Helen, Sun tunnels are a great way of getting natural light into a building where a Velux window is not an option. However I would suggest using a Velux window if there is sufficient space. It should be possible to splay the 'cheeks' to the Velux window opening to maximise the light coming in. It will be rather fiddly, which is perhaps why the builder has offered up the sun tunnel as an alternative. Regards, Simon

Does this help? https://www.sterlingbuild.co.uk/page/pitched-roof-window-sizes

garage conversion TO KITCHEN/ LIVING ROOM with height of approx 7 feet. Thought some ceiling light would help give a sense of space.. Just need advice on recommended sizes.. Room is 4950 x 2420 .. we are looking to do approx half kitchen half living area.. we thought to have 1 skylight in kitchen area.. topics for best describing post are flat roof lighting.. kitchens

Thanks for the replies. @Ellie I think my partner got the idea of a horizontal one from a one pitch roof photo on here. they do look really nice. @oneplan that's a really good point re lining up windows if they are horizontal. Although I think long horizontal ones is the builders last choice as he says they'll take longer to install. We're paying a day rate so trying to get everything pinned down in advance and as slick as possible. Our internal layout is slightly different to the floor plan I added to the comments. The kitchen is going in the centre in the 'old' extension (front of the house is Victorian and existing extension is 1990s). The new extension will have the sitting area on the left and the dining area on the right (so the opposite of the floor plan). This is because the wood burner will need to go on the left side and we want the seating area around that. Do you have any thoughts on narrow vehicle windows one on either side for the gable roof? I'll try to find the photo of what I mean. Thanks