In 40 seconds
A loft conversion turns unused roof space into a habitable room — typically a bedroom, en suite, home office or playroom — without extending the house outwards. Most conversions fall within permitted development and do not need planning permission, but building regulations approval is always required to create a safe, mortgageable room. The four main types are Velux (skylights only), dormer (box projection), hip-to-gable (rebuilds a hipped end) and mansard (near-vertical walls). Costs typically range from £20,000 for a simple Velux to £75,000+ for a mansard. The key suitability test is head height — you need at least 2.2 metres at the ridge. A conversion typically adds 15–25% to a property’s value when it creates a genuine extra bedroom.