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Complete Guide to Hiring an ADU Contractor

Finding, vetting, and working with contractors in Ontario

Why ADU Projects Need Special Expertise

ADU construction is different from regular renovations. Your contractor needs to understand:

Warning
General contractors without ADU experience often underestimate complexity, leading to cost overruns, failed inspections, and delays.

Step 1: Finding Potential Contractors

Where to Look

SourceProsCons
Referrals from friends/familyTrusted, real experienceLimited options
Municipal building deptThey see who does good workWon't give formal recommendations
Architectural firmsWork with qualified buildersMay be higher-end/expensive
HomeStars/HouzzReviews, portfoliosCan be manipulated
Google BusinessReviews, localMixed quality
Renovation contractors associationsVetted membersMembership ≠ quality

Questions to Ask When First Contacting

  • "Have you built ADUs or secondary suites before?"
  • "Can you provide references from ADU projects?"
  • "Are you familiar with [your municipality's] permit process?"
  • "Do you handle permits or do I need to?"
  • "What's your typical timeline for a project like mine?"
  • "Are you available to start within my timeframe?"

    • Red Flag: If they can't answer these confidently, keep looking.

    Step 2: Vetting Contractors (The Critical Step)

    2.1 Verify Licensing

    Ontario doesn't require a general contractor license, but trades need licenses:

    TradeLicense RequiredHow to Verify
    ElectricianYes - ESA licenseesa.safe.com
    PlumberYes - MunicipalContact municipality
    HVACYes - TSSA registrationtssa.org
    Gas FitterYes - TSSAtssa.org

    Ask: "Who does your electrical/plumbing work? Can I see their licenses?"

    2.2 Verify Insurance

    Required Insurance:

    TypeMinimum CoverageWhy You Need It
    General Liability$2,000,000Covers property damage, injuries
    WSIB CoverageActiveCovers worker injuries on your property

    How to Verify:

  • Ask for Certificate of Insurance
  • Call the insurance company to confirm it's active
  • Make sure YOUR ADDRESS is covered
  • Check expiration dates

    • CRITICAL: If a contractor doesn't have WSIB and a worker is injured on your property, YOU could be liable.

    2.3 Check References

    Get at least 3 references from ADU/secondary suite projects

    Questions for References:

  • "Was the project completed on time?"
  • "Was it completed on budget? Any surprises?"
  • "How did they handle problems that came up?"
  • "Did they pass all inspections on first try?"
  • "Would you hire them again?"
  • "Can I see the finished project?"

    • Visit a completed project if possible - see the quality firsthand.

    2.4 Review Past Work

    Ask for:

    Look for:

    2.5 Check Legal History

    Free Resources:

    Step 3: Getting Quotes

    3.1 How Many Quotes?

    Get at least 3 quotes from qualified contractors.

    3.2 What to Provide for Accurate Quotes

    Give each contractor the same information:

    3.3 Types of Quotes

    Quote TypeDescriptionRisk Level
    Fixed PriceSet total priceLow risk to you
    Cost PlusMaterials + labor + markup %Higher risk
    Time & MaterialsHourly rate + materialsHighest risk

    Recommendation: For ADUs, prefer fixed price quotes with detailed scope.

    3.4 What Should Be in a Quote

    Detailed Quote Includes:

    3.5 Analyzing Quotes

    Compare Apples to Apples:

    Beware of:

    Step 4: Red Flags to Watch For

    Immediate Disqualifiers

    ❌ No written contract - Never proceed without one

    ❌ Asks for large deposit - More than 10% upfront is risky

    ❌ Cash only - No paper trail, often no insurance

    ❌ No insurance/WSIB - You're exposed to liability

    ❌ Pressure to sign immediately - Legitimate contractors don't rush

    ❌ Won't provide references - What are they hiding?

    ❌ Wants YOU to pull permits - They're avoiding responsibility

    ❌ Quote is way below others - Either missing scope or will add later

    ❌ No physical address - Hard to find if problems arise

    ❌ Bad online reviews - Especially patterns of complaints

    Warning Signs During Project

    ⚠️ Constantly asking for more money

    ⚠️ Work quality doesn't match samples/promises

    ⚠️ Workers change frequently

    ⚠️ Missing deadlines without communication

    ⚠️ Not scheduling required inspections

    ⚠️ Cutting corners on materials

    ⚠️ Subcontractors don't seem qualified

    Step 5: The Contract

    5.1 Essential Contract Elements

    Your contract MUST include:

  • Full Legal Names & Addresses

    • - Your name and address

    - Contractor's legal business name and address

    - HST number

  • Detailed Scope of Work

    • - Specific description of ALL work included

    - Reference to drawings/specifications

    - List of exclusions

  • Price and Payment Terms

    • - Total contract price

    - Payment schedule tied to milestones

    - How change orders are handled

    - HST included or extra

  • Timeline

    • - Start date

    - Milestone dates

    - Completion date

    - Penalties for delays (if any)

  • Permits and Approvals

    • - Who obtains permits

    - Who pays for permits

    - Responsibility for passing inspections

  • Materials

    • - Specific products/brands

    - Allowances with dollar amounts

    - Who chooses alternates if unavailable

  • Change Order Process

    • - How changes are requested

    - How changes are priced

    - Required written approval

  • Insurance and Liability

    • - Contractor's insurance requirements

    - WSIB confirmation

    - Who's responsible for what

  • Warranty

    • - Warranty period (typically 1-2 years)

    - What's covered

    - How to make claims

  • Dispute Resolution

    • - How disputes are handled

    - Mediation/arbitration clause

  • Termination

    • - How either party can end contract

    - What happens to deposits/work completed

    5.2 Payment Schedule Guidelines

    Recommended Payment Structure:

    MilestonePaymentCumulative
    Contract signing10%10%
    Materials delivered20%30%
    Framing complete20%50%
    Rough-ins complete20%70%
    Drywall complete15%85%
    Final completion15%100%

    Key Rules:

    5.3 Ontario-Specific Requirements

    Consumer Protection Act Requirements:

    Tarion Warranty (New Home):

    Step 6: During Construction

    6.1 Communication

    Establish:

    Document Everything:

    6.2 Site Visits

    Regular visits help you:

    Respect:

    6.3 Handling Problems

    When Issues Arise:

  • Document the issue (photos, notes)
  • Communicate in writing
  • Reference contract terms
  • Give reasonable time to correct
  • Escalate if not resolved

    • Common Issues:

    6.4 Change Orders

    Any change from original scope:

  • Must be in writing
  • Include price impact
  • Include timeline impact
  • Signed by both parties BEFORE work

    • Track all changes - small ones add up quickly.

    Step 7: Project Completion

    7.1 Final Walkthrough

    Before final payment:

    7.2 Documentation to Receive

    Get from contractor:

    7.3 Warranty Period

    After completion:

    Contractor Interview Checklist

    Print this and use during contractor meetings:

    Basic Information

    Experience

    Licensing & Insurance

    Project Approach

    References Checked

    Overall Assessment

    Resources

    Verify Licenses

    Check Reputation

    Consumer Protection

    Industry Associations

    Hiring the right contractor is the most important decision in your ADU project. Take your time, do your research, and don't let price be the only factor.