Design-Build Insurance, Warranties and Consultant Liability: What Owners Should Check
Updated: Sep 20
Most owners ask about price and schedule first. The questions that decide what happens when something goes wrong come later, and usually too late. Design-build insurance, warranty coverage and consultant liability are the three that matter, and they behave differently under design-build than they do under a traditional design-bid-build contract.
The good news is that the design-build model concentrates responsibility rather than spreading it. The catch is that concentrated responsibility is only worth anything if the party holding it is actually insured for it. Here is what to check.
Why design-build insurance works differently
Under a traditional arrangement you hold two contracts. Your architect and engineers carry professional liability, commonly called errors and omissions, for the design. Your contractor carries commercial general liability for the construction. If something fails, the argument about which of the two caused it is your argument to referee.
Under design-build, one entity is responsible for both. That is the entire point. It also means that entity must carry both kinds of coverage, and you need to confirm which policy would actually respond.
Commercial general liability covers damage, not design
A commercial general liability policy responds to bodily injury and property damage. It typically does not respond to pure financial loss caused by a design error. If a system is designed incorrectly, installed exactly as designed, and then simply does not perform, there may be no bodily injury and no physical damage to third-party property, only a building that does not work and an owner losing money. That is precisely the gap a general liability policy is not built to fill.
Professional liability is the policy that answers a design error
Errors and omissions coverage responds to a failure to meet the professional standard of care in design. Under design-build, this can sit in two places: with the design consultants engaged by the design-builder, and with the design-builder itself under a contractor professional liability or design-build professional liability policy. The second one matters because your contract is with the design-builder, not with their consultants.
Who actually carries the design-build insurance
Ask the question plainly and get the answer in writing. Does the design-builder carry its own professional liability, or is it relying entirely on its consultants carrying theirs? What are the limits, and are they per claim or in the aggregate for the policy year? Is the policy project-specific or does your project share a limit with every other job the firm is running? A generous-looking limit shared across a dozen projects is not the protection it appears to be.
Four things to confirm before you sign
Certificates of insurance naming the actual entities. Not the parent company, not an affiliate, the entity signing your contract.
Limits appropriate to the project. The right question is not whether the limit is large, but whether it is large relative to what a failure of this building would cost to fix.
Claims-made versus occurrence, and the tail. Professional liability is usually written on a claims-made basis. If the policy lapses after the project closes, coverage can disappear at exactly the moment a latent problem appears. Ask how long coverage will be maintained after substantial performance.
Who buys the course of construction and property coverage. Builders risk, delayed opening or soft costs coverage, and who is named. Get this settled before mobilisation, not after a fire.
Warranties: what one year actually means
The general warranty period
Standard Canadian construction contracts carry a general warranty, commonly one year from substantial performance, during which the contractor corrects defects in work and materials. Owners routinely mistake this for a guarantee that the building will be perfect for a year and then the clock stops. It is neither of those things.
Extended and manufacturer warranties are separate
Roofing, glazing, mechanical equipment, elevators and specialty systems often carry longer manufacturer warranties, sometimes ten or twenty years, with conditions attached. Those conditions are where owners lose coverage: a required maintenance regime, approved service providers, documented inspections. Ask for the warranty documents at closeout, not the summary, and read the maintenance obligations.
Latent defects outlive the warranty
A warranty period is a contractual repair obligation. It is not a limitation period. A defect that could not reasonably have been discovered during the warranty period may still be actionable afterwards, subject to the limitation periods that apply in your province. In Ontario there is both a basic limitation period running from discoverability and an ultimate limitation period. Getting advice on your own situation matters here, because these timelines move quickly once someone knew or ought to have known.
Consultant liability when the consultant works for the builder
Novated design and what you give up
A common design-build structure has the owner engage a design consultant to prepare early concept work, and then novate that consultant to the design-builder. It is efficient. It also means the consultant who set your design intent now answers to the party building it, and your direct contractual relationship is gone. If the design later proves inadequate, your claim runs through the design-builder.
Reliance letters keep a door open
Where the design-builder engages the consultants, owners often ask for reliance letters or a direct duty of care agreement so that the owner has some recourse against the designer if the design-builder becomes insolvent. That last scenario is not hypothetical, and it is the main reason experienced owners ask for it.
Your own advisor is not a luxury
Owner engineers, payment certifiers, commissioning agents and building envelope consultants work for you and only for you. On a design-build project, where the design-builder is checking its own homework, an independent set of eyes at the right milestones is the cheapest insurance in the stack.
A practical owner checklist
Get all certificates of insurance before mobilisation and diarise their renewal dates.
Confirm whether professional liability is project-specific or shared, and for how long it will be maintained.
Agree in writing what happens to consultant obligations if the design-builder defaults.
Require a closeout package that includes warranties, maintenance requirements, as-built documentation and commissioning records.
Diarise the end of the general warranty period and walk the building sixty days before it expires, not sixty days after.
Have your own construction counsel and your own broker read the insurance and indemnity provisions before signing.
The honest summary
Design-build genuinely simplifies accountability. It does not automatically improve your protection. The value of a single point of responsibility depends entirely on the financial strength and the insurance behind that single point, and on a closeout process that leaves you with documents rather than promises. Those are questions to ask while you still have leverage, which is to say before you sign.
Common questions about design-build insurance and warranties
Does a design-builder’s general liability policy cover design errors?
No. A commercial general liability policy responds to bodily injury and property damage. Design errors fall under professional liability, or errors and omissions, which is a separate policy. Ask plainly whether the design-builder carries its own, and get the answer in writing.
How long is the warranty on a design-build project?
Standard Canadian contracts carry a general warranty of commonly one year from substantial performance. Roofing, glazing, mechanical equipment, elevators and specialty systems often carry longer manufacturer warranties. A warranty period is a contractual repair obligation, not a limitation period.
What insurance documents should I ask for?
Certificates naming the entity actually signing your contract rather than a parent or an affiliate, limits sized against the risk rather than simply large, confirmation of whether professional liability is claims-made and what tail is maintained, and clarity on who buys builders risk and soft costs coverage.
What is novation in a design-build contract?
It is where you engage a design consultant for early concept work and then transfer that consultant across to the design-builder. It is common and workable, but the terms of the transfer decide who you can look to later, so they are worth reading before you sign.
If you are evaluating a delivery model or a project team, that review is a conversation worth having early. You can see how I work with owners and project partners on project solutions.
This article is general information about commercial construction practice in Canada. It is not legal or insurance advice, and I am not a lawyer or a broker. Have your own counsel and your own insurance advisor review your contract and your coverage.
Connect with Carolee on LinkedIn: linkedin.com/in/carolee-w-turner-2002417
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