What a loft conversion costs
Most loft conversions cost between £25,000 and £60,000 in 2026. A simple rooflight (Velux) conversion is cheapest at around £25,000–£40,000; a dormer runs £35,000–£55,000; and a hip-to-gable or mansard — which change the roof shape for more space — sit at £45,000–£75,000+.
The four main types
A rooflight conversion adds windows without changing the roofline (cheapest, but you keep the existing headroom). A dormer adds a box that increases floor space and headroom. A hip-to-gable extends a sloping side wall upward, and a mansard rebuilds the roof for the most space — the priciest option.
Will my loft convert?
The key is headroom: you generally need around 2.2–2.4m from floor to ridge. Roof structure matters too — older “cut” roofs are easier than modern trussed roofs, which need reinforcing. A specialist can tell you in a single visit.
Do I need planning permission?
Many loft conversions fall under permitted development, but front dormers, work in conservation areas, and anything over the volume limits need permission. All loft conversions need building regulations sign-off, especially for the staircase and fire escape.
Get a quote for your loft
The cheapest room you’ll ever add is the one you already have. Tell us about your loft and we’ll match you with a vetted local conversion specialist.