A detached garage in Ottawa typically costs $25,000 to $70,000 or more, depending on size, foundation type, and finish level. A basic single-car garage (roughly 12×20) starts around $25,000–$35,000; a standard double (20×20 to 22×22) runs $40,000–$60,000; and a larger 24×24 with a heated slab, insulation, or a loft climbs past $70,000. Because a detached garage is a stand-alone structure, it needs its own foundation, roof, siding, and electrical service — costs that scale with square footage but also with choices like frost-wall versus slab-on-grade, door quality, and whether you finish the in...
Detached garages in Ottawa run roughly $110 to $200 per square foot, with smaller garages costing more per foot because fixed costs (foundation setup, roof, door, service connection) spread over less area. Here's a size-based breakdown for standard construction — poured or block foundation, framed walls, asphalt-shingle roof, one insulated overhead door, and basic electrical: • 12×20 single car (240 sq ft) — $25,000–$38,000 • 14×24 single car with storage (336 sq ft) — $32,000–$46,000 • 20×20 double car (400 sq ft) — $40,000–$56,000 • 22×22 double car (484 sq ft) — $46,000–$64,000 • 24×24 double car (576 sq ft) — $52,000–$72,000 • 24×28 or larger with loft/workshop (672+ sq ft) — $65,000–$95,000+ Add heating, a finished interior, a second-storey loft, or premium siding and these numbers rise quickly. The lower end assumes simple, flat, accessible lots; the upper end reflects difficult access, deeper foundations, and upgraded finishes.
Base quotes typically include the foundation, framing, roof, exterior cladding, one overhead door with opener, an entry door, and basic wiring with a few outlets and lights. They usually exclude heating systems, interior drywall and insulation, epoxy flooring, a subpanel, EV charging, and site work like grading, a new driveway apron, or tree removal. Always confirm exactly what a quote covers — the gap between a shell and a finished garage can be $10,000–$25,000.
The foundation is the most consequential — and variable — cost on a detached garage, because Ottawa's deep frost line dictates how you build below grade. Three common approaches: • Slab-on-grade with thickened edge (floating slab) — cheapest, $8,000–$16,000, suitable for unheated garages on stable soil, but more prone to frost movement if drainage is poor • Frost-wall foundation (footings below frost, poured or block wall, slab inside) — $14,000–$26,000, the standard for heated garages and anything you want to last decades without heaving • Full foundation with basement or crawlspace — rare for garages, $25,000+, only for special uses Given our climate, most homeowners building a garage they'll heat or keep long-term choose a frost-wall foundation. A floating slab can work for a cold storage garage but demands excellent drainage and gravel base — cut corners and freeze/thaw cycles will crack it. Soil conditions matter too: clay-heavy or high-water-table lots in some suburban areas may need extra excavation or engineered fill.
Beyond size and foundation, several choices move the number significantly. Understanding them helps you build a realistic budget rather than anchoring on a headline price. • Foundation type and soil/drainage conditions (biggest swing after size) • Site access — tight urban lots limit equipment and add labour • Overhead door quality — a basic non-insulated door versus an insulated, windowed, quiet-belt-drive setup • Roof style and pitch — a simple gable is cheapest; a hip roof or a loft-ready truss system costs more • Exterior finish — vinyl siding is economical; brick, board-and-batten, or stone to match the house costs more • Electrical scope — a few outlets versus a subpanel, workshop circuits, and EV charging • Heating and insulation — a heated, insulated garage adds $5,000–$15,000 • Site work — grading, driveway apron, drainage, and any tree or shed removal
If you want a garage usable year-round in Ottawa — a workshop, gym, or hobby space — plan for insulation, drywall, and a heat source from the start. Spray foam or batt insulation with drywall runs $6–$12 per square foot; a gas or electric unit heater adds $1,500–$5,000; and a ductless mini-split, popular for its efficiency, is another common choice. Building this in from day one is far cheaper than retrofitting a finished, uninsulated shell later.
You almost always need a City of Ottawa building permit for a detached garage, and it must comply with zoning rules on setbacks, lot coverage, and maximum size or height for accessory structures. Very small structures may fall under a size threshold, but most functional garages exceed it — don't assume you're exempt. The permit review covers the foundation, structural design, and how the garage sits relative to lot lines and existing buildings. Zoning is where projects most often stall: side- and rear-yard setbacks, lot coverage limits, and easements can shrink or block the garage you envisioned, especially on tighter lots in Centretown or older Nepean neighbourhoods. Confirm your zoning envelope before drawing plans. Electrical work requires an ESA permit and inspection separate from the building permit. Budget for permit fees and a few weeks of review time in your schedule.
