Here in NJ the Lic. Contractor is responsible for the installation.
The second issue, depending on the "notes" on the prints, the contractor can be liable for "mistakes" on prints. Notes to the effect of "verify conditions in field" "site inspection required prior to submitting bid", or other legal jargon to this effect. Also, the size of the job has impact, and you may "Change Order". A good relationship with the Project Manager, or GC also helps. But, most of all PLAN REVIEW and read and understand the notes and specs
John
