How much space around a roof window?

[Deansplit]

Hi

What's the minimum space required at top and bottom of a Velux window for using a man-made slate tile? I'm extending the side of the house and the pitched roof seems to be about 1600mm by the plans. Ideally I'd like to fit the 980mm Velux, but will it be too tight? Next one down (smallest) is 780, bit small)

thanks for any help.

 

[Alastairreid]

their is no minimum spacing! as long as there is room to accommodate both the top tray and bottom flashing.
then getting and keeping it watertight and of course the aesthetics.

 

[datarebal]

No Problem.