In most cases, the installation of a roof lantern does not require planning permission in the UK if it adheres to specific permitted development guidelines. These guidelines state that the roof lantern should not extend more than 150mm above the existing roof's slope and its height should not exceed the highest point of the roof. However, the need for planning permission may vary depending on local regulations, considering factors such as size, placement and impact on neighbours. To determine if planning permission is necessary for a specific roof lantern installation, it is advisable to consult the local planning authority or even an architect.