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Serving the Town of Carleton Place (Lanark County)
Modular Homes & Garden Suites in Carleton Place, Ontario
Factory-direct modular homes and backyard suites for the Town of Carleton Place — the Mississippi River town in Lanark County, about 45 minutes west of Ottawa. Carleton Place is unusual and unusually good for a backyard suite: the whole town runs on a Development Permit system rather than a traditional zoning by-law, and its Development Permit By-law 53-2025 puts NO fixed square-footage cap on an additional residential unit. Here's what it allows, what it costs, and the rules that apply.
What you can build in Carleton Place
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 Carleton Place'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 Carleton Place 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? (Carleton Place lots typically allow up to ~700 sq ft)
Carleton Place sets no maximum size for an additional residential unit — §3.4(5) exempts it from the primary dwelling’s maximums. What limits your suite is coverage: all accessory buildings together can cover no more than the lesser of 45% of the rear yard or 15% of the lot. 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 Carleton Place address →Can you put a garden suite (ADU) in your Carleton Place backyard?
Often, yes — Carleton Place permits a detached Additional Residential Unit on most serviced residential lots. The specifics, from Town of Carleton Place Development Permit By-law No. 53-2025, §3.4 — Additional Residential Units (passed June 24, 2025; repeals the previous Development Permit By-laws in their entirety):
| Max size | No fixed cap. §3.4(5) says an additional residential unit is not subject to the size maximums of the main house, and §4.2.3 waives the minimum lot area. Your real limit is coverage — all accessory buildings combined can cover no more than the lesser of 45% of the rear yard or 15% of the lot, and everything counts toward the 60% overall lot coverage. |
|---|---|
| Where it goes | Up to 4 additional units on a lot with a legally existing detached, semi-detached or townhouse dwelling — but only ONE may be a separate building in the yard (the other three must be inside the house). Not permitted in a front or exterior side yard. |
| Height & setbacks | 7 m (≈23 ft) for an accessory structure used for residential purposes — generous enough for two storeys, versus 4.5 m for an ordinary shed or garage. Minimum 1.2 m (≈4 ft) from any interior side lot line, rear lot line, or other structure. |
| Parking | 1 space for the primary dwelling plus 1 space for each additional unit (§3.33(8)); a reduction may be available by paying cash-in-lieu |
| Servicing | Municipal water and sewer are required (§3.47). About 90 lots in town are still not on sanitary sewer; building there is an exceptional path needing a Class 3 Development Permit plus proof that municipal services cannot be extended. |
| Conservation | Mississippi Valley Conservation Authority (MVCA) — a suite is NOT permitted anywhere in the 1:100-year floodplain, and there is a 30 m setback from any watercourse or waterbody. MVCA also issues septic permits here through the Mississippi-Rideau Septic System Office. |
Getting your building permit in Carleton Place
An eligible lot still needs a building permit before anything is delivered. Here's how Carleton Place's process actually works — verified against the Carleton Place building department's own pages.
How do you apply for an ADU building permit in Carleton Place?
Through Citywide Portal — Town of Carleton Place Building Department (application portal ↗). Submit through the Citywide Portal, by email to buildingadmin@carletonplace.ca, or in person at Town Hall (175 Bridge Street). NOTE that Carleton Place runs a Community Planning Permit system, so a DEVELOPMENT PERMIT under By-law 53-2025 is needed in addition to the building permit — there is no zoning certificate or minor variance process. Electrical is a separate permit through the Electrical Safety Authority. Carleton Place's building-permit page ↗
- Confirm your Development Permit Area — an additional residential unit in an accessory building is permitted in the Residential area under Development Permit By-law 53-2025 §3.4; if your property is in the Mississippi Residential or High Street Residential area, confirm with Development Services first (the by-law's wording is ambiguous there)
- Check the Mississippi Valley Conservation Authority floodplain mapping — a suite is NOT permitted anywhere in the 1:100-year floodplain, and there is a 30 m setback from any watercourse or waterbody
- Apply for a Development Permit (Class 1 for a single additional unit; Class 1A where two or more additional units are proposed)
- Retain a qualified BCIN designer for the Ontario Building Code Part 9 drawings plus an SB-12 energy-efficiency compliance sheet
- Submit the building permit application with drawings and fees via the Citywide Portal, email or in person
- Respond to Engineering review comments (§3.4(2) requires an Engineering review for an accessory-building unit) and pay fees
- Book building inspections, plus a separate ESA electrical inspection
What does a Carleton Place ADU permit application need?
