Additional insured status is one of the most requested—and most misunderstood—requirements in construction contracts. Owners require it from general contractors, GCs require it from subcontractors, and yet few parties fully understand what it actually provides, what form it must take, or how it responds when a claim is made. Here are four key concepts our construction clients need to understand:
1. What Additional Insured Status Is—and Why It Matters
What It Is: An additional insured is a party—other than the named insured—who is extended coverage under someone else’s insurance policy. In construction, owners typically require that general contractors name them as additional insureds on the GC’s Commercial General Liability (CGL) policy. GCs, in turn, flow this requirement down to subcontractors. The result: if a claim arises from the contractor’s work, the owner (or upstream contractor) can tender that claim directly to the contractor’s insurer rather than relying solely on their own policy.
The Risk for Your Client: Without proper additional insured status, an owner or GC who is sued for bodily injury or property damage arising from a subcontractor’s work must defend and pay that claim through their own policy—exhausting their own limits and triggering their own experience. Additional insured status shifts that burden to the party whose work created the risk. When a subcontractor’s employee is injured on-site and sues the GC, a properly structured additional insured endorsement means the subcontractor’s CGL insurer steps in to defend the GC and pay any judgment.
Whether you are the party requiring additional insured status or the party providing it—you need to treat this as more than a checkbox on a certificate of insurance. The value of additional insured coverage depends entirely on the form of endorsement used, the scope of coverage provided, and whether the policy is written on a primary and non-contributory basis. Each of those elements requires specific contract language and active verification.
2. The Different Types of Additional Insured Endorsements
What It Is: Not all additional insured endorsements are equal. The two most common ISO forms used in construction are the CG 20 10 (covering ongoing operations—work in progress during the project) and the CG 20 37 (covering completed operations—claims arising after the project is finished). Owners and GCs should require both. A CG 20 10 alone leaves the upstream party exposed to completed operations claims, which are often the most significant—defects discovered months or years after project completion.
The Risk for You: Two additional distinctions matter significantly. First, scheduled vs. blanket endorsements: a scheduled additional insured endorsement names a specific party and requires the insurer to manually add each additional insured —creating administrative delays and the risk of omission. A blanket additional insured endorsement automatically extends additional insured status to any party required by written contract, eliminating that gap. Second, the 2013 ISO form revisions narrowed additional insured coverage to apply only to liability “caused in whole or in part” by the named insured’s acts or omissions—meaning an additional insured can no longer recover for losses entirely of their own making. Some states have not adopted these narrower forms; others have.
When drafting or reviewing contract insurance requirements, specify the exact endorsement forms required: CG 20 10 and CG 20 37 (or their equivalent), on a blanket basis. Do not accept language that simply says “additional insured endorsement” without specifying the form. The difference between a broad pre-2013 endorsement and a narrow post-2013 form can determine whether a significant claim is covered.
3. Primary and Non-Contributory Coverage: The Critical Modifier
What It Is: Being named as an additional insured does not automatically mean the contractor’s policy pays first. By default, when both the additional insured’s own policy and the named insured’s policy provide coverage for the same claim, each policy shares the loss in proportion to its limits—a concept called “contribution.” To override this default, contracts must require that the additional insured endorsement be written on a primary and non-contributory basis, meaning the contractor’s policy responds first and in full before the additional insured’s own policy is triggered at all.
The Risk for You: Without primary and non-contributory language, an owner who tenders a construction claim to a GC’s insurer may find that insurer seeking contribution from the owner’s own policy—eroding the owner’s limits and increasing their premium at renewal. For a GC requiring additional insured status from a subcontractor, the same problem applies: if the sub’s endorsement is not primary and non-contributory, the GC’s own CGL insurer may be required to share the loss on a claim that should have been the sub’s sole responsibility.
Every contract requiring additional insured status should also require that the coverage be “primary and non-contributory with respect to any other insurance or self-insurance maintained by the additional insured.” This language must appear in the contract, and the additional insured endorsement itself must reflect it. A certificate of insurance that states “primary and non-contributory” without a corresponding endorsement does not bind the insurer—only the endorsement does.
4. Verification: Why Certificates of Insurance Are Not Enough
What It Is: A certificate of insurance (COI) is a summary document—it provides evidence that a policy exists, but it does not create, modify, or guarantee coverage. The actual additional insured endorsement, attached to and made part of the policy, is the document that binds the insurer. Certificates routinely contain errors, reference endorsements that were never issued, or are simply outdated. When a claim is made, the insurer looks to the policy and its endorsements—not the certificate—to determine whether additional insured coverage applies.
The Risk for You: Relying on a certificate alone creates real exposure. A GC who collects COIs from subcontractors at the start of a project but never requests the actual endorsements may discover—after a significant claim—that the sub’s insurer disputes additional insured coverage because the endorsement was never issued, lapsed, or applied a narrower form than required by contract. At that point, the GC is defending a claim on their own policy for a loss that should have been the subcontractor’s responsibility.
You should request the actual additional insured endorsements—not just the certificate—from every subcontractor before work begins. Confirm that the endorsement names the correct entities (both the GC and the owner, if required by contract), references both ongoing and completed operations, and includes primary and non-contributory language. Build this verification into your standard subcontractor onboarding process. A brief review at the outset is far less costly than litigating coverage after a serious claim.
Strengthening Our Partnership
Additional insured status, when properly structured and verified, is one of the most effective risk transfer tools available to construction clients. When it is handled as an afterthought—a box checked on a certificate rather than a carefully negotiated and confirmed endorsement—it can fail precisely when it is needed most. By helping our clients understand what to require, what to verify, and what gaps to watch for, Risk Averse Insurance delivers the kind of proactive risk management guidance that sets us apart as a trusted advisor.
