Construction Deficiency Claims in Ontario

A deficiency is work that falls short of what the contract required, the applicable building code demands, or — where neither is specific — a reasonable standard for similarly skilled work. In practice, that covers a wide range: uneven flooring, drywall seams that show through paint, a roof that leaks at a flashing detail, electrical work that fails inspection, or finishes that simply do not match the materials specified in the contract.

A deficiency is different from normal wear and tear, which is the expected, gradual effect of time and ordinary use on a properly built component. Paint that dulls after several years, caulking that eventually needs refreshing, or a deck that weathers with age are generally not deficiencies — they are the ordinary life cycle of a building component that was built correctly in the first place. The distinction matters because warranty and deficiency claims generally focus on problems that trace back to how the work was originally performed, not the passage of time itself.

It is also worth distinguishing a deficiency from a simple difference of taste. If a contract called for a specific tile, paint colour, or fixture and that is what was installed, a homeowner who later decides they dislike the look generally does not have a deficiency claim — the work matches what was promised, even if the result is not what they would now choose. A deficiency claim turns on whether the work matches the contract and applicable standards, not on whether the outcome is aesthetically pleasing to the person who commissioned it. Where the contract itself was vague about a finish or detail, that ambiguity can become a genuine point of dispute, which is one more reason a detailed scope of work pays off well before any deficiency question arises.

A deficiency claim is only as strong as its documentation. Dated photographs taken from multiple angles, close up and from a distance, are the easiest and most useful starting point. A written list that describes each issue specifically — not “bathroom looks off” but “tile grout cracking along the tub-to-wall joint, approximately 1.5 metres” — gives both sides something precise to respond to, rather than a vague impression that is easy to dismiss.

Keeping a clear timeline also matters: when each deficiency was first noticed, when it was reported to the contractor, and how the contractor responded. This timeline often becomes important later, both for showing the deficiency was raised promptly and for establishing whether it was raised within any applicable warranty period.

It is generally worth organizing this documentation into a single, dated deficiency list rather than scattering photos and notes across texts and emails. A consolidated list that a contractor can review item by item, acknowledge in writing, and work through methodically tends to move faster toward a resolution than a running series of informal complaints raised piecemeal as they are noticed.

Holdback — generally 10 percent of the contract price under the Construction Act, retained by the owner for a set period after substantial performance — gives an owner real, practical leverage to have deficiencies addressed before the full contract price is released. Because the contractor generally wants that holdback released as soon as possible, outstanding deficiencies are often resolved more quickly once a contractor understands that payment is genuinely tied to the work being completed properly.

It is worth distinguishing holdback from a direct withholding tied to the cost of a specific deficiency, which an owner can often also apply where the deficiency is genuine and the amount withheld reasonably corresponds to the likely correction cost. Withholding far more than a deficiency is actually worth can create its own dispute, so proportionality matters on both sides. Our guide to holdback requirements in Ontario covers the underlying mechanics in more depth.

Using holdback effectively generally means acting before it is released, not after. Once holdback has been paid out to a contractor, an owner loses a significant piece of practical leverage and is left relying mainly on a demand letter or court claim to get outstanding deficiencies addressed. This is one reason a thorough walkthrough and a written deficiency list before any holdback release are worth prioritizing, rather than treating them as something to get to later.

Most construction and renovation contracts include a warranty clause describing how long the contractor remains responsible for correcting deficiencies after the work is finished, and under what process a correction request should be made. Many residential contracts use a one- to two-year warranty on workmanship, which generally runs separately from, and in addition to, any manufacturer warranties on fixtures or appliances installed during the project.

New home buyers purchasing from a licensed vendor may also have separate statutory warranty protections through Tarion, which operate on their own distinct timelines and claims process, independent of whatever warranty language appears in the purchase agreement itself. It is generally worth doing a thorough walkthrough and submitting any deficiency list in writing before a warranty period ends, since deficiencies raised after expiry can be considerably harder to pursue.

Some contracts also distinguish between a general workmanship warranty and narrower warranties on specific systems — a roof, a foundation waterproofing membrane, or a major mechanical system — that may run for a different length of time than the general warranty. Reading the warranty section closely rather than assuming a single period applies to everything in the project is worth doing early, so expectations around coverage are clear well before any deficiency actually surfaces.

When a contractor refuses or fails to correct a genuine deficiency, a written demand letter is usually the sensible first step — describing the deficiencies specifically, referencing the relevant contract or warranty terms, attaching supporting photos or reports, and setting a reasonable deadline for a response. A clear, well-documented demand letter resolves many deficiency disputes without anything further being necessary.

If that does not resolve the matter, an owner’s options generally include hiring another contractor to complete the correction and claiming the reasonable cost of doing so, pursuing a claim in Small Claims Court for smaller amounts, or in the Superior Court of Justice for larger or more complex disputes. Where the dispute instead arises because a contractor registers a lien over amounts the owner is withholding for deficiencies, our guides to construction liens and discharging a construction lien explain how that process generally works from the other direction.

Document everything as it comes up, not after the fact, and keep correspondence with the contractor in writing wherever possible rather than relying on verbal conversations alone. Reviewing the original contract — including its scope of work, warranty clause, and any holdback or payment terms — is usually the best starting point before deciding how to proceed. Our tools and checklists include resources to help organize a deficiency review.

Where disputes touch on broader issues like unpaid holdback, prompt payment timelines, or a general contractor-subcontractor relationship, our overviews of homeowner-contractor disputes and construction adjudication in Ontario may also be useful. This article explains how deficiency claims generally work in Ontario; it is not legal advice about a specific project, and our contact page can help point toward further resources.