Moving from a duplex to a single house, what actually changes in the operating numbers?

Question

I run small multifamily and every unit has taught me something, mostly about shared systems. Now I'm looking at a detached house for the first time and I want to know which of my operating assumptions I have to throw out.

My duplex assumptions: one roof over two rents, one lawn contract, two water heaters in one basement, a single trip covers two units. Vacancy on one unit still leaves half the income coming in.

On a house, every one of those flips. What I can't tell is whether the offsetting advantages are real or just talked about. People say single family tenants stay longer and treat the place better. Is that measurable or is it folklore? And does the yard actually cost what I think it costs?

Rena Guide · Accepted Answer

The tenure difference is real and it's the main operating advantage. Single-family tenants tend to stay longer than apartment tenants, often several years rather than one or two, because families with kids in a school district move less. Longer tenure means fewer turns, and the turn is the expensive event, so your annual expense line can come out better than your worse-per-unit economics would suggest.

What you lose is exactly what you listed. One vacancy is 100 percent of the income on that property, not 50 percent. That changes how much reserve you need per property, and it's why a single house wants six months of full carrying cost behind it rather than the thinner reserve a duplex can survive on.

On the yard, budget it as a real line. A basic mow-and-trim contract commonly runs $30 to $60 a visit in season, so a few hundred to a thousand dollars a year depending on lot size and climate. You can write the lease to make yard care the tenant's responsibility, and many single-family leases do, but enforcement is uneven and a neglected yard is a code citation in some municipalities and a slow decline in the property in all of them. A lot of owners keep the mowing in-house and price it into rent.

The number that genuinely changes on you is capital reserve. Your duplex spread the roof across two rents. On a house, the roof, the HVAC, the water heater, and the exterior paint all sit against one rent stream. Set that reserve in dollars off replacement cost rather than as a percentage of rent, because a percentage of rent will leave you under-reserved on a lower-rent house without your noticing.

One more thing to check before you're under contract: whether the house sits in an HOA. HOAs can cap rentals, impose a waiting