A few days after the electrician started, we had high winds and rain which revealed some serious leaks in the flashings around the monopitch roof light (chien assise). The roofer had not followed my detail, and had cut the roofing "felt" ( a microporous but waterproof reinforced material) too short, and had not turned it up behind the zinc flashing. With a strong wind behind it rain blew uphill and over the edges of the tiles !