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Commercial General Liability: Structure and Triggers
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A mid-sized general contractor based in the Calgary area held a commercial general liability policy with per-occurrence limits of $2 million and a general aggregate of $5 million when it secured the contract to construct a 4-storey mixed-use development in a nearby municipality. The project, valued at approximately $28 million, involved retail space on the ground floor, office space on the 2nd and 3rd floors, and 12 residential condominium units on the top floor. The development agreement required the general contractor to maintain CGL coverage naming the project owner and the construction lender as additional insureds, with primary and non-contributory status and a waiver of subrogation endorsement.

The general contractor subcontracted specialized work to several trades, including a mechanical subcontractor responsible for the building's HVAC and fire suppression systems and a waterproofing subcontractor engaged to apply protective coatings to the below-grade foundation walls and the rooftop membrane. The subcontracts required each trade to carry its own CGL coverage with minimum limits of $2 million per occurrence and to name the general contractor as an additional insured on their respective policies. The mechanical subcontractor's policy operated on an occurrence basis with a products and completed operations aggregate of $2 million. The waterproofing subcontractor's policy contained an exclusion for work performed by subcontractors of the named insured, though this subcontractor performed all work with its own employees.

Construction proceeded over 18 months. The waterproofing subcontractor completed its below-grade work during month 4 and its rooftop membrane application during month 14. The mechanical subcontractor finished installation of fire suppression equipment in month 16 and received final inspection approval. The general contractor achieved substantial completion in month 18, and the project owner took occupancy of the commercial spaces while the condominium units were marketed and sold to individual purchasers over the following 8 months.

Approximately 26 months after substantial completion, water infiltration became evident in 3 of the below-grade retail units. Remediation efforts revealed that the waterproofing membrane had failed at multiple seams, allowing groundwater to migrate through the foundation walls. During the same period, 2 condominium owners reported water damage to interior finishes, traced to failures in the rooftop membrane installation. Separately, a fire suppression head in one office suite activated without cause, flooding the space and damaging tenant improvements valued at over $180,000. The project owner, the condominium corporation, and the affected commercial tenant each advanced claims, naming the general contractor, the relevant subcontractors, and in some instances the project owner's own property insurer as potentially responsible parties.

The general contractor's broker requested coverage confirmation from the CGL insurer. The response raised questions about which policy year responded to the waterproofing failures, whether the products and completed operations coverage remained available given prior unrelated claims during the policy period, how defense costs would erode limits if multiple claimants proceeded simultaneously, and whether the additional insured endorsements extended the coverage the contractual counterparties believed they had secured.

Limits, Aggregates, and the Cost of Defense: How the Numbers Work

Commercial general liability insurance operates through a carefully constructed framework of numerical limitations that define the boundaries of coverage. Understanding how these limits function, how aggregates accumulate, and how defense costs interact with policy limits represents essential knowledge for any professional working with commercial insurance in Canada. The architecture of policy limits determines not merely the maximum amount an insurer will pay but also shapes how claims are handled, how multiple incidents across a policy period affect available coverage, and ultimately whether a policyholder faces personal or corporate exposure beyond their insurance protection. This lesson examines the mechanical operation of these numerical constructs, the legal principles governing their application, and the practical realities that emerge when limits are tested by actual claims.

The foundation of limit structures in commercial general liability policies rests on principles developed over decades of insurance practice and refined through both contractual evolution and judicial interpretation. Canadian courts have consistently held that policy limits represent the maximum contractual obligation of the insurer, not a guaranteed payment to any particular claimant. The Insurance Act in each province establishes the regulatory framework within which these limits operate, though the specific numerical values and structural arrangements remain matters of contract between insurer and insured. In Ontario, the Insurance Act governs the relationship between insurers and insureds, while British Columbia operates under its Insurance Act with parallel provisions, and Alberta follows similar common law principles under the Alberta Insurance Act. Quebec presents a distinct framework under the Civil Code of Quebec, where insurance contracts are governed by articles 2389 through 2628, though the fundamental economic operation of limits functions similarly despite the different legal foundation. As of the date of authorship, these provincial frameworks share the common characteristic of enforcing policy limits as stated in the contract while imposing certain minimum requirements for specific coverages, particularly in automobile liability contexts.

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