Modelling a Four-Unit Building in Halifax: What a Fourplex Feasibility Study Actually Computes

A "fourplex design simulator" promises something appealing: type in a lot size, choose a unit mix, and watch a building appear. The instinct is right — you should model a four-unit building before you commit to drawings. But a conceptual massing that ignores the governing constraints is a sketch, not a feasibility study. The variables that decide whether four units fit on a Halifax lot — and whether the project pencils — are not aesthetic preferences. They are the zoning envelope, the construction-cost basis, the municipal charges, the property-tax treatment, and the financing terms. Each of those is a published, verifiable number.

Helio is a computation-driven real estate development company in Halifax. We compute the optimal development a parcel can support and develop it end-to-end on land our clients own, with construction delivered by established builders. This article walks through the inputs a serious four-unit model has to get right in the Halifax Regional Municipality (HRM) — the same inputs that separate a real conceptual plan from a pretty rendering. Every figure below is current as of 2026-06-23 and cited to a primary source.

Step 1 — The envelope: what HRM zoning actually permits

Any honest fourplex model starts with the as-of-right envelope: what the land's zone permits by development permit, without discretionary approval. As-of-right development complies with all applicable Land Use By-law (LUB) requirements and can proceed via a development permit; a variance is only a minor relaxation of specific standards (setback, lot coverage) granted by a development officer, while larger departures require a development agreement or rezoning approved by Council [1].

The single most important change for four-unit feasibility happened in mid-2024. HRM's Housing Accelerator Fund (HAF) amendments — approved by Regional Council at second reading on May 23, 2024 and effective June 13, 2024 — permit a minimum of four dwelling units on every centrally serviced (central water and wastewater) residential lot, as-of-right, across all residential zones in HRM's serviced areas [2][3]. This is the legal basis a fourplex sits on. One deliberate exclusion: the African Nova Scotian Beechville Community was carved out of the upzoning and does not carry the four-unit allowance [4].

Inside the Regional Centre (peninsular Halifax and central Dartmouth), the relevant zones after HAF are the Established Residential zones:

• ER-1 is the lowest-density established residential zone; it does not permit townhouse or small-apartment forms, and most former ER-1 land was replaced by ER-2 and ER-3 under the June 2024 amendments [5].
• ER-2 permits single- and two-unit dwellings plus a backyard suite as-of-right; it does not permit new triplex or fourplex construction [6][7].
• ER-3 is the zone that carries a true fourplex. It permits up to eight dwelling units per lot, lot-size dependent — single, two-, three-, and four-unit dwellings, small multi-unit buildings (5–8 units), and townhouses (max 8 units, max 64 m building width) [8].

If your model places a four-unit building on a Regional Centre lot, ER-3 is almost always the zone that supports it. ER-2 will not — and modelling a fourplex on ER-2 land is exactly the kind of silent error a generic simulator produces.

The ER-3 built-form constraints your model must respect

A fourplex is not just "four units." It has to fit inside the by-law's physical envelope. In ER-3:

• Maximum building height is 11 metres, with a 3-metre exemption for a pitched roof or attic unit (so up to roughly 14 m with a sloped roof) [9]. Note: older blog content — including some of Helio's own legacy material — cited 12 m. The official maximum is 11 m.
• Lot coverage is capped at 40% (single-unit), 50% (other uses on lots over 325 m²), or 60% (lots of 325 m² or smaller) [10].
• Minimum lot frontage is 10.7 m for one-to-four-unit and multi-unit dwellings [10].
• Minimum lot area for 1–4 unit dwellings is 325 m²; unit yield scales with lot size up to the eight-unit maximum [11].
• Maximum bedrooms scale with unit count — a four-unit dwelling is capped at 12 bedrooms (single-unit 6, two-unit 8, three-unit 10, four-unit 12, and so on up to 20 at eight units) [12].

That last constraint is the one most "design simulators" miss entirely: in ER-3, you cannot freely choose unit mix. Four three-bedroom units (12 bedrooms) sits exactly at the cap; you cannot then add a den counted as a bedroom in any unit. The bedroom ceiling is a real input.

