Two-unit at 315k or three-unit at 430k? My down payment stretches one way.

Put both on the same expense assumptions and the comparison gets easier. Right now you are giving the duplex a real insurance number and the triplex a rumor, and you are giving the triplex no utility line at all.

Try it this way. Duplex: 34,200 gross, taxes 4,100, insurance 1,900, management at 8 percent if you ever stop self-managing is 2,736, maintenance and capex at 1,200 per unit is 2,400, vacancy at 5 percent is 1,710. That lands you near 21,300 net.

Triplex: 36,900 gross, taxes 5,600, insurance call it 3,400 until proven otherwise, management 2,952, maintenance and capex 1,200 per unit is 3,600, vacancy 5 percent is 1,845, plus heat and water for the whole building which in a cold market on an old boiler could be 5,500 to 7,000. That lands you somewhere near 13,000 to 14,500.

So the triplex is more gross rent and less net income on those assumptions, and it costs 115k more. The whole thing turns on two inputs: the real utility cost and whether the rents are under market. If heat and water come in at 4,000 and market rent is 1,300 a unit, the triplex is the better asset by a wide margin. If heat and water are 7,000 and 1,050 is genuinely market, it is not close.

Get the bills. Do not model this off a listing sheet.

The structural reason people step from single family into two to four units is that these properties still qualify for residential financing rather than the commercial loans required at five units and above. That means lower down payments and generally more favorable terms on a building that produces several rents. Confirm the specific program, down payment and reserve requirement in writing with your lender, because those terms differ by program and change over time.

On the choice in front of you, the number that matters is net operating income per dollar of price, and the utility structure is what separates your two candidates. A separately metered duplex pushes heat and water onto tenants. A master-metered triplex puts both on you, which converts a variable cost you do not control into your own line item. In a cold market that line can swing several thousand dollars year to year, and the swing lands entirely on your cash flow.

Small multifamily cap rates have generally run modestly above single family, roughly 6.0 to 7.2 percent, and that premium exists partly because of exactly this kind of operating complexity. The vacancy advantage is real, though. Losing one tenant in a triplex costs you a third of the income rather than all of it, and that resilience is a large part of why the sector has been comparatively stable.

The answer depends on one assumption: whether those triplex rents are at market. If they are, you are paying 115k for a unit that nets less after utilities. If they are 20 percent under market, you are buying the spread and the older systems are the price of it. Two years of utility bills and three comparable rent listings settle it.

Reading this from the loan side rather than the ownership side. Three and four unit properties are often underwritten a bit differently from two units even inside the same residential category, and some programs have applied extra tests or higher reserve requirements at three units and up. I am not going to state the current rules because they move and they vary by lender and program, so ask your loan officer for the term sheet and the reserve requirement in writing before Thursday.

The other document worth asking about is the appraisal type. Two to four unit appraisals usually include a rent schedule, and the appraiser's opinion of market rent for each unit is a free second read on whether those 1,050 rents are stale. If the appraiser comes back at 1,300 you have your answer without arguing with the listing agent about it.

One more thing on the owner-occupied path. If you move into a unit you take a rent off the top, so the triplex stops being a three-income building for as long as you live there. Model the year you live there and the year after separately, because they look nothing alike.

I will be the person arguing for the dull answer. The duplex has separate meters, a newer roof, a real insurance number and rents that already look like market. You can hold that building through a soft year and a broken furnace without a spreadsheet.

The triplex has three unknowns you have not priced and one of them is a boiler. First buildings teach you what you did not know to ask, and I would rather learn that on a property where a mistake costs 3,000 than one where it costs 15,000. The third unit will still be for sale in some form in two years, and by then you will know your own market's turnover cost from the inside.

Sextant's numbers are the part I would sit with. More gross rent and less net income is the trap in this size of building, and it catches people who compare price to rent and stop there.

Ask what the boiler is and what year. A 40 year old cast iron unit serving three apartments is a 12k check waiting.