lead box valleys roof

[khughes]

hi, am getting an extension done and the builders have just put roof rafters in, which come to slightly above one of the back windows. they've assured me that they will use a lead box valley to allow for opening of the window. i'm not convinced that i like the look of it, they say that the pitch of the roof was necessary to be so high but i don't think so as my neighbour in an identical house has one that at it's top height the roof is still below the upper bedroom window sills. any comments on this from personal experience?

 

[Leo]

Your choice of roof covering will dictate the angles required to keep it watertight. Tiles laid at too shallow an angle will let water in.
Leo