Many construction contracts require subcontractors to secure General Liability “additional insured” status for the construction managers hiring them. With this protection, if the CM or Owner gets pulled into a suit due to the subcontractor’s negligence, the sub’s insurer will protect those upstream parties.
Insurers for subcontractors want not to have to provide any greater coverage to upstream parties than they absolutely have to.
Owners and Construction Managers should be specific and require exactly the coverage you intend for the sub to provide because in its 2013 update the Additional Insured Form 20 10 limits coverage to that required by the CM/ Sub contract.
One commonly found requirement is for the CM to require subs to provide insurance on a “primary and non-contributory basis” with specific dollar limits for insurance coverage.
Honest professionals will confess that Additional Insured questions are hideously complex and that clear answers are hard to come by. Making the requirements for downstream insurance in the main contract more clear however, increases the chances of getting what you expect.