ImmoMulti — direct buyer of multi-unit properties on the North Shore — tells every owner who moves from a fourplex to a 5-unit building the same thing: financing a building of 5 or more units has almost nothing in common with financing a plex. It isn't just a matter of size. In Canada, the moment a building has five units or more, it leaves the world of the residential mortgage and enters that of the commercial multi-residential loan. Down payment, qualification, ratios, amortization, required documents: it all changes. This guide explains concretely why crossing from 4 to 5 units flips your financing — and how to prepare for it.
Why does 5 units change everything in financing?
In Canada, the residential mortgage boundary stops at 4 units. A property of 1 to 4 units qualifies for standard residential loans. From 5 units onward, it becomes a commercial multi-residential building: the lender qualifies the building first by its income, not just your personal file. CMHC uses the same line between its 1-to-4-unit loans and its multi-unit programs (5 units and up).
The most important dividing line in rental real estate isn't between the duplex and the triplex, nor between the triplex and the fourplex. It sits between 4 units and 5 units. Below it, you're in residential territory: the lender looks mostly at your income, your credit and your personal debt capacity, much like for a house. The fourplex is the "last" building financeable as residential.
From the fifth unit, the logic flips. The building is treated as a business that produces income. The lender first wants to know whether the building itself generates enough net income to repay the debt. This is the world of commercial multi-residential credit, with its own lenders, its own rules and its own timelines. The CMHC applies the same boundary: its insurance products for 1-to-4-unit buildings are distinct from its programs for buildings of 5 or more units.
Source: CMHC — Mortgage Loan Insurance (1-4 unit and multi-unit products).
What are the 5 differences between a residential and a commercial loan?
A residential loan (1-4 units) qualifies the borrower; a commercial loan (5+ units) qualifies the building first by its net income. Commercial generally requires a higher down payment, relies on the debt service coverage ratio, demands a commercial appraisal and building financial statements, but can offer longer amortization.
| Criterion | Residential (1 to 4 units) | Commercial (5 units and up) |
|---|---|---|
| Qualification basis | Borrower's income and credit | Building's net operating income (+ borrower's file) |
| Down payment (conventional) | Lower | Generally higher (often ~25%+) |
| Key ratio | Debt-service ratios (GDS/TDS) | Debt service coverage ratio (DSCR) |
| Amortization | Up to 25-30 years | Often longer (up to 40, even 50 years with MLI Select) |
| Required appraisal | Residential appraisal | Commercial appraisal (economic value) |
These differences aren't mere administrative nuances: they determine how much capital you must lock in and whether the building qualifies at all. Exact parameters (rate, ratios, insurance premium) vary by lender, insurer and the building's profile; always confirm the figures with a professional before making an offer.
How much down payment for a building of 5 or more units?
For a conventional (uninsured) commercial loan on a 5-or-more-unit building, the down payment is generally higher than in residential — often in the range of 25% or more of value. With CMHC multi-unit mortgage loan insurance, the eligible loan-to-value can be higher, which lowers the required down payment, in exchange for an insurance premium.
This is often shock number one for the fourplex owner eyeing a bigger building: the down payment climbs. Where an owner-occupied plex could be financed with a modest down payment, a commercial building of 5 or more units typically demands a larger share of capital in conventional lending. The lender's reasoning is simple: the bigger the building, the greater the exposure to rental risk, so it wants more of a cushion.
This is precisely where CMHC mortgage loan insurance becomes appealing: by insuring the loan, it often allows a higher loan-to-value (thus a lower down payment), a better rate and a longer amortization. The trade-off is an insurance premium and meeting the program criteria. To compare insured and uninsured scenarios, our financing comparator estimates the effect on the monthly payment.
How does the debt service coverage ratio work?
The debt service coverage ratio (DSCR) = annual net operating income ÷ annual debt service (principal + interest). A DSCR of 1.20 means the building generates $1.20 of net income for every $1 of mortgage payment. Commercial lenders generally require a minimum DSCR (often 1.20 to 1.30 for conventional loans); CMHC-insured loans may accept a lower ratio.
