Construction Defect Claims in Ontario: Construction Act, ODACC Adjudication & Structural Engineering Evidence

Types of Construction Defects in Ontario

Construction defects fall into four categories relevant to structural engineering involvement:

• Design defects: Errors or omissions in the structural engineer's or architect's design — under-designed members, inadequate connection details, failure to account for code-required loads. These create professional liability exposure for the design professional.
• Materials defects: Sub-standard, defective, or incorrectly specified materials — out-of-spec concrete (low strength), degraded rebar, improper lumber grade, defective steel. May be a contractor's responsibility, supplier's responsibility, or a materials testing deficiency.
• Construction (workmanship) defects: Failure to build in conformance with design documents — incorrect member sizing, missing reinforcement, deficient connections, inadequate weld quality, improper grouting or fire-stopping. Most common structural defect category in new construction.
• Subsurface/geotechnical defects: Foundation settlement, slope instability, or soil movement resulting from inadequate geotechnical investigation or failure to follow geotechnical recommendations.

Ontario Construction Act 2018 Overview

Ontario's Construction Act (formerly the Construction Lien Act), substantially amended by Bill 142 in 2017 and effective for most contracts from October 2019, governs the rights of parties on Ontario construction projects including:

• Definition of substantial performance: The Construction Act defines when a contract is substantially performed — triggering holdback release deadlines and the start of lien periods. Dispute about whether substantial performance has been achieved often arises in defect situations where the owner argues defects prevent substantial performance.
• Lien rights for contractors: Contractors, subcontractors, and suppliers have lien rights against the improved property for unpaid amounts under the Construction Act. A structural engineer who believes they have a defect-related claim against the contractor can register a claim for lien if unpaid.
• Holdback requirements: Owners are required to retain a 10% statutory holdback from each payment to contractors. Holdback cannot be released while there are unsatisfied liens or during a defined period after substantial performance notice. The holdback serves as a fund against which defect-related claims can be made.

Tarion Warranty for New Homes

Tarion administers the Ontario New Home Warranties Plan Act warranty for new homes built by registered builders. Structural warranty coverage under Tarion:

Major structural defect coverage is the most significant structural protection within the Tarion framework. To trigger that coverage, the defect generally must involve a load-bearing element and materially threaten structural integrity. A P.Eng structural assessment is often key evidence in establishing a serious Tarion structural claim.

ODACC Adjudication

The Ontario Dispute Adjudication for Construction Contracts (ODACC) authority was established under the Construction Act 2018 to provide a fast, binding, interim dispute resolution process for Ontario construction contracts. Key features:

• Scope: Adjudication applies to disputes about payment under an invoice or certificate, amounts retained as holdback, payment or non-payment under a proposed payment certificate, set-offs, and notices of non-payment
• Not within ODACC scope: Complex defect liability claims involving design negligence, structural failure causation analysis, or substantial performance disputes that require extensive expert evidence generally exceed ODACC scope and proceed through the courts
• Process: Either party can trigger adjudication by serving a Notice of Adjudication. The parties then either agree on an adjudicator or ODACC appoints one, and the adjudicator issues a decision on the current statutory timetable
• Binding interim decision: The adjudicator's decision is binding and immediately enforceable but is "interim" — parties can still pursue the same issues in litigation or arbitration after adjudication

Limitation Periods

Ontario construction defect claims are subject to the Limitations Act, 2002. In practice, that means claim timing depends both on discoverability and on an ultimate outside cut-off period. For latent defects, the key legal issue is often when the claimant knew or reasonably ought to have known that a claim existed.

Because limitation analysis is heavily fact-dependent, owners should not assume a defect is still actionable simply because it was discovered recently. Once a serious structural issue is suspected, legal advice and technical documentation should be obtained quickly.

Structural Engineer as Expert Witness

In Ontario construction defect litigation, the structural engineer provides expert evidence on:

• Whether the construction work conformed to the contract documents, the applicable codes (OBC, NBCC), and accepted engineering practice in Ontario
• Whether an identified defect constitutes a "major structural defect" under the Tarion warranty definition
• The cause and origin of structural failure or damage
• The scope and cost of structural remediation required
• Whether the design-of-record was adequate or whether the defect was attributable to a design error

Structural engineers serving as expert witnesses in Ontario must satisfy Rule 53.03 regarding independence, qualifications, and opinion disclosure — see below.

Rule 53.03 Obligations

Ontario Rules of Civil Procedure Rule 53.03 prescribes strict requirements for expert evidence in Ontario Superior Court proceedings. A structural engineer retained as a testifying expert must:

1. Provide a signed expert report meeting the requirements of Form 53A — including: the expert's qualifications; the instructions received; the nature of the opinion and the reasons for it; the literature relied upon; and a signed acknowledgement of the expert's duty to the court
2. Include the statement: "I acknowledge that it is my duty to provide evidence in relation to this proceeding that is fair, objective and non-partisan"
3. Disclose the expert's relationship to the retaining parties
4. Certify that the report contains all information the expert is willing to provide regarding the subject-matter of the evidence
5. Serve the report on the schedule required by the Rules of Civil Procedure and any court order in the proceeding

Non-compliant expert reports can be excluded from evidence — a significant tactical disadvantage in litigation. Structural engineers acting as testifying experts in Ontario must understand and satisfy these obligations before their engagement commences.