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Serving the Town of Cobourg (Northumberland County)
Modular Homes & Garden Suites in Cobourg, Ontario
Factory-direct modular homes and backyard suites for the Town of Cobourg — the Lake Ontario heritage town in Northumberland County, Eastern Ontario. Cobourg's new Comprehensive Zoning By-law 066-2025 permits an additional residential unit as-of-right, including a detached suite in your backyard — and the by-law expressly names a modular home on a permanent foundation as an eligible detached unit. Here's what the by-law allows, what it costs, and the rules that apply.
What you can build in Cobourg
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 Cobourg'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 Cobourg 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? (Cobourg lots typically allow up to ~700 sq ft)
Cobourg caps a detached backyard suite at 50% of your home’s gross floor area (and no more than half the rear yard), up to 4.5 m tall (§4.3.3). Most town lots are on full municipal services and qualify. Enter your address for the specifics. Your exact lot may allow more or less — get the real number for your address in seconds.
Check your exact Cobourg address →Can you put a garden suite (ADU) in your Cobourg backyard?
Often, yes — Cobourg permits a detached Additional Residential Unit on most serviced residential lots. The specifics, from Town of Cobourg Comprehensive Zoning By-law 066-2025, §4.3 — Additional Residential Units (passed December 17, 2025):
| Max size | A detached backyard suite may be up to 50% of your main home’s gross floor area — and no more than half your rear yard (§4.3.3.d). There’s no fixed m² cap. A unit inside the house is also capped at 50% of the home’s floor area. |
|---|---|
| Where it goes | Inside the house OR in a detached accessory building in the rear or side yard (never the front). Up to two additional units per lot — at most one of them detached (§4.3.1). |
| Height & setbacks | Detached suite up to 4.5 m (≈15 ft) — 8 m only above a garage on a laneway lot; at least 4.5 m from the house, 1.0 m (≈3 ft) from the rear lot line and 1.2 m (≈4 ft) from the interior side, within 40 m of the access street. No basement (§4.3.3). |
| Parking | 1 space per unit; the second unit’s space may be tandem in the driveway (§5.4) |
| Servicing | Where municipal water & sewer are available — essentially all of built-up Cobourg — the house and suite must connect to them (§4.3.1.d), so a typical town lot qualifies. A rare unserviced lot needs a private well+septic capacity confirmation. |
| Conservation | Ganaraska Region Conservation Authority (GRCA). No ARU is permitted in the Environmental Constraint (EC) Zone or a mapped floodplain near Cobourg Creek or the Lake Ontario shoreline (§4.3.1.e). |
Getting your building permit in Cobourg
An eligible lot still needs a building permit before anything is delivered. Here's how Cobourg's process actually works — verified against the Cobourg building department's own pages.
How do you apply for an ADU building permit in Cobourg?
Through Cloudpermit (online) — Town of Cobourg Building Division, 55 King St W, 905-372-1005. Cobourg accepts building-permit applications through Cloudpermit (online); the current fees are calculated at application. Zoning/ARU questions go to the Development Division (905-372-1005 / planninginfo@cobourg.ca). Confirm the current process and fees on the Town's Building Permits page before applying. Cobourg's building-permit page ↗
- Confirm zoning — a detached additional residential unit is as-of-right under Comprehensive Zoning By-law 066-2025 §4.3 (up to 50% of your home's gross floor area, 4.5 m tall, 4.5 m from the house, 1.0 m rear / 1.2 m side, in a rear/side yard, up to 2 units per lot / 1 detached). It is NOT permitted in the Environmental Constraint (EC) Zone or a mapped floodplain, or on a lot with shared housing / a B&B / a group home.
- Servicing: where municipal water and sewer are available (essentially all of built-up Cobourg) the suite must connect to them (§4.3.1.d) — confirm the plumbing connections. On a rare unserviced fringe lot, demonstrate private well and septic capacity for the added unit (septic is permitted directly by the County of Northumberland).
- If the lot is near Cobourg Creek or the Lake Ontario shoreline in a Ganaraska Region Conservation Authority (GRCA) mapped floodplain or hazard, obtain GRCA permission first — an ARU is not permitted in those areas.
- Retain a qualified BCIN designer for the Ontario Building Code construction drawings.
- Submit the building-permit application through Cloudpermit with the drawings and fees; respond to any review comments.
- Book building inspections through construction, plus a separate ESA electrical inspection, to occupancy.
What does a Cobourg ADU permit application need?
- Application for a Permit to Construct or Demolish + Schedule 1 Designer Information (BCIN) on the drawings
- Site plan showing property lines, all structures, the distance from the main dwelling to the suite, and the parking
- Full construction drawings — foundation plan, floor plans, elevations, and cross-sections
- Confirmation the suite connects to municipal water and sewer (serviced lot), or a private well+septic capacity demonstration (rare unserviced lot)
- GRCA permit or written consent where a floodplain / hazard overlay applies to the lot
How much does an ADU building permit cost in Cobourg?
