Multiplex Framing Cost in the GTA (2026): Duplex, Triplex, Fourplex, Six-Plex

Multiplex framing in the GTA runs $15 to $32 per square foot installed for wood framing and $17 to $32 per square foot for cold-formed steel in 2026. Framing accounts for roughly 18 to 24 percent of total multiplex build cost. On a typical 4,000 sq ft fourplex, that works out to a $60,000 to $130,000 framing scope. The fifth unit is usually the cheapest unit you will ever build — because of financing, not framing.

Framing cost by multiplex type (2026)

The default assumption most first-time multiplex builders carry — that cost per square foot drops as unit count rises — mostly does not hold for framing. Fire-rated party walls, continuous acoustic separation, and engineered floor systems at each unit boundary mean the framing $/sq ft is flatter across duplex, triplex, fourplex, and six-plex than owners expect.

• Duplex (2 units, typical 2,500–3,500 sq ft): framing labour $37,500 to $70,000, or $15–$20/sq ft
• Triplex (3 units, typical 3,200–4,500 sq ft): framing labour $48,000 to $90,000, or $15–$20/sq ft
• Fourplex (4 units, typical 4,000–5,500 sq ft): framing labour $60,000 to $130,000, or $15–$24/sq ft
• Six-plex (6 units, typical 5,500–7,500 sq ft): framing labour $85,000 to $180,000, or $15–$24/sq ft

Framing cost as a share of total build cost: 18 to 24 percent for new-build multiplexes in the GTA. If a builder quotes you a framing scope materially below or above that band, ask for the breakdown — the gap usually reflects what is included in "framing" (floor systems, sheathing, exterior walls, interior walls, stairs) versus what is listed separately.

Total build cost per square foot (benchmarks)

Framing is one line in a much bigger stack. Here are the total-build benchmarks to keep the framing number in context:

• Fourplex new infill build: $340 to $400/sq ft all-in
• Six-plex new infill build: $340 to $420/sq ft all-in (scarcer data; post-2025 bylaw expansion)
• Fourplex conversion of an existing single-family home: $130 to $180/sq ft for the retained-layout portion, $340 to $400/sq ft for any addition
• Total fourplex project cost range: $600,000 to $1,200,000+ depending on size, finish level, and whether any units are rooftop additions

On a 4,500 sq ft fourplex new build at $375/sq ft, the framing scope is roughly $75,000 to $90,000 — approximately 20 percent of a $1.69 million total.

Wood versus cold-formed steel (CFS) framing

Cold-formed steel is used on about one in four GTA multiplex projects, and the decision is almost never driven by the Ontario Building Code on its own. At three storeys and 600 square metres or less of building area, you are inside Part 9 of the OBC, which allows combustible construction. Six-plexes in Toronto are typically designed to stay within Part 9 — so wood remains code-compliant at 6 units in most cases.

What actually drives the wood-versus-steel decision:

• Insurance premiums. Non-combustible (steel) construction saves roughly $100,000+ in insurance over the life of a typical 5-to-6 storey residential stack, and 20 to 30 percent on builder’s-risk premiums during construction. On smaller multiplexes (3 storeys or less) the delta narrows but is still measurable.
• Speed. Panelized CFS typically installs 30 to 50 percent faster than site-framed wood. On a financed build with a construction loan, that time saving often offsets the material premium entirely.
• Part 3 transitions. If the design exceeds 3 storeys or 600 m², the OBC jumps to Part 3 — sprinklers mandatory, engineered fire-resistance design, and encapsulated mass timber or non-combustible becomes the practical choice.
• Owner preference for non-combustible exterior walls on fire-exposed party walls with reduced limiting distance to property lines

Hard numbers from a directly comparable 5-storey mixed-use benchmark study: wood framing at $21.90/sq ft versus CFS at $26.50/sq ft — about a 21 percent premium on the framing scope alone. At the whole-building level, that delta shrinks to roughly 3 percent. Factor insurance and speed in, and the real-world total-cost delta is often under 1 percent.

The OBC Part 9 vs Part 3 threshold you need to know

The Ontario Building Code splits residential construction into two worlds. Which one your multiplex falls into changes the cost stack materially:

• Part 9 (Housing and Small Buildings): applies when the building is 3 storeys or less AND 600 square metres or less. Allows combustible wood-frame construction, prescriptive designs, simpler inspections. Duplexes, triplexes, most fourplexes, and six-plexes that stay under these limits live here.
• Part 3 (Large Buildings): kicks in past either threshold. Sprinklers mandatory, engineered fire-resistance rating (FRR) design required, non-combustible construction (or encapsulated mass timber under specific rules), independent commissioning. Materially higher cost stack.

For a builder optimizing the unit-economics on a 6-plex, the design usually stays at 3 storeys plus basement, under 600 m² building area, and stays in Part 9 — keeping wood framing, prescriptive assemblies, and a normal inspection cadence. The moment you add a fourth storey or cross 600 m², the project absorbs tens of thousands in additional engineering, fire-rated materials, and sprinkler infrastructure.

