Hello.
I am building my next residence as owner/builder in Brevard, North
Carolina, county of Transylvania.  Subcontractors are required for
electrical, plumbing, etc.  I'm encountering subcontractors who
operate small businesses and have elected not to adopt workman's
compensation coverage.  All such subcontractors have business licenses
and state professional licenses to do work in their specific trade. 
All of the small subcontractors have offered a signed agreement
relieving me of any responsibility for injury while on my job-site.
Question: Is such an agreement between me and a licensed subcontractor
legal and binding?

Thanks, Ron Payne