Hi all, this is my first post so please be gentle. My knowledge is limited to what I've been able to Google. I'm definitely not a roofing expert and I'm learning as I go, although I have done lots of DIY elsewhere and I'm happy to take on big projects.
We have a new rooflight going into the pitched roof of our new kitchen. The roof is existing and a hole has been cut. The rooflight extends to the end of the gable and meets a piece of vertical glass forming a window, for which there is also a hole in the gable end. See attached pictures. The blue arrows are potential water flow routes. There is a small upstand, shown in brown and the rooflight is about 3m long. I've only drawn part of it. The frame (in grey) and upstand actually go all the way around 3 sides.
My primary question is about designing the flashing and drainage at the back of the rooflight on the high side of the roof. My thought was to use lead flashing and slope the upstand slightly away from the gable to direct the water away from the edge.
Can I do this with lead on such a small slope (perhaps 1:80) and can I just use <1.5m lead lengths and lap it 150mm (or more?) to ensure it doesn't leak. Is there a better option I'm not thinking of? How should I seal it, or should I not?