Construction Contract Ontario: What to Check Before You Sign

The contract is where the build goes right or wrong

A construction contract is not paperwork you rush through to get to the fun part. It is the single document that defines what you are buying, what it costs, when you pay, what happens when something changes, and who carries the risk when things go sideways. The homeowners who get burned almost always have the same regret in common: the contract was vague, and the vagueness only worked in one direction.

The good news is that the failure points are predictable. Fix these five and you have removed the vast majority of the disputes that wreck builds and friendships.

Pain point #1: Vague scope and fantasy allowances

This is the number-one source of disputes, full stop. Two people can read “finish the basement” or “supply and install kitchen” and picture two completely different projects at two completely different prices. When the scope is loose, every gap becomes a negotiation later – and you are negotiating from the weak position of a half-built house.

Allowances are where this gets expensive. An allowance is a placeholder dollar figure for items you have not chosen yet – flooring, cabinets, fixtures, tile, lighting, windows. The classic trap: a builder quotes low allowances to make the headline price look great, you fall in love with finishes that cost three times the allowance, and the difference comes back as change orders. The build was never really cheaper; the surprise was just deferred.

• Demand a detailed scope – room by room, system by system, with brand or grade-level examples, not one-line descriptions.
• Pressure-test the allowances – ask “if I want the finishes in these photos, are these allowances realistic?” If the answer is fuzzy, the budget is fiction.
• Get a written exclusions list – the things not in the price (landscaping, window coverings, appliances, site servicing) cause as many fights as what is included.

For the full anatomy of a proper agreement, see what a good construction contract should include.

Pain point #2: Paying too much, too soon

The homeowners with the worst outcomes almost always have one thing in common: they paid well ahead of the work that was actually done. The further your money runs in front of completed work, the more exposed you are if the builder stalls, underperforms, or goes under.

Your payment schedule should track real milestones, not calendar dates. Money should be released after a stage is genuinely complete – not because it is the first of the month. Most healthy schedules land in the three-to-five draw range, with each draw tied to a verifiable point in the build.

Pain point #3: Change orders that live in text messages

Builds change – that is normal. The damage comes from changes that are agreed verbally, built immediately, and priced “later.” Later is where the disagreements live: you remember one number, the builder remembers another, and the work is already done. The fix is a single, non-negotiable rule.

Your contract should spell out the change-order process: how a change is requested, how it is priced, how long the builder has to respond, and that no change proceeds without written sign-off from both sides.

Pain point #4: A timeline with no teeth

“We should be done by summer” is not a schedule. A useful contract names a start date and a target for substantial completion, defines what substantial completion actually means, and says what happens if the builder is badly late for reasons within their control. It should also be fair to the builder – genuine delays from weather, permit timelines, or owner-caused changes are legitimate and should be accounted for.

You will not get a guaranteed date on a custom build, and you should be suspicious of anyone who promises one. What you should get is a realistic schedule, a clear definition of “done,” and a process for handling delay – so “a few more weeks” cannot quietly become a year.

Pain point #5: What happens if the builder disappears

It is the nightmare scenario, and it happens: a builder stalls, runs out of money, or folds mid-project. Your exposure in that moment is almost entirely determined by the contract you signed and how far ahead you paid. If you kept payments tied to completed work and the holdback intact, the damage is survivable. If you prepaid heavily, it can be devastating.

Protect yourself before you ever need to: confirm the builder’s insurance and WSIB coverage, keep payments behind the work, and understand your lien and holdback rights. We cover the recovery playbook in detail in what to do if your builder goes out of business mid-project.

Ontario protections worth knowing before you sign

• Builder licensing (HCRA): in Ontario, builders and vendors of new homes must be licensed by the Home Construction Regulatory Authority. Confirm your builder is licensed and in good standing.
• Tarion warranty: most newly built homes from a registered builder carry the Tarion new-home warranty (deposit protection plus coverage that steps down over the first years). Confirm whether your build is covered and what the warranty includes.
• Construction Act: Ontario’s lien and prompt-payment rules, including the statutory holdback, exist to protect owners and subtrades – make sure your contract and lawyer handle them properly.
• A lawyer’s review is cheap insurance: for a custom build or major renovation, a short legal review of the contract before signing is inexpensive next to the cost of a dispute. If a clause is confusing, that is exactly the clause to ask about.

Rules, thresholds, and warranty terms change and vary by situation – confirm current requirements with the relevant authority and a construction lawyer before you rely on them.

The clauses a good contract must spell out

Use this as a pre-signing checklist. If your contract is silent on any of these, ask for it in writing:

• Scope of work – detailed, room by room, with inclusions and a clear exclusions list.
• Price and price type – fixed price vs. cost-plus, and exactly what each means for you.
• Allowances – realistic dollar figures, and how over/under-allowance amounts are reconciled.
• Payment schedule – deposit, milestone-based draws, holdback, and late-payment terms.
• Change-order process – written, priced, and signed before work proceeds.
• Schedule – start, substantial completion, definition of “done,” and delay handling.
• Warranties – workmanship warranty plus Tarion (where applicable).
• Insurance and WSIB – the builder’s coverage, named and verifiable.
• Permits and responsibility – who pulls permits and who is responsible for code compliance. See our building permit guide.
• Dispute resolution – how disagreements get handled before they reach a courtroom.
• Cleanup and completion – site cleanup, deficiencies, and final-payment conditions.

Red flags to catch before you sign

Frequently asked questions

How big should a deposit be on a construction contract in Ontario?

There is no single legal number, but the principle is simple: a modest deposit to secure your spot is normal, and your payments should stay behind the completed work after that. Be wary of large upfront sums, and prefer deposits held in a lawyer’s trust account where possible. New-home builds from a registered builder also carry Tarion deposit protection up to set limits.

Fixed price or cost-plus – which is safer?

Fixed price gives you budget certainty but the builder prices in risk; cost-plus can be transparent but exposes you to overruns if scope and allowances are loose. Neither is “safer” on its own – what protects you is a detailed scope, realistic allowances, and a clear change-order process, regardless of price type.

Do I really need a lawyer to review my contract?

For a custom home or major renovation, yes – it is inexpensive relative to the cost of a dispute. A construction lawyer will flag deposit and payment risks, unclear scope, weak change-order terms, and holdback or lien issues before you sign, when you still have leverage.

What is the holdback and why does it matter?

Ontario’s Construction Act requires a statutory holdback (commonly 10% of the contract) to protect against liens from unpaid subtrades and suppliers. Handled correctly, it is a key protection for you as the owner – make sure your contract and lawyer address it.

Disclaimer: This article is educational and general in nature, not legal advice. Construction law, warranty programs, and licensing rules in Ontario change and depend on your specific situation. Always confirm current requirements with the relevant authority and have a qualified construction lawyer review your contract before you sign.