Fire separation, acoustic, and structural elements that drive framing cost

Three code-driven elements set the floor on multiplex framing cost. These are the assemblies that separate the "cheapest possible framing scope" from the real one:

• 1-hour fire-rated party walls — required under OBC 9.10.9 and 9.10.11 between stacked or side-by-side dwelling units, continuous from footings to the underside of the roof deck. The 2024 OBC update standardized 5/8" Type X drywall for multiplex fire separations.
• STC 50 acoustic separation minimum between units (OBC requirement). A single-stud 1-hour resilient-channel partition typically hits STC 50 to 54. Double-stud walls with laminated gypsum push STC 55+. On quality-focused multiplex builds, going from STC 50 to STC 55 adds roughly $3 to $6/sq ft on inter-unit walls.
• Steel moment frames — often required at ground-floor open plans where removing interior load-bearing walls (for parking or a double-height living space) requires a steel beam-and-column frame. Typical moment-frame scope on a GTA fourplex: $8,000 to $25,000 depending on span and storey count.

Why the 5th unit is the cheapest unit you will ever build

The single biggest lever in multiplex unit economics has nothing to do with framing. It is CMHC MLI Select financing, which unlocks at 5 or more rental units. The rough shape:

• 4-unit multiplex: 20 percent down, 25-year amortization, roughly 5.0 percent conventional mortgage rate (2026)
• 5+ unit multiplex (CMHC MLI Select): as low as 5 percent down, 50-year amortization, roughly 4.25 percent CMHC-insured rate

On a $2.5 million project, adding the fifth unit (and optimizing for MLI Select) typically reduces annual debt service by approximately $9,600, even though you are borrowing roughly $375,000 more capital. CMHC’s MLI Select program has Debt Service Coverage Ratio floors and a 50/70/100 point system that unlocks additional premium discounts at higher energy efficiency, affordability, and accessibility tiers.

Development charges amplify the same pattern in Toronto. The City waived development charges on the first 6 units of a multiplex in 2025 — previously those DCs could total $200,000 to $270,000 for a 6-unit project. Unit 7 and beyond is where DCs restart at roughly $50,000 per unit.

Toronto’s as-of-right multiplex bylaw — what changed

The Toronto multiplex landscape has two bylaw milestones that reshape the construction economics:

• May 2023: fourplexes (up to 4 units) permitted as-of-right city-wide, no variance required when within bylaw parameters
• June 2025: six-plexes permitted as-of-right in 9 wards covering the Toronto and East York District plus Ward 23. Other wards require a Minor Variance or rezoning

The permit pipeline result: 779 multiplex building permits issued since the 2023 bylaw, with roughly 73 percent classified as conversions of existing homes and 27 percent as new builds. Approximately 76 percent of the permitted multiplex activity is concentrated west of Yonge Street. For builders, the practical read is that 4-unit projects have essentially no zoning risk across the city, while 6-unit projects remain neighbourhood-specific until the ward-by-ward expansion completes.

Timeline — framing stage and full-project

• Building permit wait (Toronto & East York): 4–6 weeks for a complete, compliant submission; 8–12 weeks for applications with comments or variance needs
• Design and permitting end-to-end: 6–12 months
• Framing stage (fourplex): 4–8 weeks on site
• Framing stage (six-plex): 6–10 weeks on site
• Full construction (fourplex): 8–12 months from permit to occupancy
• Full construction (six-plex): 12–18 months from permit to occupancy

How Konstruction Group approaches multiplex framing

We have completed more than 500 construction projects across the GTA since 2011, with a focused specialty in multi-unit framing, structural steel, insulation, and drywall/finishes. The operational model matters here:

• In-house framing crews — we do not subcontract rough framing. A single coordination point from footings through roof sheathing keeps schedule discipline tight and eliminates the "subtrade blame loop" that stalls framing stages on many multiplex sites.
• Integrated structural steel and welding — we fabricate and install moment frames, beams, and columns on our own sites, which removes the 2-to-4-week lag that typically shows up when steel is quoted, fabricated, and installed by a separate contractor.
• Insulation and drywall under the same contract — the three trades most responsible for acoustic and fire separation performance (framing, insulation, drywall/finishes) are coordinated as one scope. STC and FRR performance is verified by the same team that built the assembly.
• Scope discipline on line-item pricing — framing is quoted as framing. Fire separation assemblies, acoustic upgrades, moment-frame steel, and engineered floor systems are priced as separate line items so the homeowner or developer can see where cost concentrates.

Our typical multiplex framing scope for a 4-unit new build in the GTA runs $60,000 to $130,000 depending on floor area, storey count, and whether steel moment frames are in scope. That quote bundles rough framing, exterior wall sheathing, engineered floor systems, stairs, and interior load-bearing framing.

Next steps

If you are weighing a multiplex build or conversion in the GTA:

1. Confirm whether your target unit count (4 or 6) is as-of-right in your ward or needs a variance
2. Model the economics with and without the 5th unit — the CMHC MLI Select unlock often changes the answer
3. Decide the wood-versus-CFS question on insurance and speed, not code compliance (most Toronto multiplexes are Part 9 and wood-compliant)
4. Get framing quotes that separate fire separation assemblies and moment-frame steel from the core framing scope

Request a detailed multiplex framing quote from Konstruction Group — we provide a line-item breakdown covering framing, fire separation, acoustic upgrades, and any required structural steel.