In residential, the lender calculates your gross and total debt service ratios (GDS/TDS) from your income. In commercial, it looks at the building first through the debt service coverage ratio (DSCR). The formula is straightforward:
The DSCR formula
- DSCR = Net operating income (NOI) ÷ Debt service (principal + interest)
- NOI = rental income minus operating expenses (taxes, insurance, maintenance, management, vacancy), before the mortgage.
- A DSCR ≥ 1 means the building "pays for itself"; below 1, it operates at a deficit.
Concretely, if a 6-unit building produces $60,000 of NOI and its annual debt service is $50,000, its DSCR is 1.20. Most commercial lenders want a cushion: a minimum DSCR around 1.20 to 1.30 is common in conventional lending. A longer amortization lowers the annual payment, raises the DSCR and therefore helps the building qualify — one of the major advantages of CMHC-insured loans. To master the NOI and yield calculation, see our guide to calculating a multiplex's return.
How does CMHC multi-unit insurance work for a 5-or-more-unit building?
CMHC insures loans on buildings of 5 or more units through its multi-unit programs. An insured loan often offers a better rate, a higher loan-to-value and a longer amortization, in exchange for a premium. The MLI Select program adds incentives (amortizations that can reach up to 50 years depending on eligibility) tied to energy efficiency, affordability and accessibility.
CMHC mortgage loan insurance is not mandatory for a commercial building, but it often transforms the economics of the project. By reducing the lender's risk, it unlocks better terms. The flagship program for new or existing buildings is MLI Select (Multi-Unit Loan Insurance Select), which grants increasing benefits — reduced down payment, extended amortization — based on a points system covering energy efficiency, accessibility and housing affordability. We detailed its mechanics in our CMHC MLI Select financing guide.
Careful: "eligible" doesn't mean "automatic"
A building of 5 or more units is eligible for CMHC's multi-unit programs, but it must meet the criteria (building condition, income, ratios, borrower's file). A fourplex converted to 5 units without permits or compliance may be refused. Always verify eligibility before buying.
Source: CMHC — Multi-Unit Mortgage Loan Insurance and MLI Select.
What mistakes should you avoid going from 4 to 5 units?
The most common traps: believing a 5-unit building finances like a plex, underestimating the commercial down payment, ignoring the DSCR, adding a 5th unit without permits or compliance, and using a residential broker without access to commercial lenders. Each of these mistakes can derail qualification.
- Thinking "5 is like 4": the jump to commercial changes the down payment, ratios and timelines. Budget accordingly from the purchase offer.
- Underestimating the down payment: in conventional lending, plan for a higher capital share than in residential. Check whether a CMHC structure can reduce it.
- Ignoring the DSCR: if the building's net income doesn't cover the debt service with the required cushion, the loan won't pass — regardless of your personal file.
- Adding a non-compliant unit: converting a fourplex to 5 units without permits or a certificate can exclude you from commercial financing and CMHC insurance.
- The wrong broker: a commercial multi-unit mortgage broker has access to the right lenders and knows how to assemble the file (leases, financial statements, appraisal). A residential generalist often does not.
The takeaway: the moment you target a building of 5 or more units, prepare to think like a commercial investor, not a plex buyer. The number of units isn't just a statistic — it's the variable that decides the very nature of your loan. If you already own such a building and are torn between keeping, refinancing or selling it, our team can give you a numbers-based read of its economic value.
ImmoMulti: direct buyer of multi-unit properties on the North Shore
Whether your building has 5, 8 or 12 units, we can send you a direct offer based on its economic value — no broker, no commission, in full confidentiality. Get a proposal within 48 hours.
To dig deeper into how rates and the financing structure affect the purchase value of a larger building, see our analysis of 2026 multiplex mortgage rates, and if you're considering holding the building through a corporation, weigh the trade-offs before deciding.
