ISO CG 20 01 Primary & Noncontributory + CG 24 04 Waiver of Subrogation: Preventing Horizontal Exhaustion
When a serious $2,500,000 claim occurs on a project where a subcontractor or vendor carries $1,000,000 Primary GL and $5,000,000 Excess/Umbrella, upstream GCs and Owners expect the subcontractor’s $1M Primary and $5M Umbrella to pay the full $2.5M ("Vertical Exhaustion"). However, if ISO CG 20 01 ("Primary and Noncontributory — Other Insurance Condition") is missing, or if the subcontractor’s Umbrella policy contains a standard "Excess Over All Other Valid and Collectible Insurance" clause, courts enforce "Horizontal Exhaustion"—forcing the upstream GC’s and Owner’s own primary GL policies to pay before the subcontractor’s Umbrella contributes a dollar.
General Contractor Left With $320,000 Uninsured Water Defect Claim Due to Missing CG 20 37 & CG 22 94 Exclusion
A GC collected a subcontractor COI showing "Additional Insured: Yes," but the actual binder only attached ISO CG 20 10 (Ongoing Operations)—omitting ISO CG 20 37 (Completed Operations)—and the GC’s own GL policy contained ISO CG 22 94 deleting the Subcontractor Exception.
EndorseIQ™ mandates both ISO CG 20 10/20 38 and CG 20 37 (Completed Operations), strikes ISO CG 22 94 and CG 21 39, and enforces Primary & Noncontributory (CG 20 01) vertical exhaustion.
Check Your Full Contract PDF for Cross-Section Overrides (Free 60s Scan)
Fixing one clause alone often fails when a buried definition, exhibit, or survival clause elsewhere in your Construction GL & Subcontractor neutralizes your protection. Drop your PDF or Word (.docx) below for an instant, 100% anonymous cross-section audit.
“PRIMARY & NONCONTRIBUTORY VERTICAL EXHAUSTION (ISO CG 20 01 + UMBRELLA FOLLOW-FORM) & BLANKET WAIVER OF SUBROGATION (ISO CG 24 04): (a) Primary CGL policy includes ISO Endorsement CG 20 01 (Primary and Noncontributory); (b) Excess/Umbrella policy is endorsed to respond on a strictly Primary and Noncontributory Vertical Exhaustion basis immediately above the subcontractor’s Primary CGL and ahead of any primary or
What to Say to the GL Carrier & Upstream GC / Owner Requirements
"Checking Primary & Noncontributory on the ACORD 25 COI only addresses the first $1M Primary GL layer unless the $5M Umbrella is also endorsed for Vertical Exhaustion. We need ISO CG 20 01 on the Primary, a Primary & Noncontributory Priority of Coverage endorsement on the Umbrella, Blanket CG 24 04 Waiver of Subrogation, and CG 25 03 Per-Project Aggregate."
Why they drafted it this way: Umbrella carriers intentionally write strict Other Insurance clauses so they can shift the second million dollars of a catastrophic loss onto the upstream General Contractor’s or Building Owner’s primary insurer.
Mandatory Audit Checklist Points
- Attach ISO CG 20 01 (Primary and Noncontributory) to the Primary Commercial General Liability policy
- Endorse the Excess/Umbrella policy for Vertical Exhaustion so it drops down before upstream primary policies
- Bind Blanket Waiver of Subrogation on GL (CG 24 04), Business Auto (CA 04 44), and Workers’ Comp (WC 00 03 13)
- Attach ISO CG 25 03 (Designated Construction Project General Aggregate Limit) to prevent aggregate erosion
Paste Your ISO CG 20 01 Primary and Noncontributory CG 24 04 Waiver of Subrogation vertical exhaustion Section or Upload Your Full Construction GL & Subcontractor (.pdf / .docx)
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EndorseIQ™ Policy & Binder Scanner
ACTIVE ENGINE: ENDORSEIQ™ (MULTI-HOP ISO & COVERAGE GRAPH)Frequently Asked Questions
Why does ISO CG 20 01 require a written contract specifying Primary and Noncontributory status?
ISO Form CG 20 01 modifies the Other Insurance condition ONLY when you have agreed in writing in a contract or agreement that this insurance would be primary and would not seek contribution from any other insurance available to the Additional Insured. If the underlying subcontract forgets the words "and noncontributory," CG 20 01 will not trigger.