The big saving is development charges: a qualifying additional residential unit is EXEMPT under Bill 23, versus about $40,479 (Existing Urban Service Area) or $54,940 (Cobourg East Community Service Area) that a new single/semi-detached house pays per the Town's 2026 Development Charges schedule (DC By-law 001-2022). The building-permit fee for a Group C dwelling is about $1,965 for a suite under 1,200 sq ft (or about $1.63 per sq ft above that), per the Town's published Building Permit Fee schedule (By-law 103-2015). Plumbing permit fees are set by the County of Northumberland (about $100–$165 base + $19 per fixture, 2026), and septic permits on an unserviced lot are paid directly to the County. All figures are estimates — confirm with the Building Division (905-372-1005).
| New detached ARU — building permit | ≈ $1,965 for a suite under 1,200 sq ft, or ≈ $1.63 per sq ft above (Town of Cobourg Building Permit Fee schedule, By-law 103-2015) |
|---|---|
| Plumbing permit (set by the County of Northumberland) | ≈ $100–$165 base + $19 per fixture (2026) |
| Development charges | EXEMPT for a qualifying ARU (Bill 23) — versus ≈ $40,479 (Existing Urban Service Area) or ≈ $54,940 (Cobourg East) for a new single/semi-detached house (2026) |
A qualifying additional residential unit is EXEMPT from development charges under the Development Charges Act (Bill 23) — a saving of roughly $40,479 (Existing Urban Service Area) or $54,940 (Cobourg East Community Service Area) versus a new single/semi-detached house, per the Town's 2026 DC schedule. Confirm the exemption for your project with the Building Division.
How long does an ADU building permit take in Cobourg?
Ontario's Building Code requires a decision on a complete house-class application within 10 business days. A house-class building permit is reviewed within the legislated 10 business days once a complete application is submitted (allow a little longer for a larger or more complex proposal). A GRCA hazard approval, where the lot needs one near Cobourg Creek or the lakeshore, can add time before the permit is issued.
Registration: Cobourg does not publish a separate ongoing ADU registration or licensing fee — the building permit through Cloudpermit is the approval. Confirm with the Building Division.
Worth knowing before you apply
- The biggest number is a saving: a qualifying ARU is EXEMPT from development charges under Bill 23 — roughly $40,479 (urban) or $54,940 (Cobourg East) that a new house would pay (2026 DC schedule).
- Cobourg takes building permits through Cloudpermit (online). The building-permit fee for a suite is about $1,965 flat under 1,200 sq ft (or ≈ $1.63/sq ft above), per the Town's published Building Permit Fee schedule (By-law 103-2015).
- Plumbing permit fees are set by the County of Northumberland (≈ $100–$165 base + $19/fixture), and a septic permit on an unserviced lot is paid directly to the County.
- An ARU is not permitted in the Environmental Constraint (EC) Zone or a GRCA-mapped floodplain — near Cobourg Creek or the Lake Ontario shoreline, get GRCA sign-off first.
- All drawings need a qualified BCIN designer (Schedule 1), and a separate ESA electrical inspection is required.
Fees and timelines are estimates from Cobourg's published schedules, verified July 14, 2026. Rates and processes change — always confirm current requirements with the building department before you apply.
Grants & financing in Cobourg
Development-charge relief for additional units — Under the Development Charges Act (Bill 23), a qualifying additional residential unit ancillary to your home is generally exempt from municipal development charges — confirm the current treatment with the Town for your project.
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 →
Cobourg modular homes — FAQ
Can you build a garden suite / ADU in Cobourg?
Yes — Cobourg’s new Zoning By-law 066-2025 (§4.3) permits an additional residential unit as-of-right, and it may be in a detached accessory building in your backyard. A detached suite is capped at 50% of your home’s gross floor area, is up to 4.5 m tall, needs 1 parking space, and requires a building permit. The by-law expressly allows the detached unit to be a modular home.
How big can a backyard suite be in Cobourg?
A detached backyard suite may be up to 50% of your home’s gross floor area, and it can’t cover more than half of your rear yard (§4.3.3.d) — there’s no fixed maximum m². It’s limited to 4.5 m in height (8 m only above a garage on a laneway lot) and must sit at least 4.5 m from your house. Enter your address for the specifics.
Can you build an ADU on well and septic in Cobourg?
Where municipal water and sewer are available — which is essentially all of built-up Cobourg — the by-law requires the house and suite to connect to them (§4.3.1.d), so town lots qualify outright. On a rare unserviced fringe lot, a private well+septic system can work with a septic-capacity confirmation.
Can you put a modular home in Cobourg, Ontario?
Yes. Cobourg’s Zoning By-law 066-2025 expressly defines a detached additional residential unit as one that “can be considered a modular home dwelling” on a permanent foundation (a mobile home or trailer doesn’t qualify). A modular home is also legal residential housing under the Ontario Building Code as the principal dwelling on land you own.
How much does a modular home or backyard suite cost in Cobourg?
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 Cobourg?
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 Town of Cobourg Comprehensive Zoning By-law 066-2025, §4.3 — Additional Residential Units (passed December 17, 2025); verified by Modular Homes 400 and reviewed by James Clarke, REALTOR®. Always confirm current requirements with the City of Cobourg before you build.