We also found an interesting situation. The top layer of shingles had been roofed over by putting 2x4 sleepers on the old roof, and new decking over the short roof. Most of our preparation for this phase of the project was deciding on materials for the roof. The type of shingles and how the gutters would be repaired were the main items to research. I have already discussed the shingle decisions, now let me discuss the options for the box gutters.
Box gutters are gutters that are built into the roof detail.
The rafter tails are extended and the gutter is formed in the end of that section. The main part of the box lining is constructed with a skeleton of exterior grade plywood. The board joints are not made water tight. The reason is so that if there is a leak in the waterproof liner, the water leaks through and drips through the soffit, so it is noticed right away. If the wooden part is sealed, the water stays put in that part of the gutter and starts the rotting process.