roofs need more steelwork than older cut roofs, which pushes the cost up.
- Most loft conversions fall under permitted development if they stay within the size limits, so full planning permission is often not needed.
- Building regulations sign-off is a separate step from planning and is required for the stairs, fire safety and insulation.
What people actually paid
Real prices, in people's own words
- £15,000“£15k”
- £15,000“£15k”
- £38,000“Room only (no dormer) everything but carpets for 38k”
- £38,000“38k”
- £50,000“50k for a hip to gable plus dormer”
- £50,000“50k inc vat”
Genuine amounts posted publicly. We publish the price and the quote, never the person.
Why the price varies so much
Two lofts that look identical from the street can produce very different quotes. It comes down to the roof structure, the available head height, where the new staircase has to land, and how much steel is needed to carry the floor. A conversion with an ensuite costs more than a plain bedroom because of the plumbing runs and waterproofing. Access matters too, since a terraced house with no side access means everything is carried through the home. Add the type of dormer or the choice of rooflights, and you can see why one street throws up such a wide spread of prices.
How to pay less
- Get at least three quotes from firms that have done your style of roof before, and check they include the structural steel and building control fees.
- Rooflight or Velux conversions are cheaper than a full dormer, so if you already have the head height, you may not need to rebuild the roofline.
- Keep the bathroom close to existing soil pipes to cut plumbing costs, rather than putting it at the far end of the loft.
- Book the work outside the busy spring and summer window when builders are stretched and prices firm up.
Common questions
Do I need planning permission for a loft conversion?
Often no. Most loft conversions fall under permitted development as long as they stay within the volume limits and do not extend beyond the roof slope at the front. You will still need building regulations sign-off, which covers the stairs, fire escape and insulation and is a separate process from planning.
How long does a loft conversion take?
A straightforward room-in-roof or rooflight conversion is usually the quickest, while a dormer or hip-to-gable takes longer because more of the roof is opened up and rebuilt. Weather and steel delivery can stretch the timeline, so ask your builder for a realistic schedule in writing.
Will VAT be added to the quote?
Most building work carries 20% VAT, so check whether a quote includes it or not before you compare figures. A price that looks lower may simply have left the VAT off, which changes the comparison completely.