Outside the Regional Centre, in the broader Urban Service Area, the four-unit allowance comes through amended low-density (R-1/R-2) zones, and minimum lot size remains zone-specific — there is no single HRM-wide minimum [13]. Always confirm the exact parcel's zone and per-parcel height through HRM's ExploreHRM mapping and the applicable LUB before relying on any modelled envelope.

Step 2 — The construction-cost basis

Once the envelope is fixed, the model needs a defensible cost basis. Helio publishes no price of its own; instead we anchor to published cost data. The most authoritative Halifax-basis figure for small multi-unit buildings is CMHC's Housing Design Catalogue construction-cost estimates (Class-B estimates by Vermeulens, Halifax location basis, Q1-2025).

On that basis, hard construction cost for a small multi-unit building runs roughly $236,000–$358,000 per unit for a fourplex, with sixplexes around $217,000–$271,000 and stacked townhouses around $260,000–$387,000 per unit [14]. On a per-square-foot basis, small multi-unit (4–6 units) hard cost is roughly $223–$345/sq ft [15].

The scope of those numbers matters more than the numbers themselves. These are hard costs only: they include the general contractor's overhead and profit but exclude land, the cost of borrowing, soft costs (design, engineering, permits), and the owner/developer's overhead and profit. CMHC's own guidance is to add a 5–10% contingency and adjust for inflation and exact location [16]. A single all-in "$ per unit" figure quoted without that caveat is misleading — which is precisely why a feasibility model layers these costs explicitly rather than reporting one headline number.

For directional escalation: Statistics Canada's Building Construction Price Index shows Halifax residential construction prices rose 3.9% year-over-year in Q4 2025 (low-rise apartments +4.0%) [17], and the 15-CMA residential composite rose 2.8% year-over-year in Q1 2026 [18]. Adjust the Q1-2025 CMHC figures forward accordingly. As a secondary cross-reference, Altus Group's 2025 Canadian Cost Guide prices Halifax wood-frame construction at roughly $125–$170/sq ft on an asset-class shell basis — a narrower scope than CMHC's all-in catalogue figures, useful only as a corroborating range [19].

Step 3 — Municipal charges and HST

Two categories of cost that simulators almost never model — and that materially change the per-unit math — are development charges and tax.

Halifax Water Regional Development Charge (RDC). Effective April 1, 2024 and frozen at 2023 levels under an HRM Charter amendment, the RDC for a multiple-unit dwelling is $5,405.81 per unit ($1,290.77 water + $4,115.04 wastewater); for single-unit dwellings and townhouses it is $8,048.66 per unit [20]. For a four-unit building taxed as a multiple-unit dwelling, that is roughly $21,623 in RDC before anything is built. Note that an RDC increase (reported at ~16% for 2025/26 and ~17.6% for 2026/27) has been under UARB and stakeholder engagement, so verify the current rate at the time you model [21].

HRM building permit fee. For new construction of residential buildings of four units or fewer, HRM charges per square metre of floor area — $4.04/m² at or above average finished grade, $3.36/m² for shallow below-grade floors, and $1.35/m² for deeper basements and garages, with a $31.25 minimum (effective April 1, 2024) [22]. A demolition permit, if you are replacing an existing structure, is a separate $62.50 [23].

HST. Nova Scotia's HST is 14% (5% federal + 9% provincial), reduced from 15% effective April 1, 2025 [24]. It applies to new construction on top of base hard-construction cost. Critically for rental, long-term residential rent is a GST/HST-exempt supply — no HST is charged on the rent, and the landlord cannot claim input tax credits on related inputs [25].

Step 4 — How a fourplex is taxed and financed

A four-unit building's downstream economics — the part a "simulator" never shows — depend on tax class and available financing.

