Home/Modular Homes by City/Severn
Serving the Township of Severn & Simcoe County
Modular Homes & Garden Suites in Severn, Ontario
Factory-direct modular homes and backyard suites for the Township of Severn — Coldwater, Washago, Port Severn, Westshore, Fesserton, Marchmont, Ardtrea, and the surrounding communities. New for 2026: Severn's zoning update (By-law 2026-40, in force June 2026) permits a detached additional residential unit as-of-right across the Township, on municipal services or a private well & septic. Here's what the by-law allows, what it costs, and the rules that apply.
What you can build in Severn
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 Severn'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 Severn 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? (Severn lots typically allow up to ~1,000 sq ft)
Severn caps a detached suite at the lesser of 75% of your home’s floor area or 110 m² (≈1,184 sq ft). It’s not permitted on the non-serviced or restricted shoreline zones (SR2/SR3) or in a waterfront front yard, and Coldwater has a mapped Coldwater River floodplain to check — 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 Severn address →Can you put a garden suite (ADU) in your Severn backyard?
Often, yes — Severn permits a detached Additional Residential Unit on most serviced residential lots. The specifics, from Township of Severn Comprehensive Zoning By-law 2010-65 §3.3 Additional Residential Units (added as-of-right by By-law 2026-40, in force June 3, 2026):
| Max size | The lesser of 75% of your home’s floor area or 110 m² (≈1,184 sq ft) |
|---|---|
| Max height | 5.0 m (≈16 ft), one storey — up to 8 m (≈26 ft) with the suite in an upper half-storey/second storey, and never taller than your main house |
| Setbacks | Follow the zone’s principal-building yard setbacks (not the smaller accessory-building ones) · 3.0 m (≈10 ft) separation from any other building with a dwelling · in the rural zones, within 75 m (≈246 ft) of the main house |
| Units per lot | Up to 2 additional units (one in the house + one detached) — 3 units in total with the main house; only one may be detached |
| Parking | 1 space per additional unit (tandem allowed) |
| Where allowed | As-of-right in the R1, R2, RM1, ER, SR1, RR, AG, RU and GL zones — NOT in the SR2/SR3 shoreline zones or a waterfront front yard |
| Servicing | Private well & septic permitted (with an OBC septic-capacity review); on municipal services in Coldwater/Washago, an annual ARU servicing allocation applies |
| Conservation | Lake Simcoe Region CA in southern Severn; much of the Coldwater River corridor is outside any regulated CA (Severn Sound Environmental Association monitors but doesn’t issue permits) |
Getting your building permit in Severn
An eligible lot still needs a building permit before anything is delivered. Here's how Severn's process actually works — verified against the Severn building department's own pages.
How do you apply for an ADU building permit in Severn?
Through Email submission (no online portal — NOT Cloudpermit). Severn does not use Cloudpermit. Email your complete PDF application package (the application form + Schedule 1 designer info + all drawings) to buildingpermits@severn.ca; in-person by pre-scheduled appointment (drawings emailed first) or by mail are the alternatives. Staff don't start reviewing a permit until the application is complete. Severn's building-permit page ↗
- Confirm zoning FIRST with Planning (planning@severn.ca, 705-325-2315 x246) — Severn strongly recommends this before you design or apply; a non-complying lot needs a minor variance or rezoning
- Retain a qualified BCIN designer for the construction drawings (a Schedule 1: Designer Information form is required)
- On a private-septic lot, have a licensed septic designer prepare the septic design + flow calculations and a Schedule 2: Septic Designer form — this is how the added unit's flow is shown to fit the system
- Have an engineered lot grading plan prepared (required for every new dwelling unit)
- Email the complete PDF package to buildingpermits@severn.ca — the Township won't begin review until the application is complete
- Respond to any plan-review deficiencies, then pay all fees (no permit is issued until fees are paid)
- Book inspections at severn.ca/inspections with two business days' notice
What does a Severn ADU permit application need?
- Application for a Permit to Construct or Demolish (one per structure) + Schedule 1: Designer Information
- Site plan showing all structures, setbacks to the lot lines, and the septic system and well
- Floor plans + digital construction drawings, an HVAC plan with heat loss/gain, the engineered truss/floor package, an Energy Efficiency Design Summary (EEDS), and plumbing drawings
- Digital engineered Lot Grading Plan
- Schedule 2: Septic Designer information + septic design drawings + septic flow calculations (on a private well+septic lot)
- Letter of Authorization if the applicant is not the owner
How much does an ADU building permit cost in Severn?
