large leaking tar flat roof

erbilliards

I own a large, old (late 1800's), mixed use building with a flat roof in upstate NY. The roof has been leaking to the point where I definately would like to do something about it this summer. The roof is in two large sections, roughly 50x65 and 65x65, so approx. 7200 sq ft. The roof is "flat" and it is what I am pretty sure is tar. Seams of what I imagine is tar paper are starting to show through.
I started doing my own research to figure out how I was going to attack this. I'm rapidly coming to the conclusion that I will need help. While I have done all the interior remodeling (framing, plumbing, electrical, etc.), I have never done any roofing work.
My first thought was to go over the existing roof with wood and a fully-adhered rubber roof. My reading leads me to believe this may be a bad idea due to trapping moisture? ripping the roof off seems a monster project. My rough investigation gave me a cost of $18,000 and that was doing it myself with 3-4 man help.
I may re-tar, but such a short lived solution, anyone have any thoughts? and possibly a product/application tips?
any and all thoughts are appreciated.
dave

Ed the Roofer

It depends on how severe the seams showing through are as you described.

Pictures would help immensely.

If the old hot asphalt glaze coat has deteriorated from lack of being maintained, yet otherwise remain flat and the surface coating is just wearing out, then a fresh application of a new hot asphalt can be mopped to the surface.

If they look like they are waving at you, but there are no sign of moisure entry, a heavy 43# base sheet and a minimim of a 2-ply to 3-ply 15# felt roof could be mopped down on top, depending on how many roof systems are currently installed.

With both options, the flashings should be resealed and have new roof cement applied to the seams. Also, any other maintenance issues should be addressed at the same time.

Ed

erbilliards

Ed,

Thank you for the informative reply. I will go up there Tommorrow or Tuesday and take pictures and post them. I do believe the surface coating is just wearing out, but mine is an opinion based on next to zero experience. Just judging from what I can see.

dave