Property tax class. Apartment and condominium buildings in Nova Scotia are classified as Residential property regardless of unit count, and taxed at the municipal residential rate, not the commercial rate [26]. HRM's 2025 residential general rate is roughly $0.654–$0.687 per $100 of assessment (suburban/rural to urban), plus a residential climate-action rate and any local area rates [27]. One common confusion to avoid in the model: the four-unit threshold relates to the Capped Assessment Program (CAP), not the tax class. CAP limits annual taxable-assessment increases for owner-occupied properties with fewer than four units (the 2026 CAP rate is 2.6%); a four-unit building, new construction, and non-owner-occupied property are not CAP-eligible — but they remain residential class at the residential rate [28].

Financing the rental. Two distinct CMHC instruments shape a purpose-built rental fourplex's capital stack, and they are frequently conflated:

• MLI Select is CMHC's multi-unit mortgage loan insurance, which awards points across affordability, accessibility, and energy efficiency to unlock reduced premiums, higher leverage, and longer amortization. It requires a minimum of five units [29][30]. A four-unit building does not meet the minimum — which is a real reason developers sometimes model five or six units instead of four when the lot and zone allow it.
• The Apartment Construction Loan Program (ACLP) — the renamed Rental Construction Financing initiative — is a direct low-interest construction loan for the residential component, also with a minimum of five units [31][32]. ACLP and MLI Select are different instruments and can be used together, but neither reaches a strict four-unit project [33].

This is one of the most consequential findings a feasibility model surfaces: on an ER-3 lot that can carry up to eight units, the gap between four units (no MLI Select, no ACLP) and five-plus units (both available) can change the financing entirely. The "design" question and the "feasibility" question are inseparable.

Tax on the building over time. A rental building acquired after 1987 is generally Capital Cost Allowance Class 1 at 4% declining-balance [34], but eligible new purpose-built rental qualifies for an accelerated 10% CCA rate where construction begins on or after April 16, 2024 and before 2031 [35]. And new purpose-built rental can qualify for the federal Purpose-Built Rental Housing (PBRH) rebate — 100% of the GST / 5% federal part of HST, up to $35,000 per unit — with Nova Scotia mirroring it at 100% of the 9% provincial part [36][37]. A four-unit building that qualifies as purpose-built rental can therefore recover essentially all the HST on construction; one held as condo or owner-occupied falls back to the more limited New Residential Rental Property rebate (36%, max $6,300/unit, nil above $450,000 FMV) [38]. The tenure decision is a tax decision.

What a real model produces

Put together, a credible four-unit feasibility model isn't a rendering — it's a set of linked computations: the governing zone (ER-3 in the Regional Centre), the physical envelope (11 m height, 325 m² minimum lot, lot-coverage cap, 12-bedroom ceiling), the hard-cost basis (CMHC Halifax, escalated by StatCan), the charges (RDC, permit fee, HST), the tax treatment (residential class, CCA, PBRH rebate), and the financing reality (the five-unit floor on MLI Select and ACLP).

That is the difference between asking "what does a fourplex look like?" and "what is the optimal building this parcel can support, and does it pencil?" The second question is the one worth answering before any drawing is commissioned — and it is the question Helio computes for the land our clients already own. None of the inputs above are proprietary; they are public, and they are checkable against the sources below.

All regulatory, tax, zoning, cost, and program figures above are current as of 2026-06-23 and may change. Confirm zone, height, and lot standards for a specific parcel through HRM's ExploreHRM and the applicable Land Use By-law before relying on any modelled result.

