Home/Modular Homes by City/Thunder Bay
Serving Thunder Bay & Northwestern Ontario
Modular Homes in Thunder Bay, Ontario
Factory-direct modular homes and backyard suites for the City of Thunder Bay — including Fort William, Port Arthur, Westfort, and Current River. Thunder Bay's zoning by-law calls a detached suite a “backyard home” and permits it as-of-right in the urban neighbourhoods. Here's what it allows, what it costs, and the rules that apply.
What you can build in Thunder Bay
Full modular homes — from $175,696. 29 models from 560 to 1,405 sq ft, 1–3 bedrooms — factory-built to the Ontario Building Code and set on a permanent foundation (a real, permanent house, not a “trailer”).
Backyard suites (ADUs) — from $96,244. 7 compact models built for garden-suite and in-law-suite use, sized to fit what Thunder Bay's by-law allows.
All homes are CSA-certified (A277 modular / Z240MH manufactured), finished in the factory, and delivered ready for foundation and hook-up. What's the difference between modular, manufactured, and mobile? →
Find your backyard suite — 3 quick questions
We'll narrow the models that fit a typical Thunder Bay backyard allowance to the ones that fit your life. No email needed.
1 · Who's it for?
2 · What layout?
3 · What size feels right? (Thunder Bay lots typically allow up to ~1,076 sq ft)
Thunder Bay’s “backyard home” floor area is the greater of 50 m² (≈538 sq ft) or 40% of your home, capped at 100 m² (≈1,076 sq ft) across all detached accessory buildings. Your exact lot may allow more or less — get the real number for your address in seconds.
Check your exact Thunder Bay address →Can you put a garden suite (ADU) in your Thunder Bay backyard?
Often, yes — Thunder Bay permits a detached Additional Residential Unit on most serviced residential lots. The specifics, from City of Thunder Bay Zoning By-law 1-2022 §12.2 + Table 3.2.2 (Backyard Homes):
| Max size | Greater of 50 m² (≈538 sq ft) or 40% of your home; all accessory buildings combined capped at 100 m² (≈1,076 sq ft) |
|---|---|
| Max height | 4.6 m (≈15 ft), max 3.2 m wall height; no basement unit |
| Setbacks | 0.6 m (≈2 ft) rear · 1.5 m interior side (0.6 m if ≥20 m from the front) · 2.0 m (≈7 ft) from the main house |
| Units per lot | One backyard home per detached house (up to ~3 homes total) |
| Parking | 1 space per home |
| Servicing | Municipal water + sewer REQUIRED — rural and rural-settlement lots aren’t eligible as-of-right |
| Conservation | Lakehead Region Conservation Authority (LRCA); a 1.5 m walkway from the street is required |
Grants & financing in Thunder Bay
See every program → Ontario ADU Grants Directory
A modular or prefab home on a permanent foundation is financed like any house. CMHC Prefab Plus allows an insured mortgage with as little as 5% down on the first $500,000, with construction funds released in stages. How modular home financing works →
Thinking of the suite as a rental? Run the numbers →
Thunder Bay modular homes — FAQ
Can you build a backyard home in Thunder Bay?
Yes — in the urban neighbourhoods (Fort William, Port Arthur and the city’s residential zones), Thunder Bay permits a detached “backyard home” as-of-right, subject to the size, height, and setback rules and full municipal servicing.
How big can a backyard home be in Thunder Bay?
The floor area is the greater of 50 m² (≈538 sq ft) or 40% of your main home, with all detached accessory buildings capped together at 100 m² (≈1,076 sq ft). Max 4.6 m tall, no basement.
Can you put a modular home in Thunder Bay?
Yes. On land you own, a modular home on a permanent foundation is legal residential housing under the Ontario Building Code throughout Thunder Bay, subject to standard zoning and permits.
How much does a modular home or backyard suite cost in Thunder Bay?
Modular home models start at $175,696 and run to about $338,000 for the largest layouts; backyard ADU models start at $96,244. Site work, foundation, delivery, and permits are additional.
Can I get a mortgage on a modular home in Thunder Bay?
Yes — on a permanent foundation it is financed as real property, including via CMHC Prefab Plus (5% down on the first $500,000).
Local rules summarized from City of Thunder Bay Zoning By-law 1-2022 §12.2 + Table 3.2.2 (Backyard Homes); verified by Modular Homes 400 and reviewed by James Clarke, REALTOR®. Always confirm current requirements with the City of Thunder Bay before you build.