Multiplex Conversion Cost Toronto: Full 2026 Breakdown ($200-$500K)

# Multiplex Conversion Cost Toronto: Full 2026 Breakdown ($200-$500K)

A Toronto multiplex conversion in 2026 typically costs $200,000 to $500,000+ on top of the acquisition price, with the wide range driven by basement legalization scope, kitchen and bathroom count, the degree of utility separation between units, and whether the existing structure needs underpinning, structural reframing, or fire-rated assembly retrofits. This guide breaks down every line item in current Toronto trade pricing so you can build a realistic budget before signing a Purchase & Sale or pulling building permits.

For the full regulatory and ROI context, see the pillar guide [Multiplex Conversion Toronto: Complete 2026 Guide](/blog/multiplex-conversion-toronto-2026-complete-guide). For the duplex-versus-triplex-versus-fourplex decision before you spend dollars, see [Duplex vs Triplex vs Fourplex Toronto: Which Conversion Fits Your Lot](/blog/duplex-vs-triplex-vs-fourplex-toronto-decision).

The Headline Numbers

Across hundreds of Toronto conversion budgets we have reviewed in 2026, the realistic ranges are:

Conversion Type	Typical Cost (Renovation Only, Excluding Acquisition)
Duplex (2 units)	$150,000-$280,000
Triplex (3 units)	$250,000-$420,000
Fourplex (4 units)	$400,000-$700,000
Fourplex with major addition	$700,000-$1,200,000
Fourplex with full underpinning + addition	$1,000,000-$1,500,000+

These figures are renovation-only costs for an existing detached or semi-detached home in the 1,800-2,800 sq ft range. They exclude purchase price, land transfer tax, and post-construction operating expenses, but include all soft costs, hard costs, permits, finishes, and a typical 10-15% contingency.

Soft Costs vs Hard Costs: The 80/20 Rule

In a typical Toronto fourplex conversion budget, soft costs run 12-18% of the total, with hard construction costs absorbing the remaining 82-88%. The split:

Soft Costs (~12-18% of project)

Item	Cost Range
Architectural design & permit drawings	$15,000-$45,000
Structural engineering (joist sizing, beam design, underpinning if needed)	$5,000-$15,000
Mechanical engineering (HVAC, plumbing schematic, ventilation)	$4,000-$10,000
Electrical engineering / load calculation	$2,000-$5,000
Energy compliance (SB-12 modelling)	$1,500-$3,500
Topographic survey (current OLS)	$1,500-$3,000
Building permit fees	$5,000-$15,000
ESA permit + inspection fees	$1,500-$3,500
Plumbing trade permit	$800-$2,500
HVAC permit	$500-$1,500
Heritage permit (if applicable)	$1,500-$5,000
Builder's risk / Course of Construction insurance	$4,000-$25,000
Project management (if outsourced separately)	$15,000-$50,000
Soft cost total	$57K-$184K

Hard Costs (~82-88% of project)

The bulk of the budget. We break this down by phase below.

Hard Cost Phase Breakdown (Typical Fourplex Conversion)

Demolition & Site Prep ($20,000-$50,000)

Selective interior demolition of partition walls, removal of existing flooring and finishes, removal of one or more interior staircases (often replaced as part of unit reconfiguration), and (in many cases) removal of an existing rear addition or garage that is being repurposed. Includes disposal fees, dust containment, and asbestos abatement if pre-1990 popcorn ceilings or vinyl floor tiles are present (asbestos testing and abatement adds $5K-$15K).

Structural Reframing & Underpinning ($30,000-$200,000)

Three sub-phases that swing the budget heavily:

Standard partition reframing (no underpinning, no major beams): $25K-$50K. Adding new walls, doorways, and stair openings.
Beam additions and load redistribution (where you are removing or moving load-bearing walls to create open kitchens): $20K-$60K including engineer-stamped LVL or steel beams and column packouts.
Basement underpinning (lowering basement floor 12-24" to gain ceiling height for legal apartment): $50K-$120K typical for a 1,000 sq ft footprint. Bench-footing alternative is $35K-$70K but reduces basement floor area by 6-12".

If the basement already has 7'-9" ceiling height, you can skip underpinning. If it has 6'-6" or less, underpinning is required to legally rent the basement unit.

Foundation & Waterproofing ($10,000-$45,000)

New basement entry / walkout staircase (separate entry to basement unit): $12K-$25K including excavation, retaining walls, drainage.
Waterproofing repairs at any opened foundation areas: $5K-$15K.
Weeping tile / sump pump upgrades: $3K-$10K.

