CG 20 37 is the standard ISO endorsement — formally the Additional Insured – Owners, Lessees or Contractors – Completed Operations form — that names a general contractor or project owner as an additional insured on your general liability policy for your completed work. It is the completed-operations companion to CG 20 10, the ongoing-operations version, and the difference between the two is the whole reason a general contractor requires CG 20 37 from an HVAC subcontractor. This post explains what the form does, how it differs from CG 20 10, and what to confirm before you hand over a certificate.
The short version: CG 20 10 protects the GC while your crew is on the job; CG 20 37 protects the GC after the job is done. For HVAC, where the install can fail long after the project closes, that second timeframe is the one the general contractor actually cares about. The full treatment of how additional-insured status fits the trade lives on our general liability page; this post stays on the single form that confuses contractors most at certificate time.
What CG 20 37 actually does
An additional-insured endorsement adds another party — here, a general contractor or building owner — to your liability policy as an insured for claims arising out of your work. CG 20 37 does that specifically for the products-completed-operations hazard: the third-party bodily injury and property damage your finished work causes after the job is complete and away from the site. When a GC is named on CG 20 37, the GC’s own defense and indemnity for a completed-operations claim tied to your work can draw on your policy, not just its own.
That is a real, named ISO form, not something a carrier invents per account, and it is the form commercial contracts reference by number. It works alongside the completed-operations coverage you already carry for yourself — the products-completed-operations hazard of your standard CGL — rather than replacing it. The endorsement is the contractual layer; your underlying coverage is what it extends to the GC.
CG 20 37 versus CG 20 10: the timeframe that matters
The two forms look almost identical on a certificate and cover opposite ends of the job. CG 20 10 — Additional Insured – Owners, Lessees or Contractors – Ongoing Operations — names the GC for your ongoing operations: the work while it is in progress, the crew on site, the job not yet finished. CG 20 37 names the GC for your completed operations: the finished work, after the crew has left, once the project is closed.
For most trades that distinction is a technicality. For HVAC it is the entire exposure. An HVAC system runs for years after the install, and the losses that define the trade — a fire traced to the work, a carbon-monoxide claim from a flue or heat-exchanger fault, water damage from a failed condensate line — surface during the completed-operations period, not while the crew is still on the job. A general contractor named only on CG 20 10 loses its additional-insured status right at substantial completion, the moment before the tail risk begins. That is why an ongoing-operations endorsement does not satisfy a completed-operations requirement, and why a contract that means CG 20 37 will not accept CG 20 10 in its place.
Why the completed-operations tail is the GC’s real worry
A general contractor that hires you is not only managing today’s job site; it is managing the building it hands over. If your install fails two years on and a third party is hurt or property is damaged, the claim can reach back to the GC and the owner as well as to you. They want their own additional-insured protection to be live during that period, on your policy, which is precisely what CG 20 37 provides. Naming them only on CG 20 10 would protect them for the on-site phase and then drop them at the exact moment the HVAC exposure matures.
This is the same completed-operations logic that governs your own coverage. Standard general liability is written on an occurrence basis and responds to a claim based on when the damage happened, so the policy in force during the install answers that install’s later claims — for you, and for the GC named on CG 20 37 at the time. That is why continuity matters on both sides: the endorsement is only as good as the underlying coverage it sits on, and a lapse undercuts the completed-operations grant the contract relied on. The mechanics of the occurrence trigger and the products-completed-operations hazard are covered in full in does general liability cover completed operations for HVAC and what is completed operations coverage for HVAC.
How to read the requirement on your contract
Most HVAC subcontractors meet CG 20 37 at the certificate-of-insurance stage, when a general contractor’s insurance requirements come down before the job starts. Those requirements name the additional-insured endorsements by number and often by edition date. The bundle of certificate requirements a GC typically asks for is its own topic, covered in what insurance do general contractors require from HVAC subs; the point here is the one form that trips people up.
How to check your own policy
The CG 20 37 question turns into a short list to confirm before you sign or hand over a certificate — the actionable part of this post:
- Read the contract for the exact form and edition. A completed-operations requirement names CG 20 37, sometimes with a specific edition date. Match the number and the edition rather than assuming the additional-insured form already on your policy satisfies it.
- Confirm CG 20 37, not just CG 20 10, is attached. A policy can carry the ongoing-operations endorsement and not the completed-operations one. If the contract calls for completed operations, the ongoing-operations form alone does not meet it.
- Confirm your underlying completed operations is intact. CG 20 37 extends your products-completed-operations coverage to the GC, so verify that coverage is granted and not excluded on your own form first.
- Mind the edition language. Editions differ in scope and how they handle limits. Have your agent confirm the policy can attach the exact form and edition the contract names.
Because wording, forms, and editions vary by carrier and project, confirm the exact form and edition the contract calls for — a generic additional-insured form may not satisfy a completed-operations requirement, and finding that out at certificate review is far better than finding it out at claim time.
Where CG 20 37 fits in the program
CG 20 37 is a contractual extension of your general liability, not a standalone coverage, and it is one piece of qualifying for commercial HVAC work — though the same certificate discipline carries over to residential HVAC work on larger accounts. Carry general liability with completed operations confirmed and its aggregate set to your install volume, keep the policy continuous so the occurrence trigger and the additional-insured grant both hold, and when a contract names CG 20 37, meet it on the right form and edition. When you are ready, start a quote, read the full general liability treatment to see how additional-insured status sits in the policy, or step back to what drives HVAC insurance costs to see where the commercial requirements fit in the program.