Case snapshot
At a glance
- Case
- Can a Subcontractor Back Out of a Construction Bid in Ontario?
- Court / Tribunal
- Ontario Superior Court of Justice
- Citation
- 2026 ONSC 4517 ↗
- Date
- August 5, 2026
- Area of law
- Litigation Law
- Key issue
- Whether a subcontractor is contractually bound to honour its bid and enter into a subcontract once a general contractor accepts that bid in a tendering context.
- Outcome
- The court found the subcontractor in breach of its tendering obligations and awarded the general contractor damages equal to the difference between the subcontractor's original bid and the amount paid to the replacement subcontractor.
- Why it matters
- Contractors and subcontractors across Ontario need to understand that a bid submitted during a tender process can be legally binding — walking away after acceptance can result in a damages award.
Legal principle
The rule from this case
Ontario courts have long recognized that construction tendering creates two distinct contracts. The first — often called Contract A — comes into existence when a subcontractor submits a bid in response to a call for tenders. That contract obligates the bidder to keep its bid open and, if selected, to enter into the actual construction subcontract (Contract B). Critically, the general contractor does not need to formally communicate its acceptance to the subcontractor for Contract B to come into existence — acceptance in a tendering environment can be implied by the act of relying on the bid. This case reaffirms that these principles apply not just to general contractors bidding to owners, but also to subcontractors bidding to general contractors. A subcontractor that refuses to sign a Letter of Intent or threatens legal action is not automatically excused from its obligations. Where a standard industry form (here, the CCA1) is incorporated by reference, the subcontractor must follow its dispute resolution and negotiation procedures before walking away — failure to do so can itself constitute a breach.
Important limits
What this does not mean
This decision does not mean every quote or estimate a subcontractor sends is automatically a binding bid. The tendering framework depends on the specific circumstances: there must be a formal tender process with clear terms, and the bid must be submitted in response to that process. Casual pricing conversations or preliminary estimates are unlikely to attract the same obligations. The case also does not stand for the proposition that a subcontractor has no legitimate grounds to object to a subcontract's terms. Reasonable objections — properly raised and pursued through the agreed dispute resolution process — remain available. What this decision makes clear is that simply refusing to sign or threatening litigation, without engaging in the required negotiation steps, will not shield a subcontractor from liability.
Can a Subcontractor Be Held to Its Bid After a General Contractor Accepts It?
Yes — in Ontario’s construction tendering environment, a subcontractor that submits a bid and is selected can be legally bound to honour that bid and enter into the subcontract. The Ontario Superior Court of Justice confirmed this principle in Manorcore Group Inc. v. IBL Structural Steel Limited, 2026 ONSC 4517 (CanLII), a decision that has direct consequences for anyone involved in construction procurement across the province.
If you are a general contractor whose subcontractor has walked away from a bid, or a subcontractor unsure of your obligations after submitting a tender, understanding how Ontario courts treat construction bids is essential.
What Is the Difference Between Contract A and Contract B in Construction Tendering?
Contract A is the binding agreement that comes into existence the moment a subcontractor submits a compliant bid — it obligates the bidder to keep the bid open and, if selected, to enter the actual construction subcontract. Contract B is the actual subcontract that follows acceptance of the bid.
This two-contract framework, established in the Supreme Court of Canada’s Ron Engineering decision and developed further in cases like Naylor Group, applies not only to general contractors bidding to project owners but also to subcontractors bidding to general contractors. The court in Manorcore applied these principles directly to the subcontractor relationship, confirming that a structural steel subcontractor was bound by the same rules as any other bidder in a formal tender process.
Does a General Contractor Need to Formally Notify a Subcontractor That Its Bid Was Accepted?
No — in a tendering environment, formal communication of acceptance is not always required for Contract B to come into existence. The court confirmed that a general contractor’s reliance on a subcontractor’s bid — for example, by incorporating it into the general contractor’s own bid to the owner — can be sufficient.
This is an important practical point. Subcontractors sometimes assume that until they receive a signed subcontract or a formal letter of award, they are free to withdraw. That assumption can be legally wrong. Once a bid is submitted into a formal tender process and relied upon, the subcontractor may already be bound.
