A fourplex can appeal to investors because of four-unit cash flow and higher operational coordination. Before committing capital, answer this question for the actual address: How does the deal perform when bookings disappoint? The method is to calculate monthly cash after debt, fixed costs, variable expenses and replacement reserve under base and downside revenue.
Make the decision before the deposit is at risk
Build monthly cash, not only an annual profit line. Debt and insurance continue during a weak booking month, while variable expenses fall with occupancy. The largest cumulative deficit determines reserve need. Stress correlated problems, such as a revenue dip during a repair, instead of changing one optimistic input at a time.
What changes for this property
Four rentable units do not automatically mean four STR permits or four independent revenue streams. Confirm parcel-level restrictions and whether the building's common areas can handle the guest pattern. Unit-level revenue and expenses are essential; a strong unit can conceal a weak one in an aggregate pro forma. Conventional multifamily economics offer a useful exit cross-check.
The revenue case should build unit-level forecasts before aggregating revenue. Record the source, the period covered and any owner-blocked nights beside the forecast.
The physical file should address fire separation, roof, parking, meters and capital backlog. The legal and insurance file should address parcel caps, lodging rules and resident access. A favorable answer on one does not repair an unsupported answer on the other. Obtain written, address-specific evidence before letting the contract's protection expire.
Documents to request
- Monthly revenue model, debt schedule, fixed bills and variable-cost quotes.
- Property-specific records for fire separation, roof, parking, meters and capital backlog.
- Written confirmation of parcel caps, lodging rules and resident access.
- Financing sensitivity: Loan eligibility can turn on occupancy and property condition.
Run the downside case
Worksheet: Monthly cash = revenue - variable expenses - fixed bills - debt payment - replacement reserve. Track the maximum cumulative deficit, not only year-end profit.
Cut occupancy, raise insurance and add one repair. Keep the original and stressed worksheets side by side. Recalculate cash needed at closing, the first twelve months of cash flow, and the reserve required to survive a delay or repair. If a source is missing, mark that input as unverified rather than filling it with the seller's optimistic estimate.
Operating exposure to price: Turnover density, noise and common-area care. Identify the vendor, fee, start date and backup for each required task. Those costs affect the underwriting and the date of the first rentable night.
Decision rule for the buyer
Require a reserve that covers the worst plausible cash-burn period. Also test the exit: conventional multifamily demand offers a possible fallback. A business owner should decide whether the property still fits when attention is focused on the primary business; a real estate investor should compare the same capital with the next available deal on a consistent after-reserve basis.
Use the existing BNB Accelerator guide for the broader method, then bring the address, documents and assumptions to a qualified lender, insurer, attorney, CPA or inspector as appropriate. These pages are decision worksheets, not a representation that any listed property type is available or approved in a given market.