Modular vs site-built at a glance
Modular X builds both. This comparison is written to help you pick — not to sell you on one path. Neither method is universally better; each is better in specific situations.
| Modular | Site-built | |
|---|---|---|
| Timeline | Factory + site prep run in parallel. Total build often 4–6 months. | Sequential trades on site. Typically 6–9+ months. |
| Price predictability | Factory costs are fixed-price at contract; weather doesn't affect the module. | Weather, labour availability, and material timing introduce variance. |
| Site disruption | Days of crane set + connection work; your yard is not a job site for months. | Months of trades, deliveries, and debris in your backyard. |
| Customization | Wide selection within transportable module dimensions. | Wins on unusual lots, non-rectangular footprints, and one-off designs. |
| Access constraints | Requires crane and truck access. Tight lots can rule this out. | Trades can work in almost any accessible yard. |
| Code review | Module certified to the Ontario Building Code at the factory under CSA A277; foundation and connections inspected on site. | Every stage inspected on site by the municipality. |
Both delivery methods, and the install work that follows, are described on our services page.
CSA A277 factory certification, in plain English
A common concern is that modular units skip inspection. They don't. Modular units built for Ontario are certified under CSA A277, which requires a third-party certifying agency to inspect the factory's quality systems and to inspect each module during construction — the same code checks a municipal inspector would perform, but done at the factory before the module leaves.
Municipalities across the GTA — including Mississauga and Toronto — accept CSA A277 certification documentation as proof that the module complies with the Ontario Building Code. On-site inspections still cover the foundation, connections, and site work.
When we recommend each
We recommend modular when:
- You have a rectangular backyard with reasonable crane access.
- You want a fixed price and a short site-disruption window.
- Rental income timing matters — the schedule advantage is real revenue.
- You're using one of the pre-approved layouts (see our plans catalogue).
We recommend site-built when:
- Your lot has no crane access, or overhead wires block a set.
- You want a distinctive architectural design that doesn't fit modular dimensions.
- The lot has unusual geometry, grade change, or heritage constraints.
The right answer for your specific yard comes out of a feasibility review — that's step one either way. Municipal rules also shape the call: the pre-approved route in Mississauga's garden suite program suits modular well, while narrow downtown lots behind a lane — see what Toronto allows for laneway suites — more often force a site-built or panelized answer.
Frequently asked questions
Keep reading
Sources
- CSA A277 — Procedure for factory certification of buildings
- Ontario Building Code (O. Reg. 332/12)
- City of Mississauga — Additional residential units
- City of Toronto — Garden suites
Municipal rules, fees, and programs change. Confirm current requirements with the city at application. Modular X provides exact pricing only after a site-specific feasibility review.
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.