When you work as a sub, a general contractor’s contract will require you to add it as an additional insured on your general liability — and for a concrete contractor that usually means two endorsements, not one. One covers the general contractor while your crews are on the job; the other covers it after your concrete work is finished. Getting both right is what keeps an insurance requirement from stalling the job.
This post explains what additional-insured status actually does, which two endorsements a general contractor will require and how they are named, why concrete’s long tail makes the second one the piece that gets missed, and how blanket wording differs from scheduling each party by name. The short version: your finished installation is “your work,” and a careful general contractor wants to be protected both while you build it and after you leave.
What additional-insured status actually does
Additional-insured status extends part of your general liability protection to another party for liability connected to your work. When you sub under a general contractor, its contract almost always requires it — the general contractor wants to be able to reach your policy if a claim arising from your operation names them, too. It does not make the general contractor a named insured on your entire policy, and it does not cover their own separate mistakes; it adds them for the specific exposure your concrete work creates.
For a concrete installation contractor, this is one of the first things a contract will demand, and it is non-negotiable on most commercial jobs. The general contractor will not let you mobilize without a certificate showing the status it requires. So the endorsements are not paperwork — they are the thing that lets you on the site.
The two endorsements a general contractor will require
In ISO’s system, additional-insured status for a general contractor is typically handled with two endorsements added over the standard commercial general liability form — usually the occurrence version known as CG 00 01. A well-drafted contract usually requires both:
- CG 20 10 — ongoing operations. Adds the general contractor (or project owner) as an additional insured for your ongoing operations, the protection they want for the duration of the work while your crews are on site.
- CG 20 37 — completed operations. Extends that additional-insured status to your completed operations, the protection the general contractor wants after your concrete work is finished.
The exact edition and form language vary by carrier, so the honest instruction is to confirm which endorsements are actually attached to your policy rather than assume the pair is there. Naming them is useful precisely because it hands you a check to run against your own declarations page.
Why a general contractor requires both, not just one
The reason the pair matters comes straight from the nature of concrete work. CG 20 10 protects the general contractor while your crews are on site, but it can leave them without additional-insured status once you have wrapped up and gone. And the completed-operations tail is precisely when a concrete claim tends to surface — a slab, footer, or foundation you placed that fails downstream, after the job is done.
That is the gap CG 20 37 closes. It extends additional-insured status to your completed operations, so the general contractor is still protected for liability connected to your finished work after your crews have left. A general contractor that understands concrete knows to ask for both, because the exposure it most wants covered on a concrete sub is the one that shows up late. Requiring only the ongoing-operations endorsement protects the general contractor during the weeks you are on site and leaves it exposed during the years afterward, which is backwards for this trade.
Real-World Scenario: A concrete sub pours the foundations and flatwork on a commercial building and demobilizes when the job wraps. More than a year later a section of slab fails, and the resulting property-damage claim names both the sub and the general contractor. Because the sub’s policy carried the completed-operations additional-insured endorsement the contract required, the general contractor had the status it bargained for on the finished work — not just for the weeks the crews were on site. Had the sub added only the ongoing-operations endorsement, the general contractor’s additional-insured status would have run out the day the crew drove away, right before the exposure it cared about actually surfaced.
Blanket versus scheduled additional insured
There are two ways a policy grants additional-insured status, and the difference is practical. Scheduled coverage lists each party by name on the endorsement — every general contractor added one at a time. Blanket coverage grants the status automatically to any party you have agreed in a written contract to add, without naming each one.
For a concrete contractor bidding job after job, blanket wording is usually far more workable than scheduling every general contractor separately, because certificate requests arrive constantly and scheduling each one by hand is slow and easy to miss. But whether your policy actually carries blanket wording — and whether that blanket wording includes the completed-operations endorsement, not just ongoing operations — depends on the endorsements attached to your specific policy. Terms and forms vary by carrier, so this is another place to read rather than assume the coverage is broad.
”Where a written contract requires”
Blanket endorsements typically grant additional-insured status only “where a written contract requires” it — which puts the written contract itself at the center of the coverage. Rather than the endorsement naming who is covered, the contract you sign controls who gets added and how far the status reaches. That is a subtle but important point: the document you agree to with a general contractor is what drives the coverage the endorsement provides.
It is also why reading a general contractor’s insurance requirements against your own endorsements before you sign is worth the time. If the contract demands completed-operations additional-insured status at a certain limit and your policy carries only ongoing-operations status, you want to find that out at the bid, not when a certificate request lands on your desk mid-job.
What additional-insured status does not do
Additional-insured status is about who else your general liability protects — not about widening what general liability covers for you. It does not extend coverage to your own crew: injuries to your workers run through workers compensation, a separate line. And it does not touch your vehicles — a boom pump truck and a ready-mix mixer fleet are covered under commercial auto, which answers auto liability and physical damage on the trucks themselves. Additional-insured endorsements add a general contractor to your general liability for liability connected to your work; they do not turn general liability into a policy that also answers your crew or your trucks.
Get the endorsements right before the certificate request
The takeaway is straightforward: for a concrete contractor working under general contractors, additional-insured status usually takes two endorsements — one for ongoing operations while you build the work, one for completed operations after you leave — and the completed-operations piece is the one that gets missed on a policy bought on price. Confirm both are attached, check whether your status is blanket or scheduled, and read your contracts against your endorsements before you sign. Coverage depends on the specific policy and its endorsements, and how the trigger is written matters too, so it is worth walking through occurrence versus claims-made alongside the additional-insured question. When you are ready, start a quote and send us the contracts you are bidding, read the full general liability page, or browse the coverage overview to see where each line sits.