Is Refusing to Sign a Letter of Intent a Reasonable Objection?
Not on its own — the court found that simply refusing to sign a Letter of Intent, or signalling an intention to pursue legal action, does not amount to a reasonable objection that excuses a subcontractor from its tendering obligations. A bare refusal is not enough.
The subcontract in this case incorporated the CCA1 standard form by reference, which includes dispute resolution and negotiation obligations. The court found that the subcontractor failed to engage in those required steps before walking away. Skipping the contractually required negotiation process and heading straight to refusal — or threats of litigation — was itself treated as a breach of the subcontractor’s obligations.
How Are Damages Calculated When a Subcontractor Backs Out of a Bid?
Damages are measured as the difference between what the general contractor paid the replacement subcontractor and the original bid price. The court in Manorcore applied this straightforward measure: the general contractor was entitled to recover the extra cost it incurred by having to go to the market for a replacement.
The court rejected arguments that any reimbursement from the project owner should reduce the damages award, finding that evidence of such reimbursement was speculative. Prejudgment interest was also awarded under the Courts of Justice Act. The quantum was calculated from the stipulated price contract and the bids on record — a reminder that well-documented tendering records matter enormously when a dispute ends up in court.
What Role Do Standard Form Contracts Like the CCA1 Play in Subcontractor Disputes?
Standard form contracts incorporated by reference carry full legal weight — if the CCA1 is referenced in a subcontract or Letter of Intent, its dispute resolution and negotiation obligations are binding on both parties. The court treated the subcontractor’s failure to follow CCA1 procedures as a meaningful factor in finding a breach.
This means that before a subcontractor takes any unilateral step — refusing to proceed, withdrawing a bid, or threatening litigation — it should carefully review what dispute resolution steps the applicable standard form requires. Skipping those steps can turn a legitimate grievance into a losing legal position.
Practical Takeaways for Contractors and Subcontractors
- Subcontractors: Once you submit a bid into a formal tender process, treat it as potentially binding. Do not assume you can walk away simply because you have not yet signed a formal subcontract.
- General contractors: Document your reliance on subcontractor bids carefully — your records of incorporating a subcontractor’s price into your own bid can be critical evidence if a dispute arises.
- Both parties: If a dispute arises after bid acceptance, review the standard form contract (such as the CCA1) for mandatory negotiation and dispute resolution steps before taking any unilateral action.
- Watch for LOI refusals: A subcontractor’s refusal to sign a Letter of Intent is not automatically a reasonable objection — courts will look at whether proper process was followed.
- Keep records: Damages in tendering disputes are calculated from documented bid prices and replacement costs. Organized records of all bids, revised quotations, and replacement contracts are essential.
Our Ontario litigation lawyers regularly advise contractors, subcontractors, and project owners on tendering disputes and construction contract enforcement across the province. Whether you are in Hamilton, Mississauga, or anywhere else in Ontario, early legal advice can make the difference between recovering your losses and absorbing them.
If you are facing a construction tendering dispute or a subcontractor has walked away from a bid, contact UL Lawyers for a free initial consultation at our Burlington office. We serve clients across Ontario and can help you understand your rights and options — reach out through our construction and civil litigation practice page to get started.
This article is automated commentary on a public court decision and is for general information only — not legal advice. Decisions rely on facts unique to each case. If you are affected by a similar issue, contact a lawyer for advice specific to your situation.
FAQ
Frequently asked questions
Not necessarily. Once a subcontractor submits a bid into a formal tender process and the general contractor relies on it, a binding Contract A may already exist. Withdrawing at that point can expose the subcontractor to a damages claim for any extra costs the general contractor incurs finding a replacement.
The general contractor can typically claim the difference between the original subcontractor's bid price and the amount it had to pay a replacement subcontractor to complete the same work. Courts in Ontario have applied this measure of loss in tendering disputes.
Yes, if the CCA1 is incorporated by reference into a subcontract or Letter of Intent, its terms — including dispute resolution and negotiation obligations — are legally binding on both the general contractor and the subcontractor.