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Construction Change Orders in Ontario
Ontario construction contractsChange ordersScope, price + schedule control
Construction Change Orders in Ontario: Control Extras Before the Work Starts
A good change order does more than record an extra price. It proves what changed from the original contract, includes deleted-work credits, shows labour and material calculations, identifies the contractor fee, states the schedule effect and records who approved the work before the cost becomes irreversible.
16 partsControlled change-order clause
8 typesChanges that must be classified
12 recordsComplete approval file
1 rulePrice and schedule before work
“Proceed now and we will work out the price later” is not a normal change order.
When urgent work cannot be priced in advance, use a written directive or not-to-exceed authorization with defined rates, records, markup and a spending cap.
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Eight different types of construction change
Owner-requested changeThe owner asks for different or additional work after the original scope was agreed.
Design changeArchitectural, structural, mechanical or electrical documents are revised.
Required-code changeAuthority review or inspection identifies work needed for approval or compliance.
Unknown-condition changeA verified concealed or differing condition requires a revised method or quantity.
Substitution changeA specified product is replaced because of availability, performance, owner choice or builder proposal.
Credit changeWork or material is deleted, downgraded or supplied by someone else and the owner receives a clear credit.
Construction-directive workUrgent or disputed work proceeds under a documented direction while price is determined later.
Contractor correctionWork required because of contractor error, damage, rework or omitted included scope—not automatically an owner extra.
Classification matters. Owner-requested upgrades, genuine concealed conditions and contractor corrections should not all be priced under the same assumption.
The 16 parts of a controlled change-order clause
1
Authorized decision-makers
CriticalDefine: Name the owner and contractor representatives who may request, price, approve and reject changes.
Control: State that site workers, family members, consultants and trades cannot bind the owner unless expressly authorized.
2
Change-request form
ProcessDefine: Require a numbered written request describing the reason, location and requested decision.
Control: Separate a request for pricing from permission to proceed.
3
Original-scope test
CriticalDefine: Identify the contract drawing, specification, allowance, exclusion or quantity affected.
Control: Do not label omitted included work as an extra merely because it was missing from the contractor’s estimate.
4
Added and deleted work
MoneyDefine: Describe both the new work and everything removed from the original scope.
Control: Require a credit for labour, materials, equipment, tax and fee no longer required.
5
Product details
ProcessDefine: Record manufacturer, model, dimensions, colour, performance and warranty.
Control: Attach product data and identify whether the item is an upgrade, downgrade or equal substitution.
6
Price breakdown
MoneyDefine: Separate labour, materials, equipment, subcontractors, delivery, disposal and consultant costs.
Control: Do not accept a lump sum when the contract promises itemized or cost-plus backup.
7
Contractor fee
MoneyDefine: State the percentage or fixed fee and exactly which net costs form the base.
Control: Prevent duplicate markup on subcontractor overhead, tax, credits or costs already containing the fee.
8
Allowances and credits
MoneyDefine: Reconcile the original allowance or included amount before adding the revised selection.
Control: Show the net change, not merely the gross price of the new item.
9
HST and holdback
MoneyDefine: Show HST separately and identify how statutory holdback applies to supplied change work.
Control: Do not confuse a deposit for special-order material with lien holdback.
10
Schedule effect
CriticalDefine: State added or saved calendar days, sequence impact and revised completion date.
Control: A blank schedule line should not become an unlimited delay claim later.
11
Design and permit effect
ProcessDefine: Identify revised drawings, consultant review, permit revision, fees and inspections.
Control: No construction should proceed from an uncoordinated sketch when professional or authority approval is required.
12
Approval before work
CriticalDefine: Require written approval before non-emergency changed work starts.
Control: State the consequence if the contractor proceeds without required approval.
13
Emergency work
ProcessDefine: Permit only work reasonably necessary to protect people, property or the improvement.
Control: Require prompt notice, photographs, daily records and a spending limit where practical.
14
Directive or not-to-exceed work
MoneyDefine: Define scope, hourly and unit rates, markup, recordkeeping and a maximum authorization.
Control: Require daily cost reporting and stop before exceeding the cap without further approval.
15
Billing and closeout
ProcessDefine: Require the approved change number on invoices and the project change log.
Control: Verify completion, inspections, warranties and credits before closing the item.
16
Disputed changes
ProcessDefine: Require written reasons, preservation of records and payment of undisputed amounts where applicable.
Control: Preserve negotiation, adjudication, mediation or other contract remedies without waiving rights.
Twelve records every approved change should contain
1
Change-order number
A unique sequential number tied to the project and contract.
A unique sequential number tied to the project and contract.
2
Request source
Owner, contractor, consultant, authority, site condition or supplier.
Owner, contractor, consultant, authority, site condition or supplier.
3
Original scope reference
Drawing, specification, allowance, quotation or contract clause being changed.
Drawing, specification, allowance, quotation or contract clause being changed.
