I’m actually just finishing up a roof restoration project on a similar building, so I figured I’d share my experience. I’m in the South Bend/Granger, Northern Indiana area. My building is a 28,800 SF PEMB built in 1996. The existing metal roof was still pretty solid overall, although we did have a few areas that were leaking and obviously had some aging issues. I ended up going with a Fluid Applied Roofing system using FiberSeal, which is a polyurethane-acrylic hybrid rather than silicone. We did the necessary prep, flashing/seam work, repairs, etc. and the system carries a 15-year warranty. The contractor I used was out of the Chicago area, and the total project came in at $106,000, or about $3.68/SF. For me, the deciding factor was that the existing metal roof was still in good enough condition that I didn’t want to tear it off and replace it if I could get another 15+ years out of the existing roof. I’m just finishing the project now, down to manufactures inspection of insulation, so obviously I can’t speak to how it will perform 10–15 years down the road. But so far, I’m happy with the process and the finished product. If your 12,300 SF roof is still mostly solid and you’re mainly dealing with fasteners, flashing, seams and some rust, I’d definitely get a couple of restoration/coating bids along with a replacement quote. It gives you a pretty good apples-to-apples comparison before making the decision.