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Serving the Town of The Blue Mountains (Grey County)
Modular Homes & Garden Suites in The Blue Mountains, Ontario
Factory-direct modular homes and backyard suites for the Town of The Blue Mountains — Thornbury, Clarksburg, Craigleith, Lora Bay and the escarpment countryside. The Town's 2024 update is generous where it counts: a backyard unit may be up to the GREATER of 50% of your home's floor area or 100 m² (≈1,076 sq ft) — bigger homes unlock more. And the resort-area rule that matters: an additional residential unit legally CANNOT be a short-term rental — long-term tenants only, which is precisely what makes it a sound long-term rental investment in a town short on year-round housing. Here's what By-law 2018-65 allows, what it costs, and the rules that apply.
What you can build in The Blue Mountains
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 Blue Mountains'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 Blue Mountains 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? (The Blue Mountains lots typically allow up to 1,076 sq ft)
The Blue Mountains' cap works in your favour: the GREATER of 50% of your home's floor area or 100 m² (≈1,076 sq ft) — 100 m² is the floor every host lot gets, and a larger house unlocks more, with a two-bedroom limit. 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 Blue Mountains address →Can you put a garden suite (ADU) in your Blue Mountains backyard?
Often, yes — The Blue Mountains permits a detached Additional Residential Unit on most serviced residential lots. The specifics, from Town of The Blue Mountains Comprehensive Zoning By-law 2018-65, §4.1 as amended by By-law 2024-31 — Additional Residential Units (passed April 15, 2024):
| Max size | The GREATER of 50% of your home's floor area or 100 m² (≈1,076 sq ft) — the opposite of the usual "lesser of" formula, so 100 m² is the floor every host lot gets and a larger house unlocks more — with a maximum of two bedrooms (§4.1.2). |
|---|---|
| How many units | Two additional units on lots with full municipal water and sewer (the Thornbury, Clarksburg, Craigleith, Camperdown, Lora Bay and Swiss Meadows serviced areas); on well-and-septic lots, one unit under 0.8 ha (≈2 acres) and two at 0.8 ha and up (§4.1.1). |
| The detached building | Rear yard 1.2 m (≈4 ft), other yards per the main building, height 5 m (≈16 ft) — or 8 m (≈26 ft) if the suite sits above a garage or other accessory use — within 50 m (≈164 ft) of the house, and the lot’s coverage cap grows by 5 percentage points per unit (§4.1.3). |
| No short-term rental — by law | The by-law’s definition itself excludes short-term accommodation: an additional residential unit houses long-term tenants (30+ days) only. Anyone selling you an “Airbnb suite” in The Blue Mountains is selling something the by-law forbids. The honest upside is the long-term market — a town short on year-round housing. |
| Where it’s allowed | As-of-right in the R1, R2, Agricultural, Special Agricultural and Rural zones. The R3 apartment zone doesn’t carry the right (that reads “not as-of-right”, not no), and Resort Residential (RR) is resort-commercial product — no backyard units there. |
| Escarpment layering | On Niagara Escarpment Plan lots: one unit only, inside the main house, smaller than the house (§4.1.1 c). On NEC Development Control parcels the by-law doesn’t apply at all — that’s Niagara Escarpment Commission Development Permit territory. The Town’s own mapping distinguishes both, and we check it. |
| Parking & servicing | One space per unit. Conservation approvals come from Grey Sauble CA over most of the Town or Nottawasaga Valley CA at the eastern edge — both regulated extents are on the Town’s own GIS. |
Getting your building permit in The Blue Mountains
An eligible lot still needs a building permit before anything is delivered. Here's how Blue Mountains's process actually works — verified against the Blue Mountains building department's own pages.
How do you apply for an ADU building permit in The Blue Mountains?
Through Cloudpermit (Town of The Blue Mountains Building Services) (application portal ↗). The Blue Mountains runs its own Building Services Division and publishes its own Additional Residential Units guide. Applications go through Cloudpermit; accessory-building applications may also go by email to build@thebluemountains.ca or via the Town's secure file transfer (32 Mill Street, Thornbury; 519-599-3131 ext. 290). Blue Mountains's building-permit page ↗
- Confirm the zoning and the count — up to the greater of 50% of your home's floor area or 100 m², two bedrooms; two units on full municipal services, one on a private-serviced lot under 0.8 ha (two at 0.8 ha and up), and on Niagara Escarpment Plan lots one unit inside the main house only.