4
Revised scope
Exact added, deleted or substituted work and affected location.
Exact added, deleted or substituted work and affected location.
5
Drawings and selections
Marked-up plans, product data, colours, models and approval status.
Marked-up plans, product data, colours, models and approval status.
6
Price breakdown
Labour, material, equipment, subcontractors, credits, fee, HST and holdback.
Labour, material, equipment, subcontractors, credits, fee, HST and holdback.
7
Quantity record
Measured units, hours, tickets, invoices and agreed unit rates.
Measured units, hours, tickets, invoices and agreed unit rates.
8
Schedule effect
Added days, changed sequence, procurement impact and revised completion date.
Added days, changed sequence, procurement impact and revised completion date.
9
Permit and consultant effect
Required design revision, engineering, municipal review or inspection.
Required design revision, engineering, municipal review or inspection.
10
Approval record
Name, signature or authorized electronic acceptance and date.
Name, signature or authorized electronic acceptance and date.
11
Invoice reference
Contract line, change-order number and billing status.
Contract line, change-order number and billing status.
12
Closeout status
Completed, inspected, credited, deficient, disputed or cancelled.
Completed, inspected, credited, deficient, disputed or cancelled.
How to calculate the net change
Upgrade with original creditNew flooring costs CAD $18,000. Original included flooring value is CAD $11,000.
CAD $18,000 − CAD $11,000 = CAD $7,000 net cost before authorized fee and taxCost-plus changeEligible labour, material and subcontractor cost totals CAD $20,000 with an agreed 15% fee.
CAD $20,000 + CAD $3,000 fee = CAD $23,000 before HST and holdbackUnit-price changeVerified 40 additional metres at an agreed CAD $175 per metre.
40 × CAD $175 = CAD $7,000 before stated fee and tax treatmentNot-to-exceed directiveApproved rates are used, but work must stop before total cost exceeds the written cap.
Actual verified cost ≤ authorized maximumIllustrations only. There is no universal Ontario change-order markup. The contract must define the fee, cost base, credits, HST and holdback treatment.
The change-order approval sequence
| Step | Required decision | Document | Do not proceed when |
|---|---|---|---|
| 1. Identify | What differs from the original contract and why? | Change request with scope reference. | The contractor cannot identify what original work is being changed. |
| 2. Investigate | Are design, permit, site or supplier facts confirmed? | Consultant response, site record or product information. | The proposed work is based on an assumption that can be checked first. |
| 3. Price | What are gross additions, deleted-work credits, fee, tax and net total? | Itemized quotation and backup. | The owner receives only one unexplained number. |
| 4. Schedule | Does the change add time, alter sequence or affect procurement? | Written added days and revised completion date. | The schedule field is blank or says “to be determined.” |
| 5. Approve | Does an authorized person accept scope, price and time? | Signed or clearly authenticated electronic change order. | The response is merely “please price” or “look into it.” |
| 6. Perform | Is the work built to the revised approved documents? | Site records and inspections. | Required consultant or permit approval is missing. |
| 7. Bill | Does the invoice match the approved change and completed value? | Invoice showing change-order number. | The billed scope or amount differs without a revised approval. |
| 8. Close | Are the work, credit, warranties and schedule adjustment complete? | Updated change log and closeout status. | Deleted work remains uncredited or deficiencies remain undocumented. |
Ontario consumer and prompt-payment rules
- Written renovation changes: Ontario’s homeowner guidance says a contractor generally cannot charge more than 10% above an estimate included in the contract unless the owner agrees to new work or a new price and signs a change to the contract.
- Consumer estimate rule: The current Consumer Protection Act, 2002 generally limits charges to 10% above an estimate incorporated into a qualifying consumer agreement, while allowing the parties to agree to additional or different work and an amended price.
- Contract wording still matters: The 10% estimate rule is not a universal cap on every fixed-price, cost-plus, allowance or commercial construction contract.
- Proper invoice identification: Where the Construction Act applies, a proper invoice identifies the contract or other authorization under which the changed work was supplied and describes the services or materials, including quantity where appropriate.
- Seven-day invoice deficiency notice: Since January 1, 2026, an invoice missing proper-invoice information can be deemed proper unless the owner gives written notice of the deficiency and required correction within seven days.
- Fourteen-day payment dispute: An owner disputing all or part of a proper invoice generally must deliver the prescribed non-payment notice within 14 days, stating the unpaid amount and every reason.
A change-order dispute and an invoice-form deficiency are not the same problem.
One may concern whether the work was authorized or included; the other concerns whether the payment request meets statutory invoice requirements. Both deadlines may need attention.
Official references: Ontario renovation rights, Consumer Protection Act, 2002, and Ontario Construction Act.
Bad wording versus controlled wording
Bad: price after completion
“The Contractor may make changes as required and charge the Owner the cost of the work plus the Contractor’s standard markup. Verbal owner instructions are binding.”
