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# Duplex vs Triplex vs Fourplex Toronto: Which Conversion Fits Your Lot (2026)
Bylaw 474-2023 permits up to four units as-of-right on virtually every residential lot in Toronto, but that does not mean every property is a fourplex candidate. The decision between a duplex, triplex, or fourplex conversion depends on existing house size, basement ceiling height, lot frontage, neighbourhood rent ceiling, financing strategy, and the investor's appetite for project complexity. This guide gives you a clear decision framework so you arrive at the right unit count before you buy a property or commit to drawings.
For the regulatory backdrop, see [Multiplex Conversion Toronto: Complete 2026 Guide](/blog/multiplex-conversion-toronto-2026-complete-guide). For the cost detail behind each option, see [Multiplex Conversion Cost Toronto: Full 2026 Breakdown](/blog/multiplex-conversion-cost-toronto-breakdown-2026).
Quick Comparison Table
| Factor | Duplex (2 Units) | Triplex (3 Units) | Fourplex (4 Units) |
|---|---|---|---|
| Conversion cost (typical) | $150K-$280K | $250K-$420K | $400K-$700K |
| Minimum existing house size | ~1,400 sq ft | ~1,800 sq ft | ~2,200 sq ft |
| Minimum lot frontage | 18-22 ft | 22-28 ft | 28-40 ft |
| Basement underpinning required? | Rarely | Sometimes | Often |
| Number of kitchens | 2 | 3 | 4 |
| Number of bathrooms | 2-3 | 3-4 | 4-5 |
| Service upgrade required (200A+) | Sometimes | Usually | Almost always |
| Typical gross monthly rent (Toronto avg) | $4,500-$6,500 | $6,500-$9,500 | $8,500-$13,500 |
| Property tax delta | $1,500-$3,000/yr | $2,500-$4,500/yr | $3,500-$6,500/yr |
| Project timeline | 4-7 months | 6-9 months | 9-14 months |
| Permit complexity | Simple | Moderate | High |
| MLI Select eligible (with garden/laneway suite)? | No (would be 3 units max) | Yes (with ADU = 4) | Yes alone, plus ADU = 5+ |
| Typical investor return (cash-on-cash) | 7-11% | 9-14% | 12-18% |
| Vacancy risk during construction | Low | Moderate | High |
Duplex Conversion: When It Makes Sense
A duplex is two self-contained units on one lot, most commonly an upper-floor unit and a basement (or lower-floor) unit. Toronto homeowners convert to duplex when:
- The lot is small (<22 ft frontage) — narrow Victorian and Edwardian semis in Roncesvalles, Parkdale, Trinity-Bellwoods often max out at duplex without a major rear addition.
- The existing house is under 1,800 sq ft — there is not enough floor area to carve out three or four functional units.
- Heritage Conservation District restrictions limit exterior alterations — adding new entries, balconies, or windows for additional units may not be permitted; a duplex with two existing entries is often the only feasible scope.
- The owner plans to occupy one unit — owner-occupied duplexes (live in upper, rent basement) qualify for the Multigenerational Home Renovation Tax Credit if the basement unit is for a senior or disabled relative (15% refundable credit on up to $50K = max $7,500).
- Cash flow rather than scale is the goal — a duplex generates $4,500-$6,500/mo in combined rent, often enough to cover the entire mortgage on a $1.0M-$1.3M property.
Duplex Cost Profile
Typical Toronto duplex conversion costs $150K-$280K excluding acquisition. The breakdown:
- Soft costs: $25K-$45K.
- Basement legalization (if needed): $50K-$110K including underpinning.
- New stair / separate entry to basement: $15K-$30K.
- Two kitchens: $25K-$45K.
- Two bathrooms (or upgrades to existing): $15K-$30K.
- Mechanical separation: $15K-$30K.
- Fire separation between floors: $10K-$20K.
- Flooring, paint, finishes: $20K-$45K.
- Permits, contingency: $30K-$70K.
Duplex ROI
For a typical $1.1M Old East York semi converted for $220K:
| Metric | Value |
|---|---|
| Acquisition | $1,100,000 |
| Conversion | $220,000 |
| Total all-in | $1,320,000 |
| Gross rent (upper $3,200 + basement $2,000) | $62,400/yr |
| NOI (self-managed) | ~$48,000/yr |
| Cap rate | 3.6% |
| As-improved value | $1,400,000 |
| Property uplift | ~$80,000-$120,000 |
Duplex returns are modest. The play is cash flow stability and ease of management, not maximum capital appreciation.
Triplex Conversion: The Sweet Spot for Most Toronto Bungalows
A triplex is three self-contained units, typically a basement + main floor + second floor (or attic) configuration in a 1,800-2,400 sq ft existing house. The sweet spot conditions:
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- Lot frontage 22-28 ft — wide enough for separate side entry to basement, narrow enough that a fourplex's footprint expansion is impractical.
