Key takeaways
| Question | Short answer | Source |
|---|---|---|
| Parallel work | Factory construction and site preparation can run at the same time. | Build-method comparison |
| Factory certification | CSA A277 is a third-party certified factory quality system. | CSA A277 explanation |
| Site inspections | The municipality still inspects foundations and connections on site. | Factory and site inspection scope |
| Delivery access | Modular installation requires truck and crane access. | Choosing a build method |
| Site-built fit | Site-built can suit unusual footprints or lots where overhead wires block a crane set. | Site-built considerations |
What CSA A277 means
A277 is a third-party certified factory quality system. Modules are inspected in the factory to the Ontario Building Code; the foundation and connections are still inspected on site by the municipality. Modular X builds both ways — we are not a PDF reseller.
City catalogues are drawings only. The factory certification applies to factory-built modules Modular X can crane in when the lot allows. Review the available City drawings on our garden suite plans page, then start with the lot check to confirm which build path fits.
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.
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.
- Move-in timing matters — factory construction and site preparation can run in parallel.
- 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.
Where we build: Toronto, Mississauga, Brampton, Oakville, Etobicoke, Milton, and Burlington. Either delivery method is available across the GTA — the right one comes out of a lot review.
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.