Better: scope, price, credit and time first
“Except for documented emergency protective work or a written directive issued under this Contract, no changed work shall proceed until an authorized representative approves a numbered written change order describing the original scope reference, added and deleted work, product details, labour, material, equipment and subcontractor costs, credits, Contractor Fee, HST, holdback treatment and schedule effect. A request to price, review or investigate is not authorization to proceed. If the price cannot reasonably be determined in advance, the Owner may issue a written not-to-exceed authorization stating scope, rates, record requirements, fee and maximum expenditure. Contractor error, rework, damage and omitted included scope are not owner changes merely because they create additional contractor cost.”
Educational example only. An Ontario lawyer should adapt authority, emergency work, directives, electronic approval, prompt payment and dispute wording to the actual project.
A change order signed after the invoice is an admission request—not proper budget control.
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Eight change-order red flags
!
Work starts before price or method is agreed
The owner loses the chance to compare options, decline the work or control the budget.
The owner loses the chance to compare options, decline the work or control the budget.
!
One-line change order
“Extra electrical — CAD $8,500” provides no quantity, labour, material, credit or markup detail.
“Extra electrical — CAD $8,500” provides no quantity, labour, material, credit or markup detail.
!
No credit for deleted work
The owner pays for both the original item and the replacement.
The owner pays for both the original item and the replacement.
!
Markup called standard
The percentage, cost base, subcontractor markup and HST treatment are not in the contract.
The percentage, cost base, subcontractor markup and HST treatment are not in the contract.
!
Schedule effect left blank
The contractor later claims delay even though the change was approved without one.
The contractor later claims delay even though the change was approved without one.
!
Contractor error billed as an owner change
Omitted included work, damaged material or rework is transferred to the owner.
Omitted included work, damaged material or rework is transferred to the owner.
!
Verbal approval treated as unlimited authority
A hallway conversation becomes permission for a much larger scope and price.
A hallway conversation becomes permission for a much larger scope and price.
!
Change order signed after invoicing
The owner is asked to approve a completed charge rather than authorize work prospectively.
The owner is asked to approve a completed charge rather than authorize work prospectively.
Twenty-four questions before approving a change
1
Who requested the change?
2
What contract item is changing?
3
Why is the change required?
4
Is it actually outside original scope?
5
What work is added?
6
What work is deleted?
7
What credit applies?
8
What products and quantities apply?
9
What labour hours and rates apply?
10
What equipment and unit rates apply?
11
What subcontractor quote supports it?
12
What contractor fee applies?
13
Is HST shown separately?
14
Is statutory holdback addressed?
15
Is a permit revision required?
16
Is consultant approval required?
17
What procurement delay results?
18
How many contract days are added?
19
What is the revised completion date?
20
Can a lower-cost alternative work?
21
Who has authority to approve?
22
Has written approval been given?
23
How will it appear on the invoice?
24
When will completion be verified?
Contract Centre and related guides
Construction change-order FAQ
Does every construction change in Ontario need a signed change order?
A written, signed change order is the safest process, but the complete facts matter. Emergency protective work, contractual directives, electronic approvals, conduct and other evidence can affect entitlement. Do not assume verbal work is automatically free or automatically payable.
Can a contractor charge more than an Ontario renovation estimate?
If an estimate forms part of a qualifying consumer agreement, Ontario guidance says the supplier generally cannot exceed it by more than 10% unless the consumer agrees to new work or a new price and signs a change to the contract.
What should a change order include?
At minimum: the original scope reference, exact added and deleted work, materials, quantities, labour, subcontractor costs, credits, contractor fee, HST, holdback treatment, schedule effect, approval and invoice reference.
Can the builder mark up a change order?
Yes if the contract authorizes the markup or fee. There is no universal Ontario percentage. The owner should confirm the fee base and whether subcontractor pricing already includes markup.
Who pays for contractor mistakes?
A contractor’s estimating error, damaged work, failed coordination or omission of included scope is not automatically an owner change. Contract wording, drawings, responsibility and facts determine entitlement.
What happens when the price cannot be known before work starts?
Use a written directive or not-to-exceed authorization that defines scope, labour and equipment rates, record requirements, fee, spending cap and daily reporting. Convert it to a final change order promptly.
Can an email approve a change order?
Potentially, depending on the contract, authority, wording and electronic-signature rules. The safest email clearly identifies the change, price, schedule effect and acceptance rather than saying only “go ahead.”
Can I refuse to pay an unsupported change on a proper invoice?
You may have contractual and statutory rights, but Ontario’s prompt-payment rules can impose short notice deadlines. Since January 1, 2026, invoice deficiencies generally must be identified within seven days, and disputed payment generally requires the prescribed notice within 14 days where the regime applies.
A change is not controlled until scope, money, time and authority are on the same page
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Reviewed July 30, 2026. General educational information only. This page is not legal advice and does not determine whether a specific change is authorized, included or payable.
