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Serving the Town of Smiths Falls (Lanark County)
Modular Homes in Smiths Falls, Ontario
Factory-direct modular homes and backyard suites for the Town of Smiths Falls — the historic Rideau Canal town in Lanark County, Eastern Ontario. Smiths Falls' Comprehensive Zoning By-law 10375-2022 permits an additional residential unit as-of-right — including a detached suite in your backyard. Here's what the by-law allows, what it costs, and the rules that apply.
What you can build in Smiths Falls
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 Smiths Falls'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 Smiths Falls 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? (Smiths Falls lots typically allow up to ~700 sq ft)
Smiths Falls caps an additional residential unit at 40% of your home’s gross floor area (§4.2.6). Height and side setbacks follow your zone’s main-dwelling standards; the rear-yard setback is a minimum 1.2 m. 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 Smiths Falls address →Can you put a garden suite (ADU) in your Smiths Falls backyard?
Often, yes — Smiths Falls permits a detached Additional Residential Unit on most serviced residential lots. The specifics, from Town of Smiths Falls Comprehensive Zoning By-law 10375-2022, §4.2 — Additional Residential Units (Council adopted August 22, 2022):
| Max size | Up to 40% of the gross floor area of your main dwelling (no fixed m² cap). A basement unit may use the whole basement. |
|---|---|
| Where it goes | Inside the house OR in a detached accessory building/structure — a true backyard suite. Up to one interior unit plus one detached unit per lot (a maximum of two additional units). |
| Height & setbacks | Follow your zone’s main-dwelling standards, except a minimum 1.2 m (≈4 ft) rear-yard setback. The suite counts toward your zone’s maximum lot coverage — confirm the numbers for your specific zone. |
| Parking | 1 space per unit, shared with the main dwelling’s driveway (tandem allowed) — no new driveway may be created |
| Servicing | Permitted where adequate public OR private water and sanitary sewer are available (§4.2.4). Most of Smiths Falls is on full municipal water & sewer, so a typical town lot qualifies |
| Conservation | Rideau Valley Conservation Authority (RVCA) — a lot near the Rideau River / Canal, a wetland, or a mapped floodplain may need an RVCA permit |
Getting your building permit in Smiths Falls
An eligible lot still needs a building permit before anything is delivered. Here's how Smiths Falls's process actually works — verified against the Smiths Falls building department's own pages.
How do you apply for an ADU building permit in Smiths Falls?
Through Town of Smiths Falls — Building Services / Chief Building Official. Submit the Application to Construct or Demolish in person at Town Hall, by email to building@smithsfalls.ca, or online via the Town's Electronic Building Permit Application Portal. The Town clears 'applicable law' (Planning & Land Use, Public Works & Utilities, Fire, Building/CBO) internally on the owner's behalf. Electrical is a separate permit through the Electrical Safety Authority (1-877-372-7233). Smiths Falls's building-permit page ↗
- Confirm zoning — an additional residential unit (interior or detached) is as-of-right under Zoning By-law 10375-2022 §4.2 at up to 40% of your main dwelling's gross floor area; height and side setbacks follow your zone's main-dwelling standards (rear yard min 1.2 m)
- Retain a qualified BCIN designer for the Ontario Building Code Part 9 construction drawings + an SB-12 energy-efficiency compliance sheet
- If the lot is near the Rideau River/Canal, a wetland, or a mapped floodplain, obtain a Rideau Valley Conservation Authority (RVCA) approval
- Submit the Application to Construct or Demolish (in person / email building@smithsfalls.ca / online portal) with drawings and fees
- The Town clears applicable law internally (Planning, Public Works & Utilities, Fire, Building); respond to any plan-review comments and pay fees
- Book building inspections, and a separate ESA electrical inspection
What does a Smiths Falls ADU permit application need?
- Application to Construct or Demolish (permit application form) + Designer Information + SB-12 compliance sheet
- Site plan, foundation plan, floor plan, elevations, and section/detail drawings
- Lot grading / drainage information where the landscape changes
- RVCA approval where the lot is in a regulated floodplain / shoreline / wetland area
- Engineering design where required
How much does an ADU building permit cost in Smiths Falls?
