Duplex vs Triplex for House Hacking: Real Numbers, Real Tradeoffs

A multifamily property is any residential building containing two or more separate dwelling units under one roof — from a side-by-side duplex to a 300-unit apartment complex — where each unit has its own kitchen, bathroom, and entrance, and each unit generates independent rental income.

A lease is a legally binding contract between a landlord and a tenant that grants the tenant exclusive use of a property for a specified period in exchange for rent — establishing every right, obligation, and financial term that governs the rental relationship.

An offer is a formal written proposal from a buyer to a seller specifying the price, terms, and conditions under which the buyer is willing to purchase a property — and once the seller signs it, the offer becomes a binding purchase agreement.

Closing is the final step in a real estate transaction where ownership officially transfers from seller to buyer — documents are signed, funds are wired, the deed is recorded, and you walk away with the keys.

A lease renewal is a formal agreement between a landlord and tenant to continue the tenancy beyond the expiration of the original lease term — typically on updated terms, a new rent rate, or both. It differs from a month-to-month lease in that it resets the lease clock with a defined new term rather than rolling on a periodic basis.

A deduction is an expense the IRS lets you subtract from your taxable income before calculating what you owe. For rental property investors, deductions are the engine of tax strategy — they're how you legally show a "loss" on paper while collecting positive cash flow.

A spread is the numerical difference between two rates or yields — most commonly the gap between real estate cap rates and 10-year Treasury yields, or between mortgage rates and benchmark interest rates. Investors read spreads as a signal of whether real estate is attractively priced, fairly valued, or dangerously expensive relative to risk-free alternatives.

A pool is a swimming pool on a rental property — a double-edged amenity that can command $50–$150/month rent premium in warm climates but adds $150–$300/month in maintenance, 20–30% to landlord insurance premiums, and significant liability exposure, with net impact on returns varying by market and property type.

A driveway is the paved or gravel surface that connects a property's street frontage to its garage or designated parking area. For real estate investors, it is a functional asset that affects curb appeal, tenant satisfaction, liability exposure, and rehab costs.

A water heater is a mechanical appliance that heats cold water from the supply line and stores it in an insulated tank or heats it on demand, providing hot water to a property's fixtures and appliances.

Principal paydown is the reduction of your outstanding mortgage balance that occurs with each loan payment. Over time, as the loan amortizes, a growing portion of every payment chips away at the principal, building equity in the property.

A shared wall—also called a party wall or common wall—is a structural wall that separates two adjacent dwelling units in a duplex, townhome, row house, or other attached housing. Both property owners share responsibility for the wall, and its construction quality directly affects sound transmission, fire safety, and property value.

Turnover cost is the total expense when a tenant moves out and a new one moves in—lost rent during vacancy, repairs, cleaning, marketing, and leasing fees.

Break-even occupancy is the minimum occupancy rate at which a property's rental income covers all operating expenses and debt service—the point where you stop losing money and start breaking even.

PITI is your total monthly housing payment—principal, interest, property taxes, and homeowner's insurance. It's the number lenders use for the housing-expense-ratio and debt-to-income qualification.

A fourplex is a residential building containing four separate dwelling units—the maximum number of units that qualify for FHA owner-occupied financing when you live in one unit.

A triplex is a residential building containing three separate dwelling units—each with its own entrance, kitchen, and bathroom—typically under one roof.

A landlord is the owner of rental property who leases it to tenants—responsible for maintenance, rent collection, lease enforcement, and compliance with landlord-tenant laws.

Rental income is the money a property owner collects from tenants in exchange for occupying a residential or commercial property. It is the foundation of buy-and-hold real estate investing.

An asset is something you own that has economic value and can generate income or appreciation. In real estate, your properties are assets — the duplex, the single-family rental, the multi-family building. They sit on your balance sheet opposite your liabilities (the mortgage, the hard money loan).

Appreciation is the increase in a property's value over time — from market forces like inflation, population growth, and demand, or from investor action like renovations (which is forced appreciation).

A down payment is the initial cash you pay toward the purchase price of a home—the rest is financed with a mortgage. The size of your down payment affects your ltv, your monthly payment, and whether you pay pmi.

Owner occupancy means you live in the property as your primary residence — a requirement for FHA and VA loans that unlocks low down payments and better rates in exchange for actually moving in.

Liquidity is how fast you can turn an asset into cash without taking a big hit on price. Real estate is illiquid—it takes weeks or months to sell.

A duplex is a building with two separate residential units — each with its own entrance, kitchen, and living space — often used for owner-occupancy or as a small rental investment.

Replacing an existing loan with a new one—often to secure a lower interest rate, change terms, or extract equity.

A professional assessment of a property's fair market value, typically required by lenders before approving a loan.

A mortgage is a loan used to purchase real estate, with the property serving as collateral—if you stop paying, the lender can foreclose and sell the property to recover their money.

Leverage is using borrowed money to control a larger asset than you could afford with cash alone—and it amplifies both returns and risk.

Equity is the portion of a property's value you own outright—the property's value minus any loans secured against it.

House hacking is living in one unit of a multi-unit property (or renting rooms in a single-family) while tenants pay most or all of your mortgage — turning your housing cost into an investment.

An FHA loan is a government-insured mortgage that lets qualified borrowers buy 1–4 unit properties with as little as 3.5% down — as long as they live in one unit as their primary residence for at least 12 months.

Depreciation is the IRS allowance that lets you deduct a rental property's building cost (minus land) over 27.5 years — a non-cash expense that lowers taxable income even when the property appreciates.

Cash flow is what's left in your pocket after a rental pays all its expenses — including the mortgage. NOI minus debt service. What actually hits your bank account each month or year.

The percentage of time a rental property sits empty and produces no income, calculated as vacant units divided by total units — the silent profit killer in rental investing.