What is the difference between ISO CG 24 04 and ISO CG 29 88?
ISO CG 24 04 is the standard Waiver of Transfer of Rights of Recovery Against Others to Us (Waiver of Subrogation), which can be scheduled or written on a blanket contractual basis. ISO CG 29 88 is the newer Automatic Blanket Waiver of Subrogation when required by written contract.
How do I redline ISO CG 20 01 Primary and Noncontributory CG 24 04 Waiver of Subrogation vertical exhaustion traps in my Construction GL & Subcontractor anonymously without creating an account?
Upload your Construction GL & Subcontractor PDF or Word (.docx) draft to ExclusionRadar.com to run the "ISO CG 20 01 Primary & Noncontributory + CG 24 04 Waiver of Subrogation: Preventing Horizontal Exhaustion" defense cartridge 100% anonymously—with zero account registration, zero email login, and stateless in-memory processing. EndorseIQ™ flags ISO CG 20 01 Primary and Noncontributory CG 24 04 Waiver of Subrogation vertical exhaustion exposure (typically $75,000 – $500,000+ in Horizontal Exhaustion & carrier subrogation claims; documented unredlined loss: $320,000 denied Completed Operations & subcontractor defect claim), checks for cross-section overrides, and exports a ready-to-send Microsoft Word (.docx) Track-Changes file.
More Construction GL & Subcontractor Redline Playbooks
View All Construction GL & Subcontractor PlaybooksISO CG 25 03 Designated Construction Project Aggregate Audit: Preventing Off-Site Limit Erosion
Without ISO Endorsement CG 25 03 ("Designated Construction Project(s) General Aggregate Limit"), a contractor’s $2,000,000 General Aggregate Limit is shared across EVERY jobsite the contractor worked on during the entire year. If a subcontractor you hired suffers a $1.8M claim on an unrelated job across town in March, only $200,000 of aggregate coverage remains for your project in July! Furthermore, even when carriers attach CG 25 03, they often layer a manuscript "$5,000,000 Policy-Wide Aggregate Cap" on top.
Multi-Family, Condominium & Tract Housing Exclusion Audit: Catching Mixed-Use GL Coverage Traps
Nearly every non-admitted construction GL policy contains a manuscript "Residential / Habitational / Condominium / Tract Housing Exclusion." While contractors working on ground-floor retail storefronts, commercial offices, or apartment renovations assume this exclusion only applies to single-family homebuilders, carriers draft these endorsements to exclude ANY work on a structure that contains—or is ever converted into—residential apartments, condominiums, townhomes, student housing, or mixed-use retail/residential buildings!
Earth Movement, Subsidence, EIFS (CG 22 91) & Mold/Fungi (CG 21 67) GL Exclusion Audit
Surplus-lines construction GL binders frequently bundle three silent defect exclusions that destroy coverage for site-work, plumbing, and exterior envelope contractors: (1) an "Earth Movement / Subsidence / Soil Settlement Exclusion" that bars any foundation crack, trench collapse, or retaining-wall claim even when caused by human excavation or a burst pipe; (2) ISO CG 22 91 ("Exclusion — Exterior Insulation and Finish Systems / EIFS"), which excludes any property damage to a building if synthetic stucco/EIFS exists anywhere on the exterior; and (3) ISO CG 21 67 ("Fungi or Bacteria Exclusion"), which denies water-leak claims the moment a plaintiff’s complaint mentions mold.
Subcontractor Warranty Endorsement Audit: Avoiding 100% Claim Denials & $50,000 Deductible Penalties
In addition to ISO forms, non-admitted construction GL carriers attach a manuscript "Independent Contractors / Subcontractor Warranty Endorsement" (Condition Precedent). This clause states that the GC has ZERO coverage for any claim involving a subcontractor unless, prior to the sub setting foot on site, the GC obtained: (1) a signed written hold-harmless contract, (2) Additional Insured endorsements CG 20 10 + CG 20 37, (3) Primary & Noncontributory status, and (4) matching $1M/$2M GL limits. If a single day-laborer or emergency repair sub has an expired COI or missing CG 20 37, the GC’s own GL policy voids coverage completely!