Build a garage

Attached, detached or workshop garage: siting, slab, framing, fire safety, heating, ventilation, electrical and EV charging.

Limit

Large openings, fire separations, loads, heating and electrical work often require permits and professional design.

Project types

  • Attached
  • Detached
  • Carport
  • Single
  • Double
  • Workshop
  • Room or dwelling above

Scope to coordinate

  • Setbacks, height, area, access and drainage
  • Turning radius, slope, snow and door threshold
  • Monolithic slab, foundation or piles
  • Drainage, insulation, vapour control and under-slab conduits
  • Headers, braced walls, trusses and overhead storage
  • Garage-house separation and CO protection
  • Heating, ventilation, lighting, tools and EV charger
  • Door, opener, seals, corrosion and maintenance

Critical controls

  • Validate use and siting before buying a plan.
  • Inspect base, reinforcement, anchors and conduits before concrete.
  • Never alter trusses or load attic storage without documented capacity.
  • Test door, detection, ventilation and equipment before use.

Potential participants

  • Municipality
  • Surveyor as required for siting
  • Engineer for soil, structure or large doors as warranted
  • Concrete/framing contractor
  • Authorized electrical and heating/ventilation specialists
Common method

Six phases with project-specific application

1
Feasibility and diagnosis Confirm constraints before committing to the project.
Application to this project: Use, siting, access and permits

Work and decisions

  • Define the need, future use, budget limits and performance target.
  • Survey the existing building or site, services, water, access and known risks.
  • Check zoning, permits, easements, environment and required professionals.
  • Separate confirmed facts, assumptions and unknowns in a dated register.

Hold points and controls

  • No irreversible purchase or contract before confirming major constraints.
  • A map, nearby borehole or verbal opinion does not replace project-specific verification.

Records to keep

  • Baseline surveys and photos
  • Authority responses
  • Risk and assumption register
2
Design, coordination and budget Turn needs into measurable coordinated scope.
Application to this project: Soil, slab, drainage and interfaces

Work and decisions

  • Coordinate architecture, structure, enclosure, plumbing, electrical, ventilation and drainage.
  • Select products and quality levels with acceptable alternatives.
  • Build a trade budget including fees, permits, tax, contingency and financing.
  • Create a schedule with dependencies, procurement and inspections.

Hold points and controls

  • Review drawings and interfaces before tender.
  • Do not compare prices without common scope and explicit exclusions.

Records to keep

  • Coordinated drawings and details
  • Specifications and inclusion-exclusion matrix
  • Baseline budget and schedule
3
Permits, contracts and mobilization Clearly assign approvals, responsibilities and protections.
Application to this project: Contracts, door, structure and procurement

Work and decisions

  • Submit required documents and track permit conditions.
  • Verify licences, insurance, references, subcontractors and capacity.
  • Define payments, changes, holdbacks, warranties and closeout deliverables.
  • Plan safety, occupant, neighbour, water, dust and access protection.

Hold points and controls

  • No start without applicable approvals and issued-for-construction documents.
  • No verbal change without written scope, cost and time.

Records to keep

  • Permits and conditions
  • Contract and appendices
  • Quality, safety and inspection plan
4
Concealed work and hold points Control elements that are difficult to correct after concealment.
Application to this project: Concrete, framing and concealed work

Work and decisions

  • Inspect soil, excavation, reinforcement, anchors, drainage and conduits before concrete or backfill.
  • Verify load paths, connections, bracing and temporary shoring.
  • Coordinate rough systems and penetrations before insulation or drywall.
  • Photograph each concealed element with location and scale.

Hold points and controls

  • No concealment without planned inspection and resolved deviations.
  • Stop immediately for unexpected water, soil, bearing or material.

Records to keep

  • Inspection and test reports
  • Pre-concealment photos
  • As-built record of concealed work
5
Enclosure, systems and commissioning Make the building watertight, functional, balanced and testable.
Application to this project: Enclosure, fire, mechanical and electrical

Work and decisions

  • Verify continuity of water, air, insulation and flashing layers.
  • Test plumbing, drainage, electrical, heating, ventilation, controls and safety.
  • Complete balancing, settings, leakage tests and corrections.
  • Protect sensitive materials until temperature and humidity are suitable.

Hold points and controls

  • Approve mock-ups and critical details before repetition.
  • No equipment acceptance without commissioning and service access.

Records to keep

  • Commissioning reports
  • Product data and settings
  • Equipment and serial number list
6
Closeout, warranties and follow-up Deliver documented maintainable work with seasonal follow-up.
Application to this project: Closeout, maintenance and load restrictions

Work and decisions

  • Inspect by space and system with photos, owner and due date.
  • Obtain closed permits, as-builts, manuals, warranties and training.
  • Reconcile budget, changes, credits, holdbacks and final balance.
  • Plan maintenance, warranty review and inspection after rain, freeze or heating season.

Hold points and controls

  • No acceptance without dated deficiencies and critical deliverables.
  • Keep an exported copy of the file outside the browser.

Records to keep

  • Deficiency list
  • Closeout file
  • Maintenance and warranty schedule
Concept quantities

Preliminary garage calculator

Results compare options; they do not size the structure or authorize a concrete order.

Related tools

Always confirm applicable permits, professions, insurance and code editions.

Garage deep dive

Build a durable, dry and usable garage

Important: The existing calculator compares options; it does not size foundation, structure or drainage.

Scenarios to compare

  • 12×20: small vehicle/workshop; verify clearances, storage and door before locking size.
  • 20×20 or 24×24: two vehicles only if circulation, doors, storage and equipment remain realistic.
  • 24×30 and larger: program, structure, drainage, heating and budget change quickly.

Dry winter garage

  • Site and slab grading must keep water from returning toward the building or door.
  • Do not make a heated garage simply 'airtight': control humidity, ventilation, separation from the house and condensation.
  • Salt, snowmelt and wet vehicles demand drainage, durable materials and maintenance.

Construction record

  • Photograph foundation, reinforcement, drains, anchors, air barrier, flashings and systems before covering.
  • Keep permits, plans, reports, invoices, warranties and equipment models.
Before you decide

Garage: slab, size and permit checks

Garage budgets depend on siting, excavation, drainage, access and overhead doors, not just floor area.

Practical checks

  • Confirm permitted dimensions
  • Check soil and grading
  • Budget foundation, door and utilities separately

Common question

Do attached and detached garages follow identical rules?

Not necessarily. Ask the municipality about requirements for the specific site.

Site prices and assistance programs require independent current-source checks; planning tools do not replace permits or professional quotes.