- Talk to Building Services BEFORE you apply — the Town's own guidance routes applications through the applicable-law check (Niagara Escarpment Commission, conservation authority, MTO) at intake, and which of the two conservation authorities applies (Grey Sauble or Nottawasaga Valley) is address-specific.
- On a rural lot, plan the septic — a new or replacement sewage system permit is $736 (Building By-law 2025-40, Schedule G), and the Town's fee schedule prices the septic work alongside the building permit; confirm the current septic intake process with Building Services.
- Retain a qualified BCIN designer — zoning-compliant scaled drawings; truss and engineered-floor layouts must be stamped by the BCIN holder, engineer or architect.
- Apply through Cloudpermit and pay the FULL permit fee at application (the rule for new dwelling units) — $18.15/m² for a site-built detached dwelling unit, or $13.08/m² for a PREFABRICATED detached dwelling, with no separate plumbing fee when the plumbing goes in with the new building.
- Review, issuance, inspections — the Town cites the legislated 10-business-day house-class window for a complete application.
What does a Blue Mountains ADU permit application need?
- Building Permit Application (via Cloudpermit) — full permit fee due at application for a new dwelling unit
- Zoning-compliant drawings to scale — the Town's ARU guide accepts homeowner-prepared Code-compliant drawings but recommends a design professional
- Truss layout and engineered flooring layout, stamped by the BCIN holder, Professional Engineer or Architect
- Proof of the existing dwelling where the ARU right depends on it (the guide notes age/GFA documentation)
- Septic permit application on a private-serviced lot
- NEC Development Permit or conservation-authority approval where the lot is in the Development Control area or a regulated area
How much does an ADU building permit cost in The Blue Mountains?
Fees follow Building By-law 2025-40 (effective September 1, 2025): a new site-built detached dwelling unit prices at $18.15/m² — but a PREFABRICATED detached dwelling has its own lower rate of $13.08/m², so a 56 m² (≈600 sq ft) modular unit runs roughly $730 versus about $1,020 site-built, with the full fee due at application, a $150 minimum on all work, and no separate plumbing fee when the plumbing is installed with the new building. A new septic system adds $736 on a rural lot. All figures are estimates — confirm with Building Services (519-599-3131 ext. 290).
| Building permit — new detached dwelling unit | $18.15/m² site-built; $13.08/m² for a prefabricated detached dwelling — the Town's own fee schedule prices factory-built lower (Building By-law 2025-40, Schedule A, Group C); minimum fee $150; full permit fee due at time of application |
|---|---|
| Plumbing | No additional fee for plumbing installed at the same time as the new building's construction; standalone residential sanitary or water service work is $150 (By-law 2025-40, Schedule A) |
| Septic (sewage-system) permit | New or replacement sewage system $736; alteration/assessment for building expansion $350 (By-law 2025-40, Schedule A, Section G). The Town's sewer page also points septic questions at Grey Bruce Public Health — confirm the intake desk with Building Services |
| Entrance permit | Issued by the Town's Building Division; the 2021 Fees and Charges By-law set $290 for new entrance works — confirm the current rate, as a newer fees by-law exists |
| Development charges | EXEMPT — the Town's own ARU FAQ says it plainly: 'Currently, ARU's are exempt from Town and County Development Charges', and Town DC By-law 2024-29 (§18) writes the statutory exemption in. Against the five-figure charges a new single-detached home pays in the serviced areas, the exemption is decisive |
The Town's own ARU FAQ (June 2024) answers the question directly: 'Are ARU's exempt from Development Charges? A: Yes! Currently, ARU's are exempt from Town and County Development Charges.' Town DC By-law 2024-29 (§18) defers to the Development Charges Act's statutory ADU exemption — confirm treatment at permit issuance as the FAQ's 'currently' implies.
How long does an ADU building permit take in The Blue Mountains?
Ontario's Building Code requires a decision on a complete house-class application within 10 business days. The Town cites the legislated 10-business-day window for house-class permits on a complete application. The real schedule is set by the pre-steps: the NEC Development Permit where the lot is in the Development Control area, the conservation-authority approval on regulated lands, and the septic design on rural lots — the Town's own advice is to speak with Building Services before applying.