Framing for New Walls, Stairs, and Demising ($30,000-$60,000)

New interior partition walls dividing units, new stair runs (most fourplex conversions add or relocate at least one stair), framing for new bathrooms and kitchens. Lumber, fasteners, and labour. Three to four weeks of carpenter time.

Fire Separation Assemblies ($25,000-$60,000)

The OBC-mandated 45-minute fire-resistance assemblies between units add real cost:

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Floor/ceiling between units: Type X 5/8" drywall on resilient channel below joists, plus mineral wool insulation between joists (acoustic + fire), plus subfloor and finished flooring above. Typically $8-$14 per sq ft of floor area between units.
Demising walls between side-by-side units: double-stud or single-stud with Type X drywall both sides, mineral wool insulation, sealed at all penetrations. $12-$22 per linear foot.
Stair enclosure walls: 45-minute rated drywall + 20-minute self-closing fire doors at each unit entrance. $4K-$9K total.
Sprinklers (NFPA 13D): required only if the building exceeds Part 9 thresholds (i.e., over three storeys above grade or over 600 m² per storey). Typical residential 4-unit conversion does NOT require sprinklers; new-build fourplexes with three full storeys above grade often DO. Add $15K-$30K if required.

Detailed breakdown in [Multiplex Fire Separation OBC Toronto](/blog/multiplex-fire-separation-obc-toronto).

Mechanical: HVAC ($25,000-$70,000)

Each unit ideally gets its own heating and cooling zone. Common 2026 configurations:

Four ductless mini-split heat pumps, one per unit: $20K-$40K total. Allows full per-unit metering and tenant-controlled comfort. Common in conversions.
One central forced-air system with four zone dampers: $15K-$28K. Cheaper but harder to bill back utilities to individual tenants.
Hybrid (heat pump + gas furnace backup): $30K-$50K. Best for cold-weather reliability but more complex.

ERV (energy recovery ventilator) typically required for code compliance: $4K-$8K per unit if separate, or one larger unit serving multiple zones.

Plumbing ($35,000-$80,000)

Four kitchens + 4-5 bathrooms means a substantial plumbing scope:

New PEX or copper supply lines to each unit: $8K-$18K.
New 3" ABS drain stacks and venting: $10K-$22K.
Hot water: either four separate tankless heaters (one per unit) at $3K-$5K each, or one large 75-gallon tank with mixing valves at $4K-$8K total, or four separate 40-gallon tanks at $1.5K-$2.5K each.
Plumbing fixtures (faucets, toilets, tubs, shower valves, kitchen sinks): $8K-$20K total across four units.
Plumbing trade permit + inspections: $1.5K-$3K.

Electrical ($25,000-$55,000)

200A or 400A service upgrade (most older bungalows have 100A; insufficient for four units): $5K-$12K including Toronto Hydro service charges.
Three or four separate sub-panels (one per unit, plus house panel for common areas): $4K-$8K.
Smart meters or sub-meters per unit (for tenant utility billing): $3K-$8K.
New circuits, outlets, switches, lighting throughout four units: $12K-$25K.
ESA permit and inspections: $800-$2,500.

For full per-unit utility separation strategy, see the [Multiplex Conversion Permits Toronto](/blog/multiplex-conversion-permits-toronto-timeline) guide.

Insulation, Drywall, Paint ($30,000-$70,000)

Insulation upgrades to bring the building to current SB-12 energy code, drywall installation throughout (significantly more linear feet than a single-family reno because of all the new partition walls), all taping, mudding, and finish painting in four units' worth of colour schemes.

Kitchens (4 × $12,000-$25,000 each = $48,000-$100,000)

Per-unit kitchen pricing:

Rental-grade IKEA-base kitchen with stock cabinets, laminate countertops, basic stainless appliances: $12K-$15K all-in.
Mid-range with quartz countertops, semi-custom cabinets, mid-grade appliances: $16K-$22K.
High-end one-bedroom kitchen with custom millwork, premium quartz, Bosch/Fisher Paykel appliances: $22K-$35K.

Most fourplex conversions use the rental-grade or mid-range tier across all four units to keep the budget on target. Budget at least $15K per unit for a credible market-rate finish.

Bathrooms (4-5 × $8,000-$18,000 each = $32,000-$90,000)

Each unit needs at least one full bathroom; two-bedroom units may have a second. Per-bathroom costs:

Standard 4-pc bath with tile shower-tub combo, basic vanity, ceramic floor: $8K-$12K.
Mid-range with frameless glass shower, quartz vanity top, designer fixtures: $12K-$16K.
Higher spec with curbless shower, heated floor, custom vanity, designer tile: $16K-$22K.

