Design-Build Liability: Why Separate GL and E&O Policies Leave a Gap

The design-build delivery model has grown steadily because it gives owners a single point of responsibility and often delivers projects faster. For the contractor, though, it creates an insurance problem: you're holding two types of liability under one contract, and most standard insurance programs weren't designed for that.

The Dual Exposure of Design-Build

In traditional delivery, the owner holds separate contracts with the designer (architect or engineer) and the contractor. Each carries their own liability. The designer carries professional liability (E&O) for the design. The contractor carries GL for the construction.

In design-build, you hold both. If something goes wrong — whether it's a design error, a construction defect, or a combination of both — the owner comes to you. One party. Full responsibility.

Your insurance program needs to reflect that reality.

Where Split Policies Fail

A design-build contractor who buys a standard GL policy from one carrier and a professional liability policy from another will almost inevitably face a coverage dispute at claim time.

Here's why:

The GL carrier will look to exclude professional services. When a claim involves a design decision — a specification, a design choice, a coordination decision made during development — the GL carrier invokes the professional services exclusion and denies the claim.

The E&O carrier will look to exclude physical damage. When the claim includes property damage resulting from the professional error, the E&O carrier may argue that the physical damage is a construction defect, not a professional services claim, and refer back to the GL.

The claim falls in the middle. The most common design-build claims — a design error that caused physical rework — span both policies. With separate carriers, that's where disputes happen. Two carriers, two sets of lawyers, one contractor caught between them.

What Design-Build Liability Insurance Does Differently

A design-build liability program is specifically structured to cover both the professional services exposure and the construction operations exposure in a coordinated way.

The key differences:

Single program, unified limits. Rather than having GL limits on one side and E&O limits on the other, a design-build program can be structured so a single large claim doesn't exhaust one policy and find the other suddenly relevant.

Coordinated exclusions. The professional liability and GL components are written to work together, so a claim that spans design and construction doesn't create an exclusion dispute between two separate carriers.

Appropriate for the delivery model. Design-build programs reflect the actual contractual structure — one contract, full responsibility — rather than forcing a delivery model built around integrated responsibility into policies designed for separated responsibility.

Subcontractor Design Exposure

Design-build contractors frequently rely on subcontractors — structural engineers, MEP designers, specialty consultants — for portions of the design.

As the design-build contractor, you're the party responsible for the whole. If a subcontractor's design error creates a claim, that claim may be directed at you even if the error wasn't yours.

Your professional liability should cover your exposure as the responsible coordinating party. Subcontractors should carry their own professional liability with you named as additional insured — but that coverage is secondary protection. Your design-build program is primary.

Who Needs Design-Build Liability

You need a coordinated design-build liability program if:

• You provide both design and construction under a single contract
• You have in-house design staff or employ engineers/architects
• You use design-assist subcontractors under your direction
• Your projects involve EPC (engineering, procurement, construction) delivery
• Your clients require you to hold both design and construction liability

If any of these apply, a split GL + E&O approach is a coverage risk, not a coverage solution.

Getting the Program Right

Design-build liability programs vary significantly in how the professional and construction liability components are structured, what exclusions apply, and what limits are appropriate for your project size.

The right program reflects your specific delivery model — the services you actually provide, the size of your projects, and the type of clients you work with. A standard GL quote won't do it.