I have been roofing for 40 years, it is 90# granulated roll roofing or felt. It will hold for 8 to 10 years if it's properly sealed. I would have used a torch down like derby gum or a rubber I like whale skin, but for a less expensive roof I would go ahead with the 90 with a 4" gravel guard drip down both sides snipped, folded and sealed at the bottom edge. With a T-drip on the drain edge, with an 8" wide layer of Bull and glass around the outer edge on top of the 90, with a nice smooth taper so water can't stand against the bull and glass, except on the drain edge with the T-drip. The T- drip should be under the 90 and that is the side you should go up on if it is absolutely necessary. Then stay off the roof. Watch out that bull will get on your ear if you talk about it on the phone!