- Basement ceiling 7'-3" to 8'-0" — shallow underpinning may be needed but not deep.
- Investor wants strong cash flow without project complexity of a fourplex.
- Property is in a mid-tier rent neighbourhood ($2,500-$3,200/mo for 2BR) where four units would price out the local market.
Triplex Cost Profile
$250K-$420K excluding acquisition. Add to the duplex baseline:
- Third kitchen: $14K-$25K.
- Third bathroom: $10K-$18K.
- Additional fire separation between three units: $15K-$25K.
- More extensive HVAC zoning: $8K-$15K.
- 200A service upgrade (more often required): $5K-$12K.
- Possibly a third dedicated entry: $5K-$15K.
Triplex ROI
For a $1.2M Pape Village 2-storey detached converted for $360K:
| Metric | Value |
|---|---|
| Acquisition | $1,200,000 |
| Conversion | $360,000 |
| Total all-in | $1,560,000 |
| Gross rent (upper $2,800 + main $2,800 + basement $2,100) | $92,400/yr |
| NOI (self-managed) | ~$70,000/yr |
| Cap rate | 4.5% |
| As-improved value | $1,650,000-$1,800,000 |
| Property uplift | ~$90,000-$240,000 |
| Cash-on-cash @ 80% LTV refi | 9-14% |
Triplex returns are markedly better than duplex and the project complexity is meaningfully less than a fourplex. This is why the triplex is the dominant conversion type in 2026 Toronto.
Fourplex Conversion: Maximum Returns, Maximum Complexity
A fourplex is four self-contained units, almost always requiring (a) a 2,400+ sq ft existing house, (b) a finished attic + finished basement, AND (c) some form of structural intervention (underpinning, addition, or both). When it makes sense:
- Existing detached home is 2,400-3,200 sq ft with a layout that supports vertical stacking (basement, main, second, attic/third).
- Lot frontage 28-40 ft — wide enough to support multiple separate entries and the fire egress paths required by OBC.
- Investor is targeting BRRRR or CMHC MLI Select — the four-unit base, when combined with a garden or laneway suite, hits the 5-unit MLI Select threshold and unlocks 95% LTV financing.
- Neighbourhood supports 4-unit density without significant pushback — Scarborough, Etobicoke, North York mid-suburbs typically have lots and streetscapes that absorb a fourplex without controversy.
- Project budget allows $400K-$700K of renovation capital plus 10-15% contingency.
Fourplex Cost Profile
$400K-$700K excluding acquisition. The cost step-up from triplex comes from:
- Fourth kitchen: $14K-$25K.
- Fourth bathroom (often a fifth half-bath): $12K-$22K.
- More extensive fire separation (more demising assemblies): $10K-$25K.
- Almost-always 400A or 200A service upgrade: $8K-$15K.
- Often an attic conversion (dormer additions, structural work, third-storey egress): $40K-$120K.
- Often basement underpinning to legalize basement unit: $50K-$120K.
- More extensive mechanical (4 zones): $10K-$25K.
Fourplex ROI
For a $1.275M Birch Cliff bungalow converted for $550K:
| Metric | Value |
|---|---|
| Acquisition | $1,275,000 |
| Conversion | $550,000 |
| Total all-in | $1,825,000 |
| Gross rent (4 × $2,500/mo) | $120,000/yr |
| NOI (self-managed) | ~$92,000/yr |
| Cap rate | 5.0% |
| As-improved value | $2,000,000+ |
| Property uplift | ~$175,000+ |
| Cash-on-cash @ 95% MLI Select financing | 12-18% |
Fourplex returns are the highest of the three options, and crossing into MLI Select with a 5th unit ADU adds another lever. See [Multiplex Conversion Rental Income & ROI Toronto](/blog/multiplex-conversion-rental-income-toronto-roi) for the full ROI mechanics.
The Decision Framework: A Step-by-Step Walkthrough
Use this decision tree on any Toronto property you are evaluating:
Step 1 — Confirm zoning eligibility.Is the lot in RD, RS, or RT? (Almost certainly yes for any single-family-zoned residential lot in Toronto under 569-2013.) If yes, up to 4 units are as-of-right under 474-2023.
Step 2 — Measure existing GFA.- Under 1,800 sq ft above grade → Duplex only.
- 1,800-2,200 sq ft above grade → Triplex realistic, fourplex requires addition.
- 2,200+ sq ft above grade → Fourplex feasible without addition.
- Under 6'-6" clear ceiling height → Underpinning required to legalize basement unit ($50K-$120K).
