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How to Bid on Construction Jobs in Ontario (2026)

What this guide covers

If you are a small contractor trying to figure out how to bid on construction jobs in Ontario, you are in one of two camps: residential quoting (kitchens, bathrooms, additions) or formal tendering (commercial, public, larger private). The skills overlap. The paperwork does not. This guide walks both, and points out the spots where most contractors lose money before the work even starts.

What "bidding" actually means

In trades, the word covers two different things:

  1. Quoting a homeowner for a residential job. Informal. You walk through, take notes, send a quote within a few days.
  2. Submitting a tender for a posted construction project. Formal. There is a tender package, a deadline, evaluation criteria, and often a bid bond.

Most small Ontario contractors do both. Skip ahead to the tender section if residential is already in your rear-view mirror.

Step 1: Find jobs worth bidding on

Most small Ontario contractors find work three ways:

  • Word of mouth and referrals: still the highest-converting channel. Roughly 60% of small residential work comes from past clients and personal network.
  • Online lead platforms: HomeStars, Houzz, Google Local Services Ads. Pay-per-lead, conversion 5% to 15%.
  • Posted tenders: for projects above roughly $50,000 or commercial work, posted on bid platforms.

The main bid platforms used in Ontario:

  • Merx: thousands of public and private bids across Canada
  • Biddingo: paperless platform, search by postal code, public and private
  • BuildWorks Canada: 7,500+ active opportunities, mostly commercial
  • BidClerk: 400,000+ jobs across North America with custom alerts
  • Ontario Construction News: free posted tenders for Ontario specifically

Public tenders in Ontario are governed by Canadian tender law. The owner has a duty to evaluate fairly, accept only compliant bids, and use only disclosed criteria. You also have an obligation: stand behind your bid or pay the consequences for retracting it. A bid is a contract offer the moment you submit.

Step 2: Decide if the job is worth bidding

Most contractors bid too much. Bidding is unpaid sales work. A 30-page tender response can take 8 to 20 hours. If your win rate is 1 in 10, every win cost you 80 to 200 hours of free labour.

Filter every opportunity before you spend a minute pricing it:

  • Is the budget realistic? Most tenders list a price range. If your real cost is above the top of the range, walk away.
  • Are you a fit? If they want 10 years of multi-family experience and you have done five single-family builds, you will not win.
  • Can you deliver in their timeline? Late-stage tenders often have aggressive starts. If you are booked for 6 weeks, do not bid.
  • Do you have the bonding capacity? Public projects over $500,000 in Ontario require bid bonds (more on this below). If your surety capacity is $300K, public tenders above that are out.

Saying no to bad bids protects your time. A focused contractor wins one in four by being selective. A generalist wins one in fifteen by spraying everything.

Step 3: Estimate the job

This is where most bids die. Pricing too high loses the work. Pricing too low wins it and ruins you.

For a residential quote, the fast process:

  1. Walk through the site with the client, take photos and dimensions
  2. List every line of work: demolition, materials, labour hours, subs, permits, disposal
  3. Pull supplier prices the same week, not from memory
  4. Total your costs
  5. Apply your markup

For a tender, the package will include a Bill of Quantities or detailed scope document. Read it twice before pricing anything. Hidden specifications (a finish grade, a drawing revision, a particular product brand) are where contractors lose money.

Ontario-specific costs that get forgotten:

  • Permits: building permit fees vary by municipality. Toronto charges roughly $20 per $1,000 of construction value as a starting point. Most renovations also need an Electrical Safety Authority (ESA) permit and possibly a TSSA permit for gas work.
  • Disposal: bin rental in the GTA runs $250 to $500 per bin in 2026
  • WSIB clearance: required to be on file before starting on most commercial projects
  • HST: must be added if you are registered (mandatory if you earn over $30,000 in four consecutive quarters). State "plus HST" on every line.

Use a markup that protects overhead and profit. The "20% rule" most contractors quote is too low for an Ontario shop with realistic overhead. For real markup numbers by trade, see the Contractor Markup and Profit Guide Ontario.

Step 4: Write the proposal

A bid that wins has three parts: scope, price, and credibility.

Scope

  • List exactly what is included, line by line
  • List exactly what is excluded (this protects you on change orders)
  • Note your assumptions: "price assumes existing electrical panel is sufficient"
  • Reference drawings or specifications by date and revision number

Price

  • One total. Break it down only if asked.
  • "Plus HST" on every quote
  • Payment terms. Standard for small residential is 25% deposit, 25% at midpoint, 50% on completion. For larger jobs, monthly progress draws minus a 10% statutory holdback under the Ontario Construction Act.
  • Validity period. Most quotes hold for 30 days. State it on the document.

Credibility (for tenders, not for residential)

  • Company background, one page maximum, not ten
  • Two or three relevant project examples with photos and reference contacts
  • Insurance certificate (general liability, $2 million is the standard floor)
  • WSIB clearance certificate
  • Trade licences: ECRA/ESA for electrical, TSSA for gas, MLBO licence for HVAC, your general contractor licence if your municipality requires one
  • Bid bond if the tender requires it

For residential quotes, credentials belong in the in-person walk-through, not in the quote document. Send the price, the timeline, and the deposit terms. The client wants a number, not a brochure.

Step 5: Submit on time and follow up

Tender submissions are almost always rejected if late, even by one minute. Aim to submit a full day early, especially if you are uploading large files. Internet hiccups have killed many bids.

For residential quotes, the follow-up is what separates pros from amateurs:

  • 48 hours after sending the quote
  • One week later if no answer
  • Two weeks later, then move on

Most contractors send a quote and never follow up. Following up alone increases close rate by 30% to 40% in residential trades. The job often goes to the contractor who replied first and called twice.

Bid bonds in Ontario

If you are bidding on public projects in Ontario:

  • Mandatory on all publicly funded projects over $500,000, per the Ontario Construction Act
  • Penal sum: typically 5% to 10% of the bid amount
  • Cost: most surety companies offer bid bonds free for qualified contractors, or charge under $100
  • Submission: must be included with the bid package, not provided after winning

For private residential projects in Ontario, bid bonds are very rare. Some commercial private owners require them for projects above $100,000.

If you do not have a surety relationship, get one before you bid your first public job. Trying to set it up under deadline pressure is how new contractors miss tenders.

Common mistakes

  • Bidding everything: spreads you thin, drops your win rate, burns your nights
  • Pricing off the competition: they may be losing money too
  • No change order language: every contract should require written change orders only, signed by the client before work proceeds
  • Forgetting HST on the quote: customer disputes the 13% when the invoice arrives
  • Single-line scope: vague scope creates change-order arguments and disputes at handover
  • Late tender submission: an automatic rejection, no exceptions
  • No follow-up on residential quotes: kills 30% or more of winnable work
  • Mismatched paperwork: the bid form, the price summary, and the cover letter all need to show the same number. A typo on the price line has lost contracts that were otherwise the lowest bid.

Quick reference

  • Walk away from bids that do not match your budget, timeline, or capacity
  • Quote within 5 business days of the site visit
  • Price every line, then apply markup, never apply markup to a guess
  • Always state HST on the quote
  • Always state validity period (30 days)
  • Always follow up at 48 hours and 1 week
  • Submit tenders one day early
  • Get your bid bond relationship in place before you need it

For the legal framework on tendering and the 10% holdback rules, the Ontario Construction Act on Ontario.ca is the source of truth.

For the credentials side (general contractor licensing requirements by municipality), see General Contractor Licence Ontario and WSIB Clearance Certificate Ontario.

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