We are currently planning our extension and want to include a sky light around 1.5m x 3m in size. I really like a modern looking flat one in the flat roof I think the lantern ones are not as modern looking. However we have been advised that flat roof lights hold water for days after rainfall as there is no natural run off. So we would have to wait for it to evaporate. Does anyone have any experience of this and can anyone recommend either way? Thanks in advance