An additional insured (AI) endorsement modifies your general liability policy to extend coverage to a third party — typically a general contractor, property owner, or developer — for liability arising out of your work. It does not give them coverage for their own negligence (in most forms); it protects them from claims caused by your operations or your completed work. For roofing contractors, understanding and carrying the correct AI endorsements is essential because GCs will not sign your subcontract without them.
The Two Key Endorsement Forms
The construction industry has standardized around two ISO endorsement forms that you will encounter on virtually every commercial roofing project:
CG 20 10 — Additional Insured, Owners, Lessees or Contractors, Scheduled Person or Organization. This endorsement covers the additional insured for liability arising out of your ongoing operations — meaning work you are currently performing on the jobsite. If your crew drops debris on a bystander and the GC is sued, CG 20 10 allows the GC to tender the claim to your GL policy.
CG 20 37 — Additional Insured, Owners, Lessees or Contractors, Completed Operations. This endorsement extends additional insured status to the same party for claims arising out of your completed work. If a roof you installed leaks two years later and damages interior property, and the property owner sues both you and the GC, CG 20 37 allows the GC to tender the completed operations claim to your GL policy.
Most subcontracts require both CG 20 10 and CG 20 37 — ongoing operations and completed operations. Providing only CG 20 10 without CG 20 37 is one of the most common certificate deficiencies that delays roofing projects. Some carriers offer a combined form, CG 20 26, that covers both ongoing and completed operations in a single endorsement.
Blanket vs. Scheduled Endorsements
AI endorsements come in two structures. A scheduled endorsement lists the specific additional insured by name. Every time you take on a new GC or project, your agent must add the new party to the endorsement. This creates delays and administrative overhead.
A blanket endorsement (sometimes called "automatic" additional insured) extends AI status to any party you are required to name as an additional insured by written contract. As long as a written subcontract requires AI status, the endorsement applies automatically — no need to schedule the party individually. Blanket AI endorsements eliminate certificate delays and are strongly preferred for roofing contractors who work with multiple GCs throughout the year.
Primary and Non-Contributory
Many subcontracts require that your GL be "primary and non-contributory" with respect to the additional insured. This means your policy pays first, before the additional insured's own GL policy, and your policy does not seek contribution from their policy. Without this language, the two policies might share the claim on a pro-rata or equal basis, which is not what the GC wants. The ISO endorsement CG 20 01 provides primary and non-contributory status, or your carrier may include this language in their blanket AI endorsement.
Cost and Availability
Blanket additional insured endorsements typically add $200 to $800 per year to your GL premium. Scheduled endorsements may carry a per-endorsement fee of $25 to $75 each. Some carriers include blanket AI at no additional charge as part of their contractor's coverage package. Given that the endorsement is required for virtually every commercial project, the cost is negligible compared to the revenue it protects.
Common Mistakes
The most frequent mistake is assuming your policy automatically includes AI coverage. Standard GL policies do not — the endorsement must be added. The second mistake is providing CG 20 10 (ongoing operations) but not CG 20 37 (completed operations). GCs increasingly require both, and the completed operations exposure is where the largest claims occur. Third, failing to confirm that your umbrella policy extends AI status to the same parties covered under your GL leaves a gap in excess coverage. Fourth, using an outdated endorsement edition — some GCs specify the edition date (e.g., CG 20 10 04 13) and will reject earlier editions with narrower coverage language.
Work with an agent who places your GL with a carrier offering current-edition blanket AI endorsements covering both ongoing and completed operations, with primary and non-contributory language included. This eliminates the most common certificate deficiencies and keeps your projects moving.