Call local contractors on a job by job basis and get estimates. Internet information is useless. This post is the obvious exception. Ron

I can't imagine why anyone would want to put narrow strips of roofing in hot asphalt or cold adhesive when they could cover the roof in a one piece (or factory seamed) single ply membrane. I would have to guess that the pieced together system is used for roofs with a lot of mechanical equipment and/or penetrations. If you want to include an internet link put it in the box provided and give it a name so we don't have to cut and paste to access it. Here is a link that might be useful: your roof link

Is the roof "really flat" or is there a slope to it? If "flat", reroof. Remove the existing roofing. Install tapered sleepers on the existing roof sheathing. Resheath. Reroof. Now the water will drain and not pool. That would be one way to look at it.

My son purchased his home several years ago. At that time, he knew that not having a railing around the flat roofed addition seen in the picture below was both a liability hazard and against code because the door up there allows access to that area. He wasn't concerned because he lived by himself and had no intention of using the area as a deck. Recently though his insurance carrier did an inspection of his property and notified him that he must correct the situation or his coverage would be dropped. There is a rubber type roof on the area and there has been no problems with it. My son would like to avoid compromising the roof with the installation of any posts for the necessary railings. As you can see, there are also gutters in the way of attaching posts on the outer edges if that's even possible Any suggestions how to remediate this problem would be greatly appreciated. Cross posted in the Home Repair forum