Estimate for a ~700 sq ft detached suite worth roughly $150,000 of construction value: about $2,220 for the building permit (1.48% of construction value) plus about $2,220 for the plumbing/HVAC system permit (1.48%) — on the order of $4,400 in permit fees, plus a refundable residential driveway/parking security deposit and HST where applicable. The minimum permit fee is $75.25. Figures from the Town's 2026 Classes of Permits and Permit Fees (Schedule A to Building By-law 7917-2005, effective February 1, 2026, annually CPI-indexed to the Ottawa region) — confirm current-year figures and your project's construction value with Building Services. A qualifying ADU is EXEMPT from development charges under Bill 23 (see below).
| Building permit — construction value | 1.48% of construction value (a ~$150,000 suite ≈ $2,220); minimum permit fee $75.25 (2026 fee schedule) |
|---|---|
| Plumbing / HVAC system permit | 1.48% of construction value (≈ $2,220 on the same value) |
| Occupancy inspection (prior to completion) | $109.79; extra inspections beyond the OBC minimum $109.79 each |
| Residential driveway & parking | Refundable security deposit set annually by the Chief Building Official (forfeited if hard-surfacing isn't completed within one year of occupancy) |
Under the Development Charges Act as amended by Bill 23, a qualifying additional residential unit ancillary to the principal dwelling is EXEMPT from municipal development charges — a major saving versus what a new detached house pays. Confirm the exemption for your specific project with the Town.
How long does an ADU building permit take in Smiths Falls?
Ontario's Building Code requires a decision on a complete house-class application within 10 business days. A detached additional residential unit is OBC Part 9 (house class), so the legislated review window is 10 business days for a complete application. The Town clears applicable law internally, and a lot in an RVCA-regulated area needs that approval first, which can add time.
Worth knowing before you apply
- Submit the Application to Construct or Demolish in person at Town Hall, by email to building@smithsfalls.ca, or online via the Town's Electronic Building Permit Application Portal
- The Town clears 'applicable law' (Planning & Land Use, Public Works & Utilities, Fire, Building) internally on the owner's behalf — so processing time varies with how many areas need to weigh in
- Electrical is a separate permit through the Electrical Safety Authority (1-877-372-7233), not the Town
- A lot near the Rideau River/Canal, a wetland, or a mapped floodplain needs a Rideau Valley Conservation Authority (RVCA) approval before the building permit
- The big saving: a new house pays development charges, but a qualifying ADU is EXEMPT under Bill 23 — make sure the exemption is applied
- Fees are from the 2026 schedule (annually CPI-indexed) and depend on your construction value — confirm current figures with Building Services
Fees and timelines are estimates from Smiths Falls's published schedules, verified July 9, 2026. Rates and processes change — always confirm current requirements with the building department before you apply.
Grants & financing in Smiths Falls
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 →
Smiths Falls modular homes — FAQ
Can you build a garden suite / ADU in Smiths Falls?
Yes — Smiths Falls’ Zoning By-law 10375-2022 (§4.2) permits an additional residential unit as-of-right, and it may be inside the house or in a detached accessory building (a backyard suite). It’s capped at 40% of your home’s gross floor area, needs 1 parking space, and requires a building permit.
How big can a backyard suite be in Smiths Falls?
Up to 40% of your home’s gross floor area — there’s no fixed maximum m² cap. Height and side setbacks follow your zone’s main-dwelling standards, with a minimum 1.2 m rear-yard setback, and the suite counts toward your zone’s lot coverage. Enter your address for the specifics.
Can you build an ADU on well and septic in Smiths Falls?
The by-law permits an additional residential unit where adequate public OR private water and sanitary sewer services are available (§4.2.4), so a private well+septic lot can qualify with a septic-capacity confirmation. Most of Smiths Falls is on full municipal water and sewer, so town lots typically qualify outright.
Can you put a modular home in Smiths Falls, Ontario?
Yes. On land you own, a modular home on a permanent foundation is legal residential housing under the Ontario Building Code throughout the Town of Smiths Falls — as the principal dwelling or as an additional residential unit.
How much does a modular home or backyard suite cost in Smiths Falls?
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 Smiths Falls?
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 Smiths Falls Comprehensive Zoning By-law 10375-2022, §4.2 — Additional Residential Units (Council adopted August 22, 2022); verified by Modular Homes 400 and reviewed by James Clarke, REALTOR®. Always confirm current requirements with the City of Smiths Falls before you build.