Short answer: modular construction builds a home or building as three-dimensional modules in a factory, then ships, cranes and connects them on a foundation at the site. The Government of Ontario says it can save construction time, avoid weather delays and produce less waste, and the federal agency Build Canada Homes now prioritizes factory-built and modular housing.
Key takeaways
| Question | Short answer | Source |
|---|---|---|
| What is it? | Three-dimensional modules built off-site, then assembled on a foundation | Ontario |
| Modular vs prefab | All modular is prefab; not all prefab is modular | Ontario |
| Federal push | Build Canada Homes: six sites for 4,000 factory-built homes, capacity up to 45,000 units | Prime Minister of Canada |
| Toronto example | 321 Dovercourt Road: 44 studios, five months from design to installation | Ontario |
| Supplier call | Build Canada Homes RFI on modern methods of construction, February 4, 2026 | Canada.ca |
| Code | Same Building Code as site-built; factory (CSA A277) plus on-site inspections | Ontario |
What modular construction is
Ontario defines a modular house as one built using one or more prefabricated, three-dimensional components or modules, constructed partially or completely off-site in a manufacturing facility, then transported to a property and assembled there. Wiring and plumbing can be installed in the modules before they leave the plant (Ontario — Building a modular house).
Prefabricated construction is the broader term. Panelized systems ship flat wall panels; modular systems ship finished three-dimensional boxes. Build Canada Homes groups modular, panelized and prefabricated systems together as modern methods of construction (Canada.ca).
How a modular building goes up
- Design and permit. The design is finalized early, and a building permit covers both the factory-built modules and the site work.
- Factory build. Modules move along an assembly line between trades in a climate-controlled plant.
- Site work at the same time. Many municipalities let excavation and foundation work start while modules are built.
- Delivery and set. Modules travel by flatbed truck and are set on the foundation by crane, then fastened together and anchored.
- Finishing and inspection. Hook-ups and finishes are completed, and the municipality inspects before occupancy.
Source: Ontario — Building a modular house.
Benefits and trade-offs
Ontario lists these benefits: a predictable timeline in a controlled environment, less exposure to weather and to labour shortages, saved construction time, energy efficiency, and fewer carbon emissions and less waste than traditional on-site construction. The trade-offs it names: the design must be locked early, transport distance adds cost and time, and modules can occasionally be damaged in transit.
Modular housing in Canada
At the launch of Build Canada Homes on September 14, 2025, the Prime Minister said the agency would prioritize factory-built, modular and mass timber construction, and develop six sites to build 4,000 factory-built homes on federal lands, with capacity for up to 45,000 units. In January 2026 the government said Requests for Qualifications had been issued for Direct Build sites in Dartmouth, Longueuil, Ottawa, Toronto, Winnipeg and Edmonton (Canada.ca).
On February 4, 2026, Build Canada Homes launched a Request for Information to engage Canadian firms in modular, panelized and prefabricated systems (Canada.ca).
Modular housing in Toronto
Ontario's guide highlights 321 Dovercourt Road in Toronto, a three-storey modular building with 44 studio apartments built under the City of Toronto's Modular Housing Initiative. The modules were made in Grimsby, and the whole process from design to installation took five months; the building opened on January 28, 2021 (Ontario).
Codes and inspections
Modular buildings must meet the same Ontario Building Code as site-built ones. In a factory certified to CSA A277, accredited inspectors check modules in the plant; otherwise the municipality arranges inspection. On site, building officials inspect the foundation, grading, module installation and hook-ups before issuing occupancy. More detail: what a modular home is in Ontario.
Modular construction for backyard suites
The same method works at small scale. A garden or laneway suite can be one or more modules craned into the backyard, where zoning allows the unit and the lot has crane access. Under the Planning Act, eligible urban lots can have up to three residential units, one of which can be in an ancillary building. See modular vs site-built garden suites and how to choose a modular home builder in Ontario.
Where Modular X fits
Modular X designs, permits and builds garden and laneway suites in modules across the GTA. A feasibility check reviews zoning, access, trees and servicing before any design. Start with a lot feasibility check, or read the garden suites hub.
FAQs
Sources
- Government of Ontario — Building a modular house
- Prime Minister of Canada — Launch of Build Canada Homes (September 14, 2025)
- Canada.ca — Build Canada Homes: Thousands of homes in the pipeline (January 7, 2026)
- Canada.ca — Build Canada Homes RFI on modern methods of construction (February 4, 2026)
- Planning Act, R.S.O. 1990, c. P.13
Disclaimer: Figures cited are market estimates provided for information only and are not a quote. Municipal rules, fees, and programs change — always verify current requirements with your local authority. Modular X provides exact pricing only after a site-specific feasibility review.