Contractor Wins Construction Dispute: Expert Evidence Excluded

Residential construction disputes often turn on issues of contract performance, payment milestones, and expert evidence regarding alleged deficiencies.

A recent Ontario decision illustrates how courts approach these issues, particularly where a homeowner refuses payment after substantial completion of a construction project.

The decision discussed in this article is 1579959 Ontario Inc. v. Sheikh, 2025 ONSC 185, a residential construction dispute decided by the Ontario Superior Court of Justice. The case arose from a renovation contract involving the conversion of a sunroom into a year-round living space. The litigation ultimately addressed issues of substantial performance, repudiation of contract, and the admissibility of expert evidence in construction disputes.

In this case, the Ontario Superior Court of Justice found in favour of the contractor after a four-day trial, concluding that the project had been substantially completed and that the homeowners' refusal to make the next contractual payment amounted to repudiation of the contract. The decision was later upheld by the Divisional Court on appeal, confirming the contractor's entitlement to payment.

This case highlights several important principles in Ontario construction litigation, including:

• The legal test for substantial performance of a construction contract
• The consequences of an owner's repudiation of a contract
• The strict requirements for admissibility of expert evidence

Construction disputes in Ontario frequently arise from residential renovation projects where disagreements develop over payment milestones, alleged deficiencies, or claims that work has not been completed. Courts applying Ontario's Construction Act often focus on whether the contractor has substantially performed the contract and whether the owner's refusal to pay constitutes a repudiation of the agreement.

Key Legal Principles Confirmed

• Substantial performance of construction contracts
• Strict qualification requirements for expert evidence
• Appellate deference to trial findings

Background of the Construction Dispute

The dispute arose from a residential renovation project involving the conversion of an existing sunroom into a year-round living space, including structural modifications and upgraded glazing.

The parties' contractual relationship evolved through several quotations before ultimately resulting in a written contract governing the work.

Over the course of several months, the contractor carried out the renovation. During construction, the scope of work expanded after the homeowners selected an upgraded option that required additional structural changes and modifications to the project design.

The homeowners initially made partial payments. However, they later refused to pay an invoice issued at the stage the contractor claimed the project had reached 97% completion, a milestone tied to the contract's payment schedule.

The homeowners alleged that:

• The work was incomplete
• The contractor had abandoned the project
• Significant deficiencies remained

The contractor commenced an action seeking payment for work performed under Ontario's Construction Act.

Trial Decision — Court Finds Substantial Performance

Following a four-day trial, the Ontario Superior Court of Justice ruled in favour of the contractor.

The trial judge concluded that:

• The contractor had substantially performed the construction contract
• The project had reached approximately 97% completion
• The homeowners were not justified in refusing payment
• The homeowners' refusal to make the contractual payment amounted to repudiation of the agreement

The court awarded the contractor $105,804.92, together with interest and substantial costs.

The decision reinforces a key principle in construction law: an owner cannot withhold payment simply because minor work remains outstanding where the contract has been substantially performed.

Court Excludes Homeowner's Proposed Expert Witness

A significant issue at trial concerned the homeowners' attempt to rely on a proposed expert witness to support their allegations that the project was incomplete and contained construction deficiencies.

The trial judge conducted a voir dire to determine whether the proposed expert could be qualified.

After reviewing the witness's qualifications and hearing evidence regarding his experience, the court declined to admit the proposed expert evidence.

The judge found that the homeowners had not demonstrated that the proposed expert possessed the necessary qualifications to provide opinion evidence on the technical issues in dispute.

As a result, the homeowners were left without expert evidence supporting their allegations regarding deficiencies or incomplete work.

This aspect of the decision underscores an important litigation principle: expert evidence must meet strict admissibility requirements before it can be relied upon in court. In 1579959 Ontario Inc. v. Sheikh, the trial judge conducted a voir dire to assess whether the homeowners' proposed expert possessed the necessary qualifications to provide opinion evidence regarding the alleged construction deficiencies. After reviewing the witness's affidavit, curriculum vitae, and testimony, the court concluded that the proposed expert lacked the required expertise and declined to qualify him as an expert witness.

Appeal to the Divisional Court

The homeowners appealed the trial decision to the Ontario Divisional Court in Sheikh v. 1579959 Ontario Inc. The Divisional Court ultimately dismissed the appeal and upheld the trial judgment in favour of the contractor.

They argued that the trial judge erred in several respects, including:

• Refusing to qualify their proposed expert witness
• Interpreting the construction contract
• Concluding that the project had reached 97% completion
• Finding that the homeowners had repudiated the agreement

The Divisional Court dismissed the appeal in its entirety.

The appellate court confirmed that:

• The qualification of an expert witness is a discretionary decision for the trial judge
• The trial judge provided detailed and sufficient reasons for excluding the expert evidence
• The trial judge's factual findings were supported by the evidentiary record
• Appellate courts must show deference to trial findings of fact

The Divisional Court also declined to grant leave to appeal the costs decision and ordered the appellants to pay $20,000 in costs of the appeal.

Construction Litigation in Ontario

The Ontario courts frequently address disputes involving construction contracts, contractor payment claims, and alleged deficiencies in residential renovation projects.

Disputes arising from residential construction projects frequently involve:

• Payment disputes under construction contracts
• Allegations of incomplete or defective work
• Issues relating to substantial performance
• Expert evidence regarding construction deficiencies
• Claims under Ontario's Construction Act

For contractors and property owners alike, the outcome of these disputes often depends on careful evidence preparation, expert testimony, and strategic litigation planning.

Construction litigation in Ontario can involve complex legal issues including construction lien claims, contract interpretation disputes, expert evidence admissibility, and appeals from trial decisions. Both contractors and property owners benefit from experienced litigation counsel when navigating disputes involving construction contracts and payment claims.

Learn more about our Construction Litigation services.

Representation

Calvin Zhang of Starkman & Zhang Lawyers represented the Plaintiff / Respondent contractor throughout the trial and the appeal.

This decision reflects the firm's experience in construction litigation, trial advocacy, and appellate advocacy, particularly in disputes involving construction contracts, payment claims, and lien-related issues.

Contact Construction Dispute Lawyers in Ontario

Starkman & Zhang Lawyers regularly represents clients in complex construction disputes, including:

• Contractor payment claims
• Residential and commercial construction disputes
• Construction lien litigation
• Contract interpretation disputes
• Trial and appellate proceedings

Our firm acts for contractors, developers, and property owners in litigation before the Ontario Superior Court of Justice and the Divisional Court.

Learn more about our broader Commercial Litigation practice.