What will your loft conversion cost?
Answer six quick questions and see a guide price for your loft straight away. Then one checked local loft builder calls you with an exact quote.
- Free, with no obligation to go ahead
- One builder contacts you, not a crowd
- Velux, dormer, hip-to-gable and mansard
Get your estimate
Takes about 60 seconds.
How it works
You stay in control at every step.
Tell us about your loft
Type of conversion, your house, timing and budget. No drawings needed.
See your guide price
You get a typical price range for your type of loft conversion as soon as you finish.
A local builder calls you
We pass your details to one checked loft builder near you, who visits and gives you an exact quote.
Typical loft conversion costs in 2026
Guide prices for a loft of about 30m², excluding VAT. Roof shape, head height and finish move the final price.
Ranges from published 2026 UK cost guides, including Checkatrade. They're a starting point, not a quote.
Common questions
Is my loft suitable?
The main test is head height. As a rule of thumb, you want at least 2.2m from the top of the floor joists to the underside of the ridge. A builder will measure it on their visit.
Do I need planning permission?
Velux and many rear dormer conversions fall under permitted development. Hip-to-gable conversions often need checking, and mansard conversions usually need a planning application. Your builder or your local council will confirm for your house.
How long does it take?
Around 4 to 6 weeks on site for a Velux conversion, and roughly 6 to 12 weeks for dormer and hip-to-gable work. Mansards take longer.
Who are you?
Extension Check is an independent introduction service, not a building company. We give you a guide price and introduce you to one local builder we've checked for reviews, company records and insurance. It's free for you; builders pay us for introductions.
Will lots of companies call me?
No. We share your details with one builder only, and only because you asked us to. You can ask us to delete your details at any time.
Find out what your loft will cost
Six questions, a guide price, and one quote from a local builder.
Get my estimate