In 40 seconds
Fitting a skylight or roof window in the UK usually costs roughly £900–£2,600 per unit installed, with most standard Velux roof windows landing around £1,100 supply and fit and a flat-roof rooflight typically £800–£1,500. The price is driven by the unit you choose, your roof type and access, and whether scaffolding is needed — third-party scaffolding can add around £500, and flashing kits roughly £80–£180. For most homes a skylight is permitted development and needs no planning permission, provided it sits no more than 150mm proud of the roof slope and not above the ridge; the main exceptions are listed buildings and conservation areas. The honest answer is always a range, because it depends on the rooflight, the roof and the access.
Most skylight guidance is published by firms supplying or fitting them, so the numbers tend to be optimistic and the planning rules glossed over. The pages below give honest cost ranges, separate Velux, flat-roof and lantern pricing, and set out exactly when planning permission applies — before you take a single quote.