Flooring ($15,000-$35,000)

Across four units typically 1,800-2,800 total sq ft of flooring:

Luxury vinyl plank (LVP) $4-$7/sq ft installed: durable, water-resistant, 95% of rental conversions.
Engineered hardwood $8-$14/sq ft installed: upmarket positioning.
Tile in wet areas: $9-$15/sq ft installed.

Trim, Paint, Doors ($15,000-$35,000)

Interior doors (12-18 doors across four units), baseboards, casings, door hardware, finish paint throughout. Heritage Toronto homes with original trim can cost more if the trim is being preserved or replicated.

Site Work, Landscaping, Separate Entries ($20,000-$50,000)

Walkway and railings to side or rear basement entry: $5K-$15K.
Sod, planting, drainage reinstatement after construction: $3K-$10K.
Front porch repairs / new front steps if disrupted: $4K-$12K.
Bicycle parking compliance (2 spaces per residential unit): $1K-$3K.
Garbage and recycling enclosure: $1K-$3K.

Contingency (10-15% of subtotal: $35,000-$100,000)

This is non-negotiable. Toronto multiplex conversions almost always discover one or more of: hidden knob-and-tube wiring, asbestos, undersized joists, foundation cracks, or non-compliant existing plumbing. Budget 10% as a minimum, 15% if the existing house is over 70 years old.

Total: Putting It All Together

For a typical 2,400 sq ft Scarborough bungalow being converted to a fourplex with mid-range finishes, no major addition, and modest underpinning to legalize the basement:

Category	Cost
Soft costs	$80,000
Demolition + site prep	$30,000
Structural + underpinning	$90,000
Foundation + walkout	$25,000
Framing	$45,000
Fire separation	$40,000
HVAC	$45,000
Plumbing	$55,000
Electrical	$40,000
Insulation/drywall/paint	$50,000
Kitchens (4)	$72,000
Bathrooms (4)	$52,000
Flooring	$24,000
Trim/doors	$22,000
Site work	$30,000
Subtotal	$700,000
Contingency 12%	$84,000
Total	$784,000

This is a typical mid-range outcome. Stripped-back budgets with rental-grade finishes throughout and no underpinning can land at $450K-$550K. Higher-spec conversions with major rear additions, premium finishes, and full per-unit Net Zero Ready energy upgrades push to $1.0M-$1.3M.

Cost Drivers: Where the Variance Comes From

The four biggest swing factors:

1. Basement underpinning yes/no. Adds $50K-$120K but unlocks a market-rate basement unit (rental upside $1,500-$2,200/mo). Almost always cash-flow positive over 5 years.
2. Number of separate utility services. Fully separate hydro, gas, water meters per unit add $30K-$60K but allow tenants to pay their own utilities (saving $200-$400/month per unit on the landlord side).
3. Finish tier. Rental-grade vs mid-range vs premium across kitchens, bathrooms, and flooring can swing the project ±$80K-$150K with limited rental income difference at the rental-grade-to-mid-range threshold.
4. Addition or no addition. Adding a rear or third-storey addition to gain GFA pushes the total to $700K-$1.2M and is justified only when the existing envelope is too small to fit four full units.

Per-Square-Foot Math

A useful sanity check: divide the all-in renovation cost by the total finished square footage:

Quality Tier	Cost Per Sq Ft (Renovation Only)
Stripped-back rental	$180-$240/sq ft
Standard mid-range	$250-$350/sq ft
Premium / Net Zero Ready	$350-$500/sq ft
Major addition + premium	$400-$650/sq ft

For a 2,400 sq ft total finished floor area at $300/sq ft mid-range, you arrive at $720K — close to our worked example above.

Financing the Cost

Most multiplex conversions are financed through a combination of:

HELOC on the original principal residence (up to 65% LTV) for the down payment and early-stage soft costs.
Construction draw mortgage (4-5 stage draws based on completion percentage) for the bulk of hard costs.
Refinance to as-improved value at completion, typically 75-80% LTV conventional or up to 95% LTV via CMHC MLI Select if the project crosses the 5-unit threshold by adding a garden or laneway suite.

Full breakdown in [Multiplex Financing Toronto: CMHC MLI Select, BRRRR, 95% LTV](/blog/multiplex-financing-cmhc-mli-select-toronto).

Get a Realistic Cost Estimate for Your Lot

Generic per-square-foot numbers are a useful sanity check but every Toronto multiplex conversion has unique cost drivers (existing structure condition, lot constraints, neighbourhood trade rates). RenoHouse offers a free site assessment and ballpark conversion budget for any GTA property within 7 days. [Book a consultation](/services/multi-unit-aru-conversions/multiplex-conversion).