Sounds like it might be a commercial job. Consider looking at the NRCA membership list for that area.
When it comes to long term roofing performance its always in the details. The cheaper guys don't address the details. Make sure any proposal includes:
- All materials to be installed in accordance with NRCA roofing manual guidelines and specifications
- All materials to be installed in accordance with manufacturer specifications
Verify that proposals include information on venting, flashings, types of terminations to penetrations, how parapet walls and copers will be addressed, how many roof layers are already present, if debris will be hauled away, how plants will be protected, what elevation the roof will be accessed from, applicable window protection, etc. if the information is not in the proposal the contractor likely isn't planning on doing good long term work.
Most municipalities only allow 2-3 roof layers. Someone should be doing a core sample to assess how many layers are present. Depending on what type of roof or building this is your guy may want to consider adding insulation board. Depending on age, occupancy and adopted energy codes for the municipality meeting insulation value may be required.
Hope that helps.
