What Is Multi-Family Property?
Multi-family means 2+ units. A duplex. A 12-unit walk-up. A 200-unit garden complex. The key advantage: when one unit goes vacant, you still collect rent on the rest. A 4-plex with one empty unit loses 25% of income; a single-family rental with one empty unit loses 100%. Financing splits at 5 units: 1–4 units use conventional or FHA; 5+ use commercial loans with DSCR underwriting. The Small Multifamily guide and Real Estate Investing guide cover the full spectrum.
A multi-family property is residential real estate with two or more units under one roof or on one parcel — duplexes, triplexes, fourplexes, and larger apartment buildings. More units mean diversified tenant risk and often stronger cash flow per dollar invested.
At a Glance
- What it is: 2+ housing units in one property — duplex through large apartment buildings
- Why it matters: Vacancy risk spreads across units; one empty unit doesn't zero out income
- Financing split: 1–4 units = residential loans; 5+ units = commercial loans, DSCR underwriting
- Operating expense ratio: Typically 38–45% of gross for 5+ units (vs. 25–35% for SFR)
- Scale path: Many investors go SFR → small multifamily (2–4) → larger (5–24) → syndication
How It Works
Unit count defines the game. Two to four units: you're still in residential financing. Conventional, FHA (if you house hack), 30-year fixed. Five units and up: commercial territory. DSCR — debt service coverage ratio — matters. Lenders want 1.2x–1.25x minimum. They care about the property's NOI, not your W-2. Loan terms shorten: 5, 7, 10 years with balloons. See the Financing guide.
Vacancy math. A duplex with one vacancy: you lose 50% of that property's rent. A 12-unit with one vacancy: you lose 8.3%. The more units, the more the law of large numbers helps. Vacancy rates still apply — budget 5–8% for stable markets, 8–12% for weaker ones — but the impact of any single turnover shrinks.
Operating expenses scale differently. Operating expenses on multifamily run 38–45% of gross for 5+ units. Why higher than single-family? Landlord-paid utilities (water, trash, sometimes gas), shared amenities (laundry, common areas), more units to maintain, professional management. The 50% Rule is a screening tool; build a line-item budget for real underwriting. NOI = gross income minus vacancy minus OpEx. Cap rate = NOI ÷ value.
Value-add plays. Buy a 16-unit with deferred maintenance. Renovate units, raise rents. NOI goes up. Refinance at the new value and pull capital out. That's the BRRRR model scaled to multifamily. Or buy stabilized, collect cash flow, and hold. The BRRRR Strategy guide and Small Multifamily guide cover both paths.
Real-World Example
Nina: 8-unit in Denver.
Nina bought an 8-unit building in Denver's Cole neighborhood for $1.24 million in 2024. Each unit rented for $1,400 — $11,200/month gross, $134,400/year. She put 25% down ($310,000) and got a 7-year commercial loan at 6.5% with a 25-year amortization. Monthly debt service: $5,847.
Her operating expenses ran 42% of gross:
- Property taxes: $14,880
- Insurance: $8,400
- Water, trash, sewer (landlord-paid): $9,600
- Maintenance and repairs: $16,800
- Property management (6%): $8,064
- Vacancy reserve (6%): $8,064
- Reserves and misc: $4,200
Total OpEx: $70,008. Effective gross (after 6% vacancy): $126,336. NOI: $56,328. Cap rate: 4.5%. Cash flow after debt service: $1,028/month. Cash-on-cash return: 4.0%. Thin, but she's banking on rent growth and appreciation. Denver's rent growth ran 4.2% in 2023. One unit turned over; she raised it from $1,350 to $1,475. That's $1,500/year in extra NOI — $30,000 in market value at a 5% cap.
Pros & Cons
- Vacancy risk spreads — one empty unit doesn't zero out income
- Cash flow per dollar invested often beats single-family
- Professional property management scales better; 6–8% of rent vs. 8–10% on SFR
- Value-add opportunities — renovate, raise rents, refinance
- Depreciation over 27.5 years; 1031 exchange eligible
- More complex — more tenants, more systems, more things to break
- Operating expenses run higher (38–45% for 5+ units)
- Commercial financing at 5+ units — shorter terms, balloons, DSCR constraints
- Harder to sell one unit; you're selling the whole building
Watch Out
- The 5-unit financing cliff: Cross from 4 to 5 units and everything changes. Conventional becomes scarce. You need DSCR and commercial underwriting. Plan the jump. Some investors stay at 2–4 units specifically to keep residential financing.
- Pro forma vs. actuals: Sellers show "stabilized" NOI with projected rents and low expense ratios. Verify. Pull rent rolls. Check actual property tax bills. Get insurance quotes. A $20,000 NOI error at 5% cap = $400,000 valuation error.
- Deferred maintenance: Older buildings have hidden capex. Roof, HVAC, plumbing, electrical. Budget 2–4% of value annually for replacements. A 20-year-old building will need a roof in the next 5 years. Model it.
- Management transition: If the seller self-managed, your numbers assume you will too — or that a PM can replicate their efficiency. Management at 6–8% changes the cash flow math. Run both scenarios.
Ask an Investor
The Takeaway
Multi-family is 2+ units — duplexes through apartment buildings. More units spread vacancy risk and often improve cash flow per dollar. Financing splits at 5 units: residential below, commercial above. The Small Multifamily guide walks through the 2–24 unit sweet spot. The Deal Analysis guide gives you the underwriting framework. Start small, verify the numbers, scale when the math works.