Worth knowing before you apply
- The fee schedule rewards factory-built: a prefabricated detached dwelling prices at $13.08/m² against $18.15/m² site-built — about 28% less permit fee for a modular unit, in the Town's own by-law.
- The ARU legally cannot be a short-term rental — the by-law's definition excludes short-term accommodation, and the Town's FAQ confirms long-term (30+ day) tenancy only. Plan the investment case on the year-round rental market, not resort nights.
- Which conservation authority applies is address-specific — Grey Sauble on the Thornbury/Clarksburg side, Nottawasaga Valley toward the eastern edge — and NEC Development Control parcels route through the Commission before the Town.
- The full permit fee is due at application for a new dwelling unit — not a deposit, the whole fee.
- On Niagara Escarpment Plan lots the right narrows to one unit, inside the main house, smaller than the house — the backyard building isn't available there.
Fees and timelines are estimates from Blue Mountains's published schedules, verified August 28, 2026. Rates and processes change — always confirm current requirements with the building department before you apply.
Grants & financing in The Blue Mountains
Development charges — exempt for a qualifying ADU — Ontario's Development Charges Act (s.2(3)) exempts qualifying additional residential units — up to two units added to an existing home, or one unit in an ancillary building. Grey County's charge ($2,617 single-detached, 2022 schedule, indexed) carries exemption wording written before Bill 23 that speaks to units 'in or attached to' the house — confirm the County's and the Town's treatment of a detached unit when the permit is issued.
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 →
The Blue Mountains modular homes — FAQ
Can you build a garden suite / ADU in The Blue Mountains?
Yes — since April 2024, By-law 2024-31 permits additional residential units as-of-right in the R1, R2, Agricultural, Special Agricultural and Rural zones: up to the greater of 50% of your home’s floor area or 100 m² (≈1,076 sq ft), two bedrooms, and one unit may be a detached backyard building. Two on full municipal services; on well-and-septic lots, one under 0.8 ha and two at 0.8 ha and up. Garden suites proper remain a separate temporary-use instrument.
How big can a backyard suite be in The Blue Mountains?
The GREATER of 50% of your home’s floor area or 100 m² (≈1,076 sq ft) — so 100 m² is the floor every host lot gets and a bigger house unlocks more — with a two-bedroom maximum. The detached building runs to 5 m (≈16 ft) tall (8 m above a garage), sits within 50 m of the house, and earns the lot 5 extra coverage points per unit. Enter your address for the exact number.
Can I rent out an ADU in The Blue Mountains on Airbnb?
No — and this is the rule that matters in a resort town. The by-law’s definition of an additional residential unit expressly excludes short-term accommodation: long-term tenants (30+ days) only. What the rule protects is exactly what makes the unit valuable — The Blue Mountains is chronically short of year-round housing, and a legal long-term rental in that market is a sound investment on its own terms.
Does the Niagara Escarpment affect building in The Blue Mountains?
Yes, in layers. On Niagara Escarpment Plan lots the by-law allows one additional unit only, inside the main house and smaller than it (§4.1.1 c). On NEC Development Control parcels the zoning by-law doesn’t apply at all — a unit there is a Niagara Escarpment Commission Development Permit question. The Town’s own mapping distinguishes both regimes; check your lot before you design, and we can help.
Can you put a modular home in The Blue Mountains, Ontario?
Yes. On land you own, a CSA A277 modular home on a permanent foundation is legal residential housing under the Ontario Building Code throughout The Blue Mountains — as the principal dwelling, or as the detached additional unit in your backyard under §4.1. The by-law requires a permanent year-round dwelling — a recreational trailer or vehicle can never qualify — and a factory-built modular unit on a permanent foundation is exactly that.
How much does a modular home or backyard suite cost in The Blue Mountains?
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 The Blue Mountains?
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 The Blue Mountains Comprehensive Zoning By-law 2018-65, §4.1 as amended by By-law 2024-31 — Additional Residential Units (passed April 15, 2024); verified by Modular Homes 400 and reviewed by James Clarke, REALTOR®. Always confirm current requirements with the municipality before you build.