A unit price needs a clear measurement basis and description of included labor and material. A figure per sheet, area, or linear length is difficult to compare when each bidder defines the unit differently.
What to do next
Ask how quantities will be measured and verified. Confirm whether removal, installation, disposal, and related restoration are included. Keep the definitions in the contract so additional work can be evaluated using the agreed scope rather than a newly interpreted unit.
Related Perkins guidance
Contact Perkins Roofing to discuss your roof and the appropriate next step.