Multiplex Conversion in Toronto — Duplex, Triplex, Fourplex As-of-Right

Multiplex Conversion (2-4 Plex) in Toronto GTA

RenoHouse converts existing Toronto detached, semi-detached, and row-house homes into legal 2-, 3-, and 4-unit multiplexes — duplex, triplex, fourplex — under Toronto Bylaw 474-2023 (multiplex as-of-right, May 2023) and the broader Bill 23 / Bill 109 framework. Multiplexes are permitted city-wide in RD, RS, and RT zones, with similar built-form standards to detached houses. We also build new-construction multiplexes from the ground up where the homeowner is rebuilding or where a tear-down strategy makes sense. **What 474-2023 enables.** Up to 4 units (duplex, triplex, fourplex) on every lot in RD, RS, and RT zones. Maximum height up to 10 m where existing zoning permits. Up to two porches/decks/balconies per unit. NO parking minimums (already removed February 2022 city-wide). Front-entrance restrictions for secondary suites have been deleted. Multiplex buildings can be conversions of existing homes OR new construction. The bylaw effectively ended single-family-only zoning in Toronto, three years ahead of any provincial mandate. **Conversion scope.** A typical 4-unit conversion of a 2,000–2,500 sq ft existing detached home includes: structural engineering (new beams for relocated bearing walls, sometimes underpinning of existing foundation for basement unit head height), 45-minute fire separation between units (Type 1 or Type 2 assembly per OBC 9.10.9), independent egress for each unit (typically separate exterior doors), independent HVAC and metering per unit (or sub-metered with landlord-paid utilities), independent kitchens and full bathrooms, smoke and CO interconnection per OBC 9.10.19, sound transmission control (STC ≥ 50 between dwelling units per OBC 9.11), and ESA-permitted electrical with sub-panels for each unit. **Cost (2026 CAD).** Conversion hard cost $200–$400 per square foot of renovated area on top of the existing structure (so a 2,500 sq ft home renovated as 4-plex: $500K–$1M conversion cost). Smaller-scope 2-unit basement legalization or duplex conversion: $100K–$250K. Mid-scope 3-unit (basement + two main-floor units): $250K–$500K. Full 4-unit conversion with structural changes and additions: $500K–$1M. New-build multiplex (tear-down + new construction): $350–$550 per square foot, $700K–$1.5M for a typical 3,000 sq ft 4-unit. **Code requirements (Ontario Building Code Part 9 and Part 11).** Fire separation 45-minute Type 1 between dwelling units (gypsum drywall assembly, fire-rated doors). Sound separation STC ≥ 50 between units. Smoke alarm and carbon monoxide interconnection across all units. Each unit must have independent egress (means of egress per OBC 9.9). Each unit needs full kitchen, full bathroom, independent heating control. Window openings sized for natural light and ventilation per OBC 9.7. Electrical sub-metering per ESA Section 8 (or single-meter with landlord-paid utilities). Plumbing per OBC 7 with separate fixture counts per unit. **Pitfalls we manage.** (1) Underpinning for basement unit head height — required when ceilings are < 6'5" (1.95 m); $30K–$80K added cost depending on perimeter and foundation type. (2) Egress from second/third floor — when interior staircase is shared, fire separation of the staircase becomes the critical OBC issue; sometimes an exterior fire escape is the only practical solution. (3) Heritage Conservation Districts — exterior alteration triggers Heritage Permit; major modifications may not be approvable. (4) Vacant possession — most full-scope conversions require vacant possession during construction; tenant management and Landlord and Tenant Board procedures are the homeowner's responsibility, not ours. (5) Development charges — 3rd and 4th units are Bill 23 exempt ($0); 5th unit and beyond triggers standard DCs (~$45K–$55K per unit) but is generally not in scope under 474-2023. **The 5-unit play (CMHC MLI Select).** Sophisticated investors pursue a 4-unit multiplex (main house) PLUS a garden suite or laneway suite (1 additional unit) = 5 units total, which crosses the CMHC MLI Select threshold. MLI Select unlocks up to 95% LTV financing, up to 50-year amortizations (with surcharge above 25), and forgivable energy-efficiency grants up to $85K/unit for NZE-ready builds. We deliver the construction; the financing structuring is between you and your mortgage broker — we do NOT arrange financing. **Timeline.** Smaller 2-unit conversions: 4–8 months. 3-unit conversions: 6–12 months. Full 4-unit conversions with structural changes and additions: 12–18 months. New-build multiplex tear-downs: 14–24 months including demolition and rebuild. Vacant possession during construction is required for most full-scope conversions. **Honest scope.** RenoHouse handles construction, project management, permits (building, ESA, plumbing, demolition), and trade coordination. Architectural design and structural engineering are delivered through named OAA-licensed and PEng-licensed partners — not in-house. We do not arrange financing, prepare income tax returns, or represent landlords at the Landlord and Tenant Board. Serving Toronto, Mississauga, Brampton, Vaughan, Markham, Richmond Hill, Oakville, Burlington, Etobicoke, Scarborough, North York, and all GTA communities. Call 289-212-2345 for a free conversion-feasibility consultation.