Estimate for a ~700 sq ft detached ADU: roughly $1,190 for the building permit ($180 base + $1.44/sq ft) plus about $723 for a new septic system, $12.50 per plumbing fixture, and a $3,647 refundable lot-grading deposit. Figures from Severn Building By-law 2021-91 Schedule "A" (fees updated January 1, 2026, indexed annually) — confirm current-year figures with the Building Department.
| Base application fee | $180 per permit (Building By-law 2021-91 Sch. "A" §1.1) |
|---|---|
| Building permit — dwelling unit | $1.44 per sq ft, Group C dwelling (Sch. "A" §4.7) — a detached ADU is a dwelling unit, so a ~700 sq ft suite ≈ $1,008 plus the $180 base |
| New septic system | $723 flat for a new Class 3/4 sewage system (Sch. "A" §8.2); a capacity review of an existing system is $108/hr, min 1 hr |
| Plumbing | $12.50 per fixture (Sch. "A" §7.1) |
| Lot grading deposit | $3,647 refundable per lot (Sch. "A" §14.2) |
A qualifying detached ADU (one unit ancillary to the house) is EXEMPT from Township development charges under Severn DC By-law 2024-47 §3.5(d)/(g) (the Bill 23 / More Homes Built Faster framework); County of Simcoe and school-board DCs follow the same provincial ADU exemption. For contrast, a NEW principal single-detached dwelling carries roughly $38,816 in combined DCs (Township + County + school boards, Building Permit Guide Table 1) — the ADU itself avoids that.
How long does an ADU building permit take in Severn?
Ontario's Building Code requires a decision on a complete house-class application within 10 business days. A detached ADU is OBC Part 9 (house class), so the legislated review window is 10 business days for a complete application; Severn advises applying well in advance because summer volumes extend review times. Inspections need two business days' notice.
Worth knowing before you apply
- Severn is email-submission, NOT Cloudpermit — send your complete PDF package to buildingpermits@severn.ca, and note that departments don't review anything until the application is complete
- Talk to Planning before you design: Severn strongly recommends confirming the lot's zoning permits the ADU up front (planning@severn.ca) — a non-complying lot means a minor variance or rezoning first
- Septic capacity is the binding gate on most Severn lots — Severn's OWN Building Department is the Part 8 septic authority (not the health unit), and a licensed septic designer's Schedule 2 + flow calculations are how the added unit is shown to fit
- A qualifying detached ADU is EXEMPT from Township development charges (DC By-law 2024-47 §3.5) — a real saving versus a new principal dwelling
- Budget the $3,647 lot-grading deposit per lot — it's refundable, but you need the cash up front
- Coldwater-area and waterfront lots can face extra review — LSRCA regulates southern Severn and the Coldwater River floodplain may apply; conservation applicability is address-specific, so confirm per-address before you design
- The entrance/driveway permit fee (if a new access is needed) is a separate Public Works charge — on a County road it's billed by the County of Simcoe — and the exact figure isn't published online; confirm it directly
Fees and timelines are estimates from Severn's published schedules, verified July 7, 2026. Rates and processes change — always confirm current requirements with the building department before you apply.
Grants & financing in Severn
County of Simcoe Secondary Suites Program — Simcoe County offers a 15-year forgivable loan (recent materials cite up to $30,000–$50,000/unit — confirm the current cap) to create a secondary or garden suite rented to an income-qualified tenant. Severn is in Simcoe County, so Township properties qualify.
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 →
Severn modular homes — FAQ
Can you put a garden suite in Severn (Coldwater, Port Severn…)?
Yes. Since By-law 2026-40 (June 2026) Severn permits a detached additional residential unit as-of-right across the Township — in the residential, rural and agricultural zones — subject to the size, height, and setback rules and a building permit. It is not permitted on the non-serviced/restricted shoreline zones (SR2/SR3) or in a waterfront front yard.
How big can a garden suite be in Severn?
A detached suite is capped at the lesser of 75% of your home’s floor area or 110 m² (≈1,184 sq ft), one storey and 5.0 m tall (up to 8 m with the suite in an upper storey). Check your address for the specifics — a Coldwater lot may also carry a floodplain overlay.
Can you build an ADU on well and septic in Severn?
Yes. Most of Severn is on private well and septic, and a detached suite is permitted on private services — the added unit’s sewage flow just has to fit your septic system under the Ontario Building Code (Part 8 review).
Can you put a modular home in Severn, Ontario?
Yes. On land you own, a modular home on a permanent foundation is legal residential housing under the Ontario Building Code throughout Severn — the by-law now defines a CSA A277 “Modular Home” distinctly from a mobile home or park-model trailer.
How much does a modular home or backyard suite cost in Severn?
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 Severn?
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 Township of Severn Comprehensive Zoning By-law 2010-65 §3.3 Additional Residential Units (added as-of-right by By-law 2026-40, in force June 3, 2026); verified by Modular Homes 400 and reviewed by James Clarke, REALTOR®. Always confirm current requirements with the City of Severn before you build.