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Sources

1. Halifax Regional Municipality Charter (Nova Scotia) — as-of-right vs variance administration. https://nslegislature.ca/sites/default/files/legc/statutes/halifax%20regional%20municipality%20charter.pdf
2. Halifax Regional Municipality — Recent changes to planning documents for housing (Housing Accelerator Fund). https://www.halifax.ca/about-halifax/regional-community-planning/housing-accelerator-fund/urgent-changes-planning-0
3. HRM — Housing Accelerator Fund (HAF) program page. https://www.halifax.ca/about-halifax/regional-community-planning/housing-accelerator-fund
4. HRM — HAF / Timberlea-Lakeside-Beechville SMPS & LUB amendments (June 2024). https://www.halifax.ca/about-halifax/regional-community-planning/housing-accelerator-fund/urgent-changes-planning-0
5. HRM — HAF Amendments: Permitted Uses, Regional Centre Established Residential Zones (ER Zones Fact Sheet, June 2024). https://cdn.halifax.ca/sites/default/files/documents/about-the-city/regional-community-planning/er-zones-fact-sheet-june-2024.pdf
6. HRM — ER Zones Fact Sheet (June 2024), ER-2 permitted uses. https://cdn.halifax.ca/sites/default/files/documents/about-the-city/regional-community-planning/er-zones-fact-sheet-june-2024.pdf
7. HRM — ER Zones Fact Sheet (June 2024), ER-2 (single/two-unit + backyard suite; no triplex/fourplex). https://cdn.halifax.ca/sites/default/files/documents/about-the-city/regional-community-planning/er-zones-fact-sheet-june-2024.pdf
8. HRM — ER Zones Fact Sheet (June 2024), ER-3 up to 8 units. https://cdn.halifax.ca/sites/default/files/documents/about-the-city/regional-community-planning/er-zones-fact-sheet-june-2024.pdf
9. HRM — ER Zones Fact Sheet (June 2024), ER-3 height 11 m + 3 m pitched-roof exemption. https://cdn.halifax.ca/sites/default/files/documents/about-the-city/regional-community-planning/er-zones-fact-sheet-june-2024.pdf
10. HRM — ER Zones Fact Sheet (June 2024), ER-3 lot coverage and frontage. https://cdn.halifax.ca/sites/default/files/documents/about-the-city/regional-community-planning/er-zones-fact-sheet-june-2024.pdf
11. HRM — ER Zones Fact Sheet (June 2024), ER-3 minimum lot area 325 m² for 1–4 units. https://cdn.halifax.ca/sites/default/files/documents/about-the-city/regional-community-planning/er-zones-fact-sheet-june-2024.pdf
12. HRM — ER Zones Fact Sheet (June 2024), maximum bedrooms by unit count. https://cdn.halifax.ca/sites/default/files/documents/about-the-city/regional-community-planning/er-zones-fact-sheet-june-2024.pdf
13. HRM — Community Plan Areas / Land Use By-laws (zone-specific minimum lot size). https://www.halifax.ca/about-halifax/regional-community-planning/community-plan-areas
14. CMHC — Housing Design Catalogue, Construction Cost Estimate Summary (Atlantic), Halifax Q1-2025 per-unit hard costs. https://assets.cmhc-schl.gc.ca/sites/housing%20catalog/resources/hdc-construction-cost-estimate-summary-atlantic-en.pdf
15. CMHC — Housing Design Catalogue (Atlantic), Halifax per-sq-ft hard costs, small multi-unit. https://assets.cmhc-schl.gc.ca/sites/housing%20catalog/resources/hdc-construction-cost-estimate-summary-atlantic-en.pdf
16. CMHC — Housing Design Catalogue (Atlantic), costing notes (hard costs only; +5–10% contingency; excludes land/financing/soft/developer profit). https://assets.cmhc-schl.gc.ca/sites/housing%20catalog/resources/hdc-construction-cost-estimate-summary-atlantic-en.pdf
17. Nova Scotia Department of Finance — Building Construction Price Index Q4 2025 (reporting StatCan Table 18-10-0289-01). https://novascotia.ca/finance/statistics/archive_news.asp?id=21693&dg=&df=&dto=0&dti=3
18. Statistics Canada — The Daily: Building construction price indexes, Q1 2026. https://www150.statcan.gc.ca/n1/daily-quotidien/260428/dq260428b-eng.htm
