Pen-and-ink street scene: a plumbing van with its back doors open and pipe on the roof rack outside a house, a commercial building in scaffolding with exposed pipe across the road.

Certificates and additional insureds for plumbers

a certificate
shows coverage.
it doesn’t change it.

What each document does when the GC asks for a COI.

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the short answer

A certificate of insurance is a snapshot of the policies you carry on the day it’s issued. It doesn’t add coverage or make anyone an additional insured on its own. An endorsement on the policy does that, so a GC asking for a COI naming them is asking for both.

the words, in plain English.

What each piece of a GC’s insurance request means.

Certificate of insurance: A one-page summary of your policies and limits on the day it’s issued. The standard ACORD form says it confers no rights and doesn’t amend the policy.
Certificate holder: Who the certificate is addressed to, usually the GC or owner, by exact legal name and address. Being the holder doesn’t make them an additional insured.
Additional insured: An endorsement that extends your general liability to the GC for claims from your work. CG 20 10 covers ongoing work. CG 20 37 covers completed work.
Waiver of subrogation: An endorsement that gives up your carrier’s right to recover from the GC after it pays a claim. Per project or blanket, and sometimes priced.
Primary and noncontributory: Wording that says your policy pays first and doesn’t ask the GC’s policy to share the loss. It’s an endorsement, not a line on the certificate.

Sources: ACORD certificate of liability insurance, ISO additional insured endorsements CG 20 10 and CG 20 37. Last reviewed September 2026.

tap a document.

Four documents, four different jobs. Only one changes what’s covered.

The document

the contract.

The insurance exhibit lists limits, additional insured status, waivers and wording. It’s the request, and it can’t change your policy by itself.

Who asks: The GC or owner, before the crew mobilizes.

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how to ask
so it comes back right.

Send the exhibit.
Send the contract’s insurance page, not a summary. It names the limits, endorsements and wording the certificate has to show.
Name every party.
List each certificate holder’s exact legal name and address, and say which ones also need additional insured status.
Send it with the bid.
The endorsements take the time. A certificate asked for the morning of mobilization is the one that holds up the job.

good to know.

Straight answers on certificates and additional insureds.

Does a certificate of insurance make the GC an additional insured?

No. The endorsement on the policy does. The certificate only shows that the endorsement exists, and the standard certificate form says so in its own fine print. When a GC asks for a certificate naming them as additional insured, the real work is getting the endorsement onto the policy. The certificate is the last step, and the easy one.

What is the difference between ongoing and completed operations?

Ongoing operations covers the GC for claims that come up while you’re still on the project, like a visitor who trips over staged pipe. Completed operations covers the GC for claims after you finish, like a joint that lets go above a finished ceiling a year later. They’re separate endorsements, and a contract that asks for both needs both on the policy.

Can I add a waiver of subrogation for one job?

Usually, yes. A waiver gives up your carrier’s right to recover from the GC after paying a claim. It can be written for one project, or as a blanket that applies wherever a written contract asks for it. It’s sometimes priced, and the one on workers’ comp is separate from the one on general liability. It has to be on the policy first.

Sources: ACORD certificate of liability insurance, ISO additional insured endorsements. Last reviewed September 2026.

Insurance words, in plain English: waiver of subrogation · certificate of insurance · additional insured · primary and noncontributory · hold harmless agreement · contractual liability · per-project aggregate · completed operations