So essentially, as I expected, my roof is not "water-proof" at all. I am gathering photo evidence and will be calling the roofing contractor soon. So with regards to the exposed wood problem, what is normally done to seal the roof and to ensure it is water-proof? Should drip edges be installed at all edges? Chicago --> Is the cracked underlayment in the third picture? Regarding the chimney flashing, are they supposed to use some sort of sheet metal? And also, what is the concern with using nails in the flashing? UPDATE: I just consulted my house inspector who inspected my house in November prior to my purchasing of the house. He told me that it is quite common to expose the plywood sheathing, but is not good practice. I checked my roofing contract and there is mention of drip edges. Can I hire another company to install drip edges and thus rectify the problem of exposed wood, or will extensive work be required to solve this problem?