19. Altus Group — 2025 Canadian Cost Guide (Halifax wood-frame, asset-class basis; secondary cross-reference). https://www.altusgroup.com/featured-insights/canadian-cost-guide/
20. Halifax Water — Regional Development Charge (current rate schedule). https://www.halifaxwater.ca/regional-development-charge
21. Halifax Water — Regional Development Charge Interested Parties Engagement 2025. https://www.halifaxwater.ca/RDC-engagement
22. Halifax Regional Municipality — Permit Fees (License, Permit and Processing Fees Administrative Order #15). https://www.halifax.ca/home-property/building-development-permits/permit-fees
23. Halifax Regional Municipality — Permit Fees (demolition permit). https://www.halifax.ca/home-property/building-development-permits/permit-fees
24. Canada Revenue Agency — GST/HST Notice 342 (Nova Scotia HST Rate Decrease to 14%). https://www.canada.ca/en/revenue-agency/services/forms-publications/publications/notice342/nova-scotia-hst-rate-decrease-questions-answers-general-transitional-rules-personal-property-services.html
25. Excise Tax Act, RSC 1985 c. E-15, Schedule V, Part I, para 6 (long-term residential rent exempt). https://laws-lois.justice.gc.ca/eng/acts/e-15/page-120.html
26. PVSC — Property Classification (apartments/condominiums are Residential class regardless of unit count). https://www.pvsc.ca/understand-your-assessment/assessment-in-nova-scotia/mass-appraisal/classification
27. Halifax — Tax Rates (2025 residential general rate). https://www.halifax.ca/home-property/property-taxes/tax-rates
28. PVSC — Capped Assessment Program (2026 CAP 2.6%; eligibility <4 units, owner-occupied). https://www.pvsc.ca/understand-your-assessment/capped-assessment-program
29. CMHC — MLI Select (points across affordability, accessibility, climate). https://www.cmhc-schl.gc.ca/professionals/project-funding-and-mortgage-financing/mortgage-loan-insurance/multi-unit-insurance/mliselect
30. CMHC — MLI Select (minimum 5 units). https://www.cmhc-schl.gc.ca/professionals/project-funding-and-mortgage-financing/mortgage-loan-insurance/multi-unit-insurance/mliselect
31. CMHC — Apartment Construction Loan Program (formerly RCFi). https://www.cmhc-schl.gc.ca/professionals/project-funding-and-mortgage-financing/funding-programs/all-funding-programs/apartment-construction-loan-program
32. CMHC — ACLP: Standard Rental Housing (minimum 5 units). https://www.cmhc-schl.gc.ca/professionals/project-funding-and-mortgage-financing/funding-programs/all-funding-programs/apartment-construction-loan-program/standard-rental-housing
33. CMHC — Mortgage Loan Insurance for Multi-Unit and Rental Housing (ACLP vs MLI Select distinction). https://www.cmhc-schl.gc.ca/professionals/project-funding-and-mortgage-financing/mortgage-loan-insurance/multi-unit-insurance
34. Canada Revenue Agency — Classes of depreciable property (Class 1, 4% buildings). https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/sole-proprietorships-partnerships/report-business-income-expenses/claiming-capital-cost-allowance/classes-depreciable-property.html
35. Budget 2024 — Tax Measures: Supplementary Information (Accelerated 10% CCA for Purpose-Built Rental Housing). https://www.budget.canada.ca/2024/report-rapport/tm-mf-en.html
36. Canada Revenue Agency — GST/HST Purpose-Built Rental Housing (PBRH) Rebate (100% federal, max $35,000/unit). https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/gst-hst-businesses/gst-hst-rebates/purpose-built-rental-housing.html
37. Government of Nova Scotia — Department of Finance, Purpose-Built Rental Housing Rebate (100% of provincial part). https://novascotia.ca/finance/en/home/taxation/tax101/harmonizedsalestax/purpose-built-rental-housing-rebate.html
38. Canada Revenue Agency — GST/HST New Residential Rental Property Rebate (36%, max $6,300/unit). https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/gst-hst-businesses/gst-hst-rebates/new-residential-rental-property-rebate.html