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    How Construction Bidding Works in Ontario: A Complete Guide

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    The short answer

    Ontario construction bidding is a structured process where owners post a tender, qualified bidders price the work using supplied drawings and specs, and the lowest compliant bid usually wins. The process is governed by the Construction Act and common-law tender rules (Contract A and Contract B). Knowing the rules, the timelines, and the documentation requirements is the difference between winning and being disqualified.

    Key takeaways

    • Owners post a tender, bidders price the supplied drawings and specs, and the lowest compliant bid usually wins.
    • Bidding is governed by the Construction Act and common-law tender rules (Contract A and Contract B).
    • Knowing the rules, timelines, and documentation requirements decides who gets disqualified.
    21+ days
    Typical public tender open period
    10%
    Standard bid bond amount
    Contract A
    Created on bid submission
    Construction Act
    Governs Ontario payment

    What types of construction tenders exist in Ontario?

    Ontario uses several tender formats depending on who the owner is and what they are buying:
    • Open public tender: anyone qualified can bid. Most common for public sector work.
    • Invitational tender: only pre-qualified or invited bidders. Common in private work.
    • Request for Proposal (RFP): evaluated on price plus qualifications, methodology, experience.
    • Request for Qualifications (RFQ): first stage to shortlist bidders before a tender.
    • Design-Build: a single bid covers both design and construction.
    • CCDC standard contracts (2, 5A, 5B, 14) are used for most Ontario projects.

    What are Contract A and Contract B?

    This is the legal foundation of Ontario tendering, set by the Supreme Court of Canada in Ron Engineering. When you submit a compliant bid, you automatically form Contract A with the owner. Contract A binds the owner to evaluate your bid fairly and binds you to your bid price for the time stated in the documents. Contract B is the actual construction contract, formed when the owner accepts a bid. The practical takeaway: a compliant submitted bid is legally binding. You cannot casually withdraw without losing your bid bond.

    What documents come with a tender?

    A standard Ontario tender package includes: instructions to bidders, the bid form, drawings, specifications, supplementary conditions, the proposed contract (usually a CCDC document), and any geotechnical or environmental reports. Addenda are issued during the bid period to clarify questions or change scope. Every bidder must acknowledge every addendum on the bid form or risk being declared non-compliant.

    When do I need bid, performance, and payment bonds?

    Public Ontario projects above roughly $500,000 typically require a 10% bid bond at submission. On award, the contractor provides a 50% performance bond and a 50% labor & material payment bond. Bonds are issued by a licensed surety based on your financial strength and track record. Subcontractors generally do not provide bonds to the owner but may be asked for them by the GC on larger work.

    What happens at bid closing?

    At the exact closing time, the tender closes. Most Ontario public bids are now electronic via portals like Bids&Tenders or MERX, which timestamp submission to the second. Late bids are rejected automatically. After closing, bids are usually opened and pricing is read aloud (or published online). The owner then reviews compliance, checks references and qualifications, and awards to the lowest compliant bidder, typically within 30 to 60 days.

    How does the Ontario Construction Act affect bidding?

    The Construction Act (formerly the Construction Lien Act) governs payment timing and dispute resolution on Ontario projects. Key items every bidder should know: prompt payment requires owners to pay within 28 days of a proper invoice, contractors must then pay subs within 7 days, and adjudication is the mandatory fast-track dispute process. Build these timelines into your cash flow assumptions when pricing a bid.

    How do subcontractors actually win more bids?

    Three things separate subs that win consistently from subs that grind: 1. Bid the right work. Saying no to mismatched projects raises your hit rate. 2. Get on bid lists earlier. Knowing about a project at design stage means you can call the GC before invitations go out, instead of being one of 12 quotes on bid day. 3. Quote faster and more completely. GCs reward subs who respond same-day with a clear scope letter, exclusions, and unit pricing. DataBid helps with the first two by surfacing Ontario projects at pre-design and showing which GCs are bidding.

    How to do it, step by step

    1. 1

      Find the tender

      Locate it on MERX, Biddingo, a municipal portal, or via a paid intel platform.

    2. 2

      Download the bid documents

      Drawings, specifications, instructions to bidders, and bid form.

    3. 3

      Review addenda

      Addenda are binding clarifications. Missing one can disqualify your bid.

    4. 4

      Take off and price the work

      Quantify materials and labor, get supplier and sub quotes, add markup.

    5. 5

      Secure bonding if required

      Bid bond at submission, performance and labor & material payment bonds at award.

    6. 6

      Submit before the closing deadline

      Late bids are rejected without exception. Submit early.

    Frequently asked questions

    How long does the Ontario construction bidding process take?

    Public tenders are typically open for 21 to 35 days from posting to closing. Award decisions usually come within 30 to 60 days after closing. From tender posting to project start can be three to six months on a typical mid-size Ontario project.

    Can I withdraw a bid after I submit it in Ontario?

    Generally no. Once you submit a compliant bid, Contract A is formed and your bid is irrevocable for the period stated in the instructions to bidders (usually 60 to 90 days). Withdrawing typically forfeits your bid bond and can disqualify you from future work with that owner.

    What disqualifies a bid in Ontario?

    Common disqualifications: late submission, missing bid bond, unsigned bid form, failing to acknowledge an addendum, qualifying or conditional bids, and arithmetic errors on the bid form that materially affect price. Public owners apply these rules strictly because of Contract A obligations to other bidders.

    Do I need a Master Business Licence to bid in Ontario?

    You need to be a legally registered business in Ontario or extra-provincially. Many public tenders also require WSIB clearance, COR safety certification, and proof of insurance at minimum limits stated in the tender documents.

    How is the lowest bidder actually chosen?

    On a straight tender, the lowest compliant bid wins. On an RFP, price is one factor among several (often weighted 30 to 50 percent), with the balance based on team experience, methodology, schedule, and references. Always read the evaluation criteria before pricing.

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