- 6'-6" to 7'-0" → Bench-footing alternative ($35K-$70K, reduces basement floor area).
- 7'-0" to 7'-9" → Marginal; OBC requires 1.95 m (6'5") under beams, 2.05 m (6'9") in living areas. Borderline cases need engineer review.
- 7'-9" or greater → Compliant as-is; no underpinning needed.
- Under 22 ft → Duplex realistic; triplex challenging due to fire egress paths.
- 22-28 ft → Triplex sweet spot; fourplex possible with strong design.
- 28+ ft → Full flexibility; fourplex typically optimal.
- HELOC + standard refi to 80% LTV → Duplex or triplex; the 80% LTV ceiling supports modest leverage.
- CMHC MLI Select 95% LTV → Need 5+ units. Fourplex + garden/laneway suite is the canonical play.
- All-cash or low-leverage → Any tier; pick the one that fits the property.
- Toronto inner core (Trinity-Bellwoods, Riverdale, Leslieville) → 2BR at $3,200-$3,800/mo. Triplex or duplex can clear strong cash flow.
- Mid-suburb (Birch Cliff, Pape Village, Mimico) → 2BR at $2,400-$2,900/mo. Fourplex needs all 4 units rented to clear strong returns.
- Far-out suburb (Wexford, West Hill, Newtonbrook) → 2BR at $2,000-$2,500/mo. Triplex often better economics than fourplex.
A duplex is well within the capacity of any qualified Toronto general contractor. Triplex requires GC experience with multi-unit fire separation. Fourplex (especially with underpinning, addition, or MLI Select compliance) requires a GC with at least 3-5 prior multiplex projects and an in-house or trusted structural engineer. RenoHouse handles all three tiers.
Common Decision Pitfalls
- 1. "I want to maximize units." Adding a fourth unit is not always the right call. If the marginal fourth unit forces $150K of additional structural work for $1,500/mo of rent, the marginal ROI is poor compared to a clean triplex.
- 2. "I will live in one unit, so I can save." Owner-occupied conversions inherit different financing constraints (insured high-ratio mortgage to 95% on a primary residence is possible) but also forfeit some rental income offset. Run the math both ways.
- 3. "The basement is fine." A 6'-3" basement ceiling is NOT fine for a legal apartment. Confirm headroom before pricing the basement unit's rent into your underwriting.
- 4. "Bylaw 474-2023 means I do not need a permit." As-of-right means no minor variance, NOT no building permit. Building Permit, ESA, plumbing, and HVAC permits are still required.
- 5. "Vacant possession is easy." Existing tenants protected by the Residential Tenancies Act (RTA) cannot be evicted simply because you want to renovate. N13 (own use) and N12 (purchaser own use) notices have specific rules; some properties cannot legally have vacant possession.
Cross-Niche Stacking: Multiplex + Garden Suite
The most aggressive 2026 strategy is to layer a garden or laneway suite onto the multiplex. A fourplex (4 units) + garden suite (1 unit) = 5 units, which is the CMHC MLI Select threshold. This unlocks 95% LTV, 50-year amortization, and forgivable energy grants up to $85K per unit. The combined construction cost runs $700K-$1.5M, but the financing leverage and returns are unmatched. Full breakdown in [Multiplex Financing Toronto: CMHC MLI Select](/blog/multiplex-financing-cmhc-mli-select-toronto). For the garden suite half, see [Garden Suite Toronto: Complete 2026 Guide](/blog/garden-suite-toronto-2026-complete-guide).
Get a Free Lot Assessment
The right unit count is property-specific. RenoHouse offers a free 7-day lot assessment for any Toronto property: zoning verification, existing GFA measurement, basement underpinning review, structural feasibility, and a duplex/triplex/fourplex recommendation with budget estimates for each. [Book your assessment](/services/multi-unit-aru-conversions/multiplex-conversion).
Related Reading
- Pillar: [Multiplex Conversion Toronto: Complete 2026 Guide](/blog/multiplex-conversion-toronto-2026-complete-guide).
- Cost: [Multiplex Conversion Cost Toronto: Full 2026 Breakdown](/blog/multiplex-conversion-cost-toronto-breakdown-2026).
- Basement: [Basement Apartment Legalization Toronto](/blog/basement-apartment-legalization-toronto).
- Permits: [Multiplex Conversion Permits Toronto](/blog/multiplex-conversion-permits-toronto-timeline).
- ROI: [Multiplex Conversion Rental Income & ROI Toronto](/blog/multiplex-conversion-rental-income-toronto-roi).
- Cross-niche: [Garden Suite Toronto](/blog/garden-suite-toronto-2026-complete-guide), [Laneway House Toronto](/blog/laneway-house-construction-toronto-2026-complete-guide).