A double garage costs more upfront but almost always delivers better value per square foot and stronger resale appeal than a single. Because fixed costs — foundation setup, roof structure, service connection — don't double when you go from a single to a double, the incremental cost of the extra bay is modest relative to the added space. In most Ottawa neighbourhoods a double garage is also what buyers expect. Go single if your lot, budget, or zoning coverage limits force it, or if you genuinely need only one bay plus modest storage. Go double (or larger) if you want a workshop, room for a growing household's second vehicle, or storage for lawn and winter equipment. If you're torn, size the foundation and slab for the bigger footprint even if you finish less now — expanding later is far more costly than pouring a slightly larger slab up front.
The most common detached-garage mistake in Ottawa is choosing a floating slab to save money on a garage you later decide to heat, then watching it crack from frost movement. Match the foundation to how you'll actually use the space, and build for the long term in our climate. Other pitfalls: • Skipping the zoning check and designing a garage that breaches setbacks or coverage limits • Under-sizing electrical, so there's no capacity for a heater, workshop, or EV charger • Ignoring drainage and grading, letting meltwater pool against the foundation • Comparing quotes that include different scopes — a shell versus a finished garage • Hiring a shed builder for a full structure requiring foundation, roofing, and code-compliant electrical
Choose a contractor who regularly builds full structures — foundation, framing, roofing, and code-compliant electrical — not just sheds or decks. Ask to see recent detached garages they've built in the Ottawa area, and confirm they handle the building permit, coordinate the ESA electrical inspection, and carry liability insurance plus WSIB coverage. A detailed, line-itemed quote lets you compare bids fairly and spot what's excluded. Get three quotes and read the scopes closely; the cheapest number often hides an unfinished shell, a floating slab where a frost wall belongs, or excluded site work. Tie payments to milestones — permit, foundation, framing, completion — rather than a large deposit, and verify the contractor's licensing and references before signing. A well-vetted contractor is the difference between a garage that lasts 40 years and one that cracks in five.
Most detached garages cost $25,000 to $70,000 or more. A basic single-car (12×20) runs $25,000–$38,000, a standard double (20×20) runs $40,000–$56,000, and a larger 24×24 with upgrades exceeds $70,000. Expect $110–$200 per square foot, with smaller garages costing more per foot because fixed costs like the foundation, roof, and door spread over less area.
A single-car detached garage in Ottawa typically costs $25,000 to $46,000 depending on size and finish. A minimal 12×20 shell with a slab, basic door, and simple wiring sits at the low end, while a 14×24 with storage, a frost-wall foundation, and better finishes climbs higher. Heating and interior finishing add several thousand more.
A double-car detached garage generally costs $40,000 to $72,000. A 20×20 falls around $40,000–$56,000, while a 24×24 with a frost-wall foundation, insulated doors, and upgraded finishes reaches $52,000–$72,000. Because fixed costs don't double when you add a second bay, a double often delivers better value per square foot than a single.
It depends on use. A floating slab-on-grade ($8,000–$16,000) works for an unheated cold-storage garage on well-drained soil, but a frost-wall foundation with footings below the frost line ($14,000–$26,000) is standard for heated garages and anything meant to last decades. Ottawa's deep frost and freeze/thaw cycles will crack an under-built slab, so match the foundation to how you'll use the space.
Yes, in almost all cases you need a City of Ottawa building permit, and the garage must comply with zoning setbacks, lot coverage, and height limits for accessory structures. Electrical work requires a separate ESA permit and inspection. Confirm your zoning envelope before designing, since setbacks and coverage limits can shrink or block the garage on tighter lots.
Making a garage usable year-round typically adds $5,000 to $15,000. Insulation with drywall runs $6–$12 per square foot, a gas or electric unit heater adds $1,500–$5,000, and a ductless mini-split is a popular efficient option. Building insulation and heating in from the start is far cheaper than retrofitting a finished uninsulated shell later.
A single garage is cheaper in absolute dollars, but a double costs less per square foot because the foundation setup, roof, and service connection don't double when you add a bay. If there's any chance you'll want the extra space, pouring a larger slab up front is far cheaper than expanding later. In most Ottawa neighbourhoods a double also has stronger resale appeal.
A standard detached garage takes roughly four to eight weeks of construction once permits are issued, longer with interior finishing or difficult site conditions. Permit review adds lead time before work begins, and weather-dependent phases like excavation and concrete pours are best scheduled for spring through fall to avoid cold-weather surcharges.