Porch roof replacement

[baxtergk]

To all, I've recently been asked to bid on a small job (I'm trying to keep it small) for replacing an existing porch roof. If you refer to the attached pdf file (2 pages) you can see what's being proposed. The existing roof is corrugated metal sitting on understructed 2x4s hanging off of the subfacia. The owner wants a new roof that is higher, properly structured and shingled. It's the shingle part that has me concerned. If I tie into the existing roof on two sides with a low pitch shed type porch roof and the shingles are running in the same orientation as the main roof, I'm afraid of water coming off of the gable side will be able to flow under those shingles. I could support the roof at the low end with free standing 4x4s posts and keep the porch roof off of the gable roof entirely, but I would have to gutter the eave which is not the most attractive. Suggestions?

[stuart80]

Replace the shingles by following the rows to the right and left of the new patched area by securing using roofing nails.

[matheus]

The slope of your shed roof looks to be to shallow for shingles alone. You will have to do torch on or ice and water then shingle over that