A $9.5 million office renovation in Chicago was completed in April. In October, a former tenant of an adjacent suite files suit claiming that construction vibration damaged the building's structural system and caused the tenant's space to become uninhabitable. The GC is named as a defendant along with the excavation subcontractor. The GC demands defense from the sub's insurer under the additional insured endorsement.
The sub's insurer declines. The policy contains a CG 20 10 endorsement - ongoing operations only. The damage claim is a completed operations claim. The GC's contract required both CG 20 10 and CG 20 37. The COI checkboxes showed "additional insured - yes." Neither the project manager nor the contract administrator verified which endorsement form had actually been issued.
The GC's own umbrella policy ultimately responds. Cost: $1.4 million in defense and settlement.
Why GCs Require Additional Insured Status
General contractors occupy the top of the subcontract chain and bear the broadest legal exposure on a construction project. Owners, adjacent property owners, and injured third parties name the GC in virtually every construction-related lawsuit regardless of which trade actually performed the work. This is not necessarily unjust - GCs do bear significant responsibility for site safety and project quality - but it means GC insurance programs absorb a disproportionate share of construction claim costs.
The additional insured requirement shifts some of that cost back to the trade responsible for the underlying work. When the GC is properly named as an additional insured on the sub's GL policy, the sub's carrier defends the GC and pays covered damages first. The GC's policy responds only after the sub's limits are exhausted - or if the AI coverage has a gap.
For this mechanism to work, the AI coverage must: (1) actually exist as a policy endorsement, (2) cover the right scope of operations, and (3) name the correct GC entity.
CG 20 10: Ongoing Operations Coverage
The ISO CG 20 10 endorsement adds the GC as an additional insured on the sub's commercial general liability policy for bodily injury and property damage arising from the sub's ongoing operations performed for the GC.
What it covers: Third-party claims arising while the sub is actively performing work on the project. Worker injuries (if a third party is involved), property damage to adjacent properties during construction, and bodily injury to non-employees on the job site.
What it does not cover: Claims that arise after the sub's work is complete. Once the sub has finished their scope and left the project, the CG 20 10 endorsement provides no coverage.
Verification requirements: The endorsement should be issued by the insurer and attached to the policy. The COI checkbox is not the endorsement. To verify, request a copy of the actual endorsement page - not just the COI.
CG 20 37: Completed Operations Coverage
The ISO CG 20 37 endorsement adds the GC as an additional insured for liability arising from the sub's completed operations. This is the endorsement that protects the GC from construction defect claims, post-completion structural failures, and other losses that arise after the sub's work is done.
Why this matters more than most GCs realize: Construction defect litigation is almost entirely a completed operations claim. In jurisdictions with 10-year statutes of repose, a roofing sub who finishes work on a project today may be the subject of litigation a decade from now. The GC will be named in that litigation. If the CG 20 37 endorsement isn't in place - and isn't maintained - the GC defends alone.
Duration requirements: The completed operations endorsement must remain in force for the GC's full exposure period. Best practice is to specify in the subcontract that the CG 20 37 coverage must be maintained for the duration of the applicable statute of repose in the project state, and to require evidence of renewal annually.
The practical enforcement problem: Tracking completed operations coverage five or eight years after project completion is difficult. Many compliance programs simply don't do it. This is a significant gap.
Comparing CG 20 10 and CG 20 37
| Feature | CG 20 10 | CG 20 37 |
|---|---|---|
| Coverage trigger | Ongoing operations | Completed operations |
| When coverage applies | While sub is working | After sub's work is complete |
| Primary risk addressed | Job site liability | Construction defect, post-completion failures |
| Duration needed | Project construction period | Duration of statute of repose |
| Most commonly missing | Rarely missing | Frequently missing |
| Most commonly checked on COI | Yes | Sometimes |
| Actual endorsement verification required | Yes | Yes |
Most subcontracts that require AI coverage require both forms. Many subcontractors provide only CG 20 10 because that is what their broker defaults to. The compliance gap is almost always in the completed operations endorsement.
How to Verify Actual AI Status
The ACORD 25 checkbox is your starting point. Here is the full verification sequence:
Step 1: Check the AI box on the COI. If it's not checked, you have nothing - stop and request a corrected COI.
Step 2: Look at the description of operations box. Does it list specific endorsement form numbers (CG 20 10, CG 20 37)? Does it name the GC entity specifically, or does it say "as required by written contract"?
Step 3: For high-value subcontracts and trades with significant completed operations exposure, request the actual endorsement pages from the sub's broker. The endorsement page will show: the form number, the edition date, the named insured, and the additional insured entity.
Step 4: Compare the AI entity on the endorsement to the GC's correct legal name. Not a DBA. Not a parent company. The exact legal entity that signed the subcontract.
Step 5: If the endorsement uses "blanket additional insured" language, read the blanket endorsement carefully. Many blanket AI endorsements require a written contract as a prerequisite - confirm the executed subcontract satisfies that requirement.
Blanket vs. Scheduled Additional Insured Endorsements
Scheduled AI endorsement: Names the additional insured specifically by entity name. More targeted, less ambiguous, but requires the broker to update the endorsement when contracts change.
Blanket AI endorsement: Covers any party that requires AI status by written contract. More flexible for subcontractors with many GC relationships, but the scope of coverage depends on whether a qualifying written contract exists.
Both can be acceptable, but blanket endorsements require you to confirm that the qualifying written contract language is in place and that the blanket endorsement form doesn't contain restrictions that limit coverage in ways your contract doesn't anticipate.
Downstream AI Requirements: Sub-Sub Chains
Large construction projects involve multiple tiers of subcontractors. The concrete GC subs to a concrete framing company that uses three specialty sub-subs for post-tension work. The electrical GC subs to a specialty panel installer. Each layer creates additional AI exposure.
Your subcontract should require that first-tier subs flow AI requirements down to their own subcontractors and name you (the prime GC) as an additional insured on sub-sub policies as well. This requirement is common. It is rarely enforced because the documentation chain is difficult to manage.
If a sub-sub causes an injury and the prime GC is named in the lawsuit, the GC needs AI coverage on the sub-sub's policy - not just the first-tier sub's policy. Build this into your subcontract flow-down requirements and add documentation requirements for sub-sub COIs on projects above a threshold contract value.
What Happens When the AI Endorsement Is Missing
When a claim arises and the AI endorsement is absent, deficient, or covers the wrong scope:
- The sub's insurer denies defense and indemnity for the GC
- The GC's own GL or umbrella policy responds (if applicable)
- The GC's insurer may subrogate against the sub (if no WOS is in place)
- The GC may have a breach of contract claim against the sub, but litigation to recover insurance proceeds is expensive and uncertain
The downstream costs - increased GC insurance premiums, self-insured retention payments, defense costs for uncovered claims - often exceed the savings from relaxed compliance enforcement. The math strongly favors rigorous AI verification.
Bramble automates the AI verification step by reading the subcontract requirements and comparing them against the COI and endorsement data. Every gap - missing CG 20 37, wrong entity name, blanket endorsement without a qualifying contract - is flagged automatically before the sub starts work, not after a claim arises. See how it works for construction AI compliance.