- Development Permit application under By-law 53-2025 (Class 1, or Class 1A for two or more additional units)
- Application for a Permit to Construct or Demolish + Designer Information + SB-12 compliance sheet
- Site plan, foundation plan, floor plan, elevations, and section/detail drawings
- Engineering review documentation (§3.4(2))
- MVCA permit where the lot is in a regulated area — within a watercourse or wetland, within 15 m of a floodplain, slope or meander hazard, or within 30 m of a wetland
- Confirmation of municipal water and sanitary connection (§3.47)
How much does an ADU building permit cost in Carleton Place?
Carleton Place is an unusually inexpensive place to permit a backyard suite. The building permit for an additional dwelling unit — in a house OR in a residential accessory structure — is a $500 flat fee rather than a per-square-foot or percentage-of-value charge, plus roughly $350 for a Class 1 Development Permit: on the order of $850 in permit fees. The far bigger number is what you DON'T pay: a new house attracts about $40,585 in development charges (about $39,549 Town + $1,036 Lanark County), and a qualifying additional unit is exempt. Figures from the Fees and Charges By-law 83-2025 (passed November 4, 2025, effective January 1, 2026), Town DC By-law 09-2025 and Lanark County DC By-law 2021-42. Confirm current figures with the Building Department — see the gotchas for two fee questions the schedule does not settle.
| Building permit — additional dwelling unit | $500.00 flat fee for any additional dwelling unit in a house or residential accessory structure (2026 fee schedule); minimum permit fee $130.00 |
|---|---|
| Development Permit | Class 1 about $350 for a single additional unit; Class 1A about $2,500 where two or more additional units are proposed |
| Accessory structure with foundation | $200.00 flat — confirm whether this is charged in addition to the $500 unit fee for a detached suite |
| Second water meter | About $69.37 per quarter once the unit is connected |
| Septic permit (rare) | Issued by the Mississippi Valley Conservation Authority through the Mississippi-Rideau Septic System Office, not a health unit — about $885 for a Class 4/5 residential system (2022 schedule, confirm current) |
A qualifying additional residential unit is EXEMPT from development charges, and the Town has written the exemption into its own DC By-law 09-2025 rather than leaving it to the statute — the clause covers one residential unit in a building or structure ancillary to an existing detached, semi-detached or rowhouse dwelling where that dwelling contains no more than two units. Lanark County's charge falls away automatically with it, because the County by-law exempts anything the lower-tier by-law exempts. That is roughly $40,585 avoided. Two caveats: the Town permits up to four additional units while the exemption reaches the second and third, so a fourth unit may attract the full charge; and the County by-law expires December 8, 2026, so re-check that figure after that date.
How long does an ADU building permit take in Carleton Place?
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 building-permit review window is 10 business days for a complete application. Budget additional time ahead of that for the Development Permit and the Engineering review that §3.4(2) requires, and for an MVCA permit if the lot is in a regulated area.
