Suing a Contractor in Ontario for Defective Work

Few situations are more frustrating than paying a contractor for work that turns out to be shoddy, incomplete, or downright dangerous. Whether it is a botched bathroom renovation, a roof that leaks after the first rain, or foundation work that was never done properly, defective construction work is a real and recurring problem — and Ontario law gives homeowners and property owners meaningful remedies.

Pursuing a contractor for defective work requires preparation, documentation, and a clear understanding of your legal options. This guide walks you through the process.

Step 1 — Document Everything Before You Do Anything Else

Before you send a letter, post a review, or withhold payment, your first priority is to document the defects thoroughly. Once a dispute begins, the contractor may dispute the cause or extent of the problem, and your ability to prove what happened depends entirely on the evidence you preserved.

Effective documentation includes:

• Photographs and video — date-stamped if possible; capture the full scope of the problem from multiple angles.
• Written records — note when you first observed each defect, what conditions existed, and any conversations you had with the contractor about it.
• The original contract — including any specifications, drawings, and change orders. If the contract was oral, write down everything you remember about what was agreed, with dates.
• Payment records — invoices, cheques, e-transfer confirmations, receipts. You need to show you paid (or are liable to pay) for the work.
• Communications — every text, email, voicemail, and letter between you and the contractor. Do not delete anything.

If the defective work poses a safety risk (an electrical fault, structural instability, water infiltration), get it assessed by a qualified professional before it worsens further. Keep every invoice and report from any expert you consult.

Step 2 — Understand Your Legal Basis

Your claim against a contractor may rest on several grounds, often in combination:

Breach of Contract

If you had a written or oral contract specifying the scope and quality of the work, a contractor who delivers substandard work has breached that contract. The standard of performance is usually what was specified, and where the contract is silent, courts imply a standard of workmanship that is reasonable in the circumstances — typically understood as work done in a good and workmanlike manner.

Implied Warranties

Even where a contract does not spell out quality standards in detail, Ontario common law implies certain warranties into contracts for services: that the work will be done with reasonable care and skill, and that materials supplied will be fit for their intended purpose. A contractor cannot escape liability simply because the contract said nothing about quality.

Negligence

In some circumstances, particularly where there is personal injury or property damage, a claim may also lie in negligence. Negligence requires showing that the contractor owed a duty of care, breached the standard of care expected of a reasonably competent contractor in that trade, and that the breach caused your loss.

Statutory Consumer Protections

If your contract was a consumer contract for goods and services, Ontario's consumer protection legislation may provide additional rights. Certain home renovation contracts have specific requirements about written contracts, cancellation rights, and deposit limits. If those requirements were not met, the contractor may have additional exposure.

Step 3 — Send a Demand Letter

Before filing a claim, send a formal demand letter — ideally prepared or reviewed by a lawyer — setting out the defects, the contract terms that were not met, the cost to repair or complete the work, and a clear deadline for the contractor to respond or remedy the situation.

A demand letter accomplishes several things:

• It puts the contractor on formal notice, which they cannot later claim they did not have.
• It gives them an opportunity to remedy the defect without litigation — which some will take, especially if they want to preserve their reputation.
• It establishes a paper trail showing you acted reasonably before going to court.
• It often leads to settlement, saving both parties the time and cost of litigation.

Retain copies of everything you send and receive.

Step 4 — Choose the Right Court

The venue for your claim depends primarily on the dollar amount of your losses.

Small Claims Court handles claims up to the current monetary limit (as of writing, $35,000 — verify the current limit, as it is set by regulation and may change). Small Claims Court is designed to be accessible to self-represented parties, the procedures are simpler, and costs awards are modest. It is well-suited to relatively straightforward defective work claims within the monetary limit.

Superior Court of Justice is required for claims exceeding the Small Claims limit, or where the nature of the relief sought (injunction, specific performance) falls outside Small Claims Court's jurisdiction. Superior Court involves fuller procedural steps — pleadings, documentary discovery, oral examinations — and legal representation becomes much more important.

If your losses sit just above the Small Claims limit, you have the option to abandon the excess to keep the case in Small Claims — but this is a strategic decision to make with legal advice, not by default.

Step 5 — Expert Evidence

Defective work claims almost always require expert evidence — the opinion of a qualified professional who can explain, in terms a judge can understand, what the contractor did wrong and what it will cost to fix.

For construction defects, this typically means:

• A building inspector, engineer, or trades professional who can inspect the defective work, identify the specific failures, explain the applicable standard of workmanship, and quantify the remediation cost.
• Remediation quotes from other contractors — at least two or three, to establish a fair market cost for repair.

The expert's written report (and their attendance at trial if the case goes that far) is often the single most important piece of evidence in a defective work case. A judge who is not a tradesperson needs expert help to understand why the work was defective and what it cost to fix.

In Small Claims Court, expert evidence can be submitted in writing, with the expert available to attend if necessary. In Superior Court, the procedural requirements for expert evidence are more formal.

Step 6 — What Damages Can You Recover?

If you succeed, the court can award:

• Cost of remediation — the reasonable cost to repair the defective work or complete unfinished work.
• Cost of consequential damage — for example, water damage to interior finishes caused by the leaking roof the contractor installed.
• Any additional costs beyond the original contract price you reasonably incurred as a result of the breach (hiring another contractor, emergency repairs, temporary accommodation if the property was uninhabitable).
• Pre-judgment interest — interest on your damages from a date set by the court.
• Partial costs — in Superior Court, the winning party is typically awarded a contribution toward their legal fees; in Small Claims, costs awards are more limited.

You are expected to mitigate your damages — meaning you must take reasonable steps to limit the harm. If you knew about a defect and delayed repairs, allowing it to worsen, a court may reduce your damages by the amount the delay made worse.

Frequently asked questions