Home/Modular Homes by City/Whitby
Serving Whitby & Durham Region
Modular Homes & Garden Suites in Whitby, Ontario
Factory-direct modular homes and backyard suites for Whitby and Durham Region. Here's what Whitby's additional-dwelling-unit by-law allows in your backyard, what it costs, and the rules that apply.
What you can build in Whitby
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 Whitby'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 Whitby 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? (Whitby lots typically allow up to ~750 sq ft)
Whitby allows a detached suite up to 75 m² (≈807 sq ft). Your exact lot may allow more or less — get the real number for your address in seconds.
Check your exact Whitby address →Can you put a garden suite (ADU) in your Whitby backyard?
Often, yes — Whitby permits a detached Additional Residential Unit on most serviced residential lots. The specifics, from Town of Whitby Zoning By-laws 1784 / 2585 / 5581-05 (ADU provisions):
| Max size | 75 m² (≈807 sq ft) for a detached suite |
|---|---|
| Max height | 4.5 m (≈15 ft) in residential zones; 5.5 m (≈18 ft) in other zones |
| Setbacks | 1.2 m (≈4 ft) rear and side |
| Units per lot | Up to 3 additional units — at most one detached |
| Parking | 1 space per ADU (tandem or a reduced 2.5 m × 5.0 m space allowed; none required in a Major Transit Station Area) |
| Servicing | Municipal water & sewer, or Durham Health-confirmed private servicing |
| Conservation | Central Lake Ontario (CLOCA); TRCA in the west |
Getting your building permit in Whitby
An eligible lot still needs a building permit before anything is delivered. Here's how Whitby's process actually works — verified against the Whitby building department's own pages.
How do you apply for an ADU building permit in Whitby?
Through Town of Whitby E-Portal (application portal ↗). Apply through the Town's E-Portal (preferred), by email, or on paper in person — E-Portal submissions must follow the Town's file-naming convention and submission standards. Whitby's building-permit page ↗
- Start with a pre-application consultation with Building Services (building@whitby.ca) to confirm zoning compliance for the detached unit
- Determine what other approvals apply — minor variance, CLOCA permit, or Durham Region Health Department approval on septic lots
- Prepare the mandatory documents: the provincial Application to Construct or Demolish, Schedule 1 Designer Information, drawings per the Town's ADU Design Guide, and the Applicable Law Checklist
- Submit through the E-Portal following the file-naming and submission-standards guides
- The Town pre-screens for completeness, then issues an invoice — pay it and formal plan review begins
- Once the permit issues, schedule inspections during construction, plus a final exterior inspection before occupancy
- Register the ADU with By-Law Services (required under Registration By-law 8156-25)
What does a Whitby ADU permit application need?
- Application to Construct or Demolish (the provincial form)
- Schedule 1: Designer Information form(s)
- Drawings meeting the Town's Additional Dwelling Unit Building-Specific Design Guide and the Building Code
- Applicable Law Checklist + Letter of Authorization if applying on the owner's behalf
- CLOCA permit where the lot is in a regulated area; Durham Region Health approval on private septic
- Certificate of Acceptance from a Licensed Electrical Contractor (during construction)
How much does an ADU building permit cost in Whitby?
Expect roughly $600 in Town permit fees for a typical ~600 sq ft (55 m²) detached ADU at the 2026 accessory-structure rate of $10.65 per m² (minimum fee $305) — an estimate; ask staff which fee code applies to a new-build detached ADU before quoting an exact figure. The bigger number: Whitby's ADU Incentive Agreement can reimburse the permit fee, registration inspection fee, curb-cut fee, and (for detached ADUs) Education Development Charges.
| Permit fee | $10.65 per m² for new residential accessory structures (2026 Schedule N, By-law 7220-17); minimum $305 |
|---|---|
| ADU registration | $268 (rises to $534 if the Town discovers an unregistered ADU via a complaint; $107 to transfer to a new owner) |
| ADU Incentive Agreement | Reimburses the permit fee, registration inspection fee, curb-cut fee, and Education Development Charges for detached ADUs — hard deadlines apply (see below) |
Whitby's DC by-law exempts ADUs that add no new floor area to an existing building; a new detached ADU isn't automatically exempt — but Education Development Charges on detached ADUs are reimbursable under the ADU Incentive Agreement.
How long does an ADU building permit take in Whitby?
Ontario's Building Code requires a decision on a complete house-class application within 10 business days. The Town recommends submitting at least two weeks before any incentive-program deadline to allow processing time.
Registration: All ADUs must be registered with By-Law Services under Registration By-law 8156-25 — $268, rising to $534 if an unregistered unit is discovered via a complaint.
Worth knowing before you apply
- The ADU Incentive Agreement has hard deadlines: the permit application must be complete by December 31, 2026, the signed agreement returned by March 31, 2027, and the ADU registered by March 31, 2027 — miss the registration date and the incentive must be repaid
- Whitby and Pickering jointly publish an ADU Regional Design Catalogue of five pre-approved detached designs (permit review then covers siting only) — round-1 submissions are closed and a second round was anticipated via HAF-ADU@whitby.ca; confirm current status
- A private-septic lot needs Durham Region Health Department approval before or alongside the permit — the common trip-up on Whitby's rural/estate lots
- Lots near a watercourse, wetland, or floodplain need a separate CLOCA permit on top of the building permit
- Breaking ground before the permit issues triggers a penalty fee under the 2026 fee schedule
Fees and timelines are estimates from Whitby's published schedules, verified July 4, 2026. Rates and processes change — always confirm current requirements with the building department before you apply.
Grants & financing in Whitby
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 →
Whitby modular homes — FAQ
Can you put a backyard suite in Whitby?
Yes. Whitby permits up to three additional dwelling units per lot (with at most one detached) on urban residential land — subject to size, height, and setback rules and a building permit.
How big can a backyard suite be in Whitby?
A detached suite can be up to 75 m² (≈807 sq ft). Check your address for the specifics.
Can you put a modular home in Whitby?
Yes. On land you own, a modular home on a permanent foundation is legal residential housing under the Ontario Building Code throughout Whitby, subject to standard zoning and permits.
How much does a modular home or backyard suite cost in Whitby?
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 Whitby?
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 Whitby Zoning By-laws 1784 / 2585 / 5581-05 (ADU provisions); verified by Modular Homes 400 and reviewed by James Clarke, REALTOR®. Always confirm current requirements with the City of Whitby before you build.