Worth knowing before you apply
- Carleton Place has no traditional zoning by-law — the whole town is a Community Planning Permit area, so you need a Development Permit rather than a zoning certificate, and there is no minor variance process to fall back on
- A suite is not permitted anywhere in the 1:100-year floodplain as mapped by the Mississippi Valley Conservation Authority, and our automatic zone check cannot see the floodplain — confirm your lot with MVCA directly
- The by-law limits an accessory-building unit to 'the Residential District', a phrase that appears exactly once in the 155-page by-law and is never defined; whether it reaches the Mississippi Residential and High Street Residential areas is genuinely unclear, so confirm with Development Services if you are in one of those
- Municipal water and sewer connection is required; septic systems and wells are a prohibited use except through a Class 3 Development Permit, which needs proof that municipal services cannot be extended for technical reasons
- Two fee questions the schedule does not settle: whether a detached suite pays the $500 unit fee alone or $500 plus the $200 accessory-structure-with-foundation fee, and whether the $1,000 New Housing application review fee (normally credited against the final permit) applies to an ADU-only application
- ⚠️ The Town's published 'Secondary Suites' information sheet is out of date — it still describes the repealed by-law including a 40% size cap that no longer exists. Rely on Development Permit By-law 53-2025
- The Lanark County development charge is frozen at $1,036 but its by-law expires December 8, 2026 with no successor published yet — re-check after that date
- Electrical is a separate permit through the Electrical Safety Authority, not the Town
Fees and timelines are estimates from Carleton Place's published schedules, verified August 11, 2026. Rates and processes change — always confirm current requirements with the building department before you apply.
Grants & financing in Carleton Place
Development charges — exempt for a qualifying additional unit — A new house in Carleton Place pays roughly $40,585 in development charges (about $39,549 to the Town plus $1,036 to Lanark County). The Town’s own DC by-law writes the Bill 23 exemption in for a unit in a building ancillary to an existing house, and the County charge falls away with it — so a qualifying backyard suite avoids that cost entirely. Confirm your project qualifies; the exemption is written for the second and third unit.
Building permit — $500 flat fee — The Town’s fee schedule (By-law 83-2025, effective January 1, 2026) charges a $500 flat fee for any additional dwelling unit in a house or residential accessory structure — a notably low figure by Ontario standards.
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 →
Carleton Place modular homes — FAQ
Can you build a garden suite / ADU in Carleton Place?
Yes. Development Permit By-law 53-2025 (§3.4) permits up to four additional residential units where you have a legally existing detached, semi-detached or townhouse dwelling — three inside the house and one in a separate building in the yard. The detached unit needs a Development Permit, must meet the Ontario Building Code, and cannot be in the 1:100-year floodplain.
How big can a backyard suite be in Carleton Place?
There is no fixed maximum size. §3.4(5) expressly exempts an additional residential unit from the size maximums that apply to the main house, and §4.2.3 waives the minimum lot area. What limits you is coverage — all accessory buildings combined can cover no more than the lesser of 45% of your rear yard or 15% of your lot — plus a 7 m height limit, which is generous enough for a two-storey unit.
Does Carleton Place have a zoning by-law?
No — and this surprises people. The entire town operates under a Community Planning Permit system, so Development Permit By-law 53-2025 replaces the traditional zoning by-law, site plan control and minor variances. You apply for a Development Permit rather than a zoning certificate. A single additional unit is generally a Class 1 permit; two or more trigger a more expensive Class 1A permit.
Do you pay development charges on an ADU in Carleton Place?
Generally no. A new house pays roughly $40,585 in combined Town and Lanark County development charges, but the Town has written the Bill 23 exemption for an ancillary unit into its own by-law, and the County charge falls away with it. The building permit itself is a $500 flat fee. Confirm your specific project qualifies.
Can you build an ADU on well and septic in Carleton Place?
Generally no. §3.47 requires connection to municipal water and sanitary services, and septic systems and wells are a prohibited use except under that section. About 90 lots in town are still not on sanitary sewer, but building there needs a Class 3 Development Permit plus a hydrogeology study and proof that municipal services cannot be extended for technical reasons. Septic permits, where they apply, come from the Mississippi Valley Conservation Authority — not a health unit.
Can you put a modular home in Carleton Place, 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 Carleton Place. The by-law defines a mobile home as one built to CSA Z240, so a CSA A277 modular unit falls outside that definition.
How much does a modular home or backyard suite cost in Carleton Place?
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 Carleton Place?
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 Carleton Place Development Permit By-law No. 53-2025, §3.4 — Additional Residential Units (passed June 24, 2025; repeals the previous Development Permit By-laws in their entirety); verified by Modular Homes 400 and reviewed by James Clarke, REALTOR®. Always confirm current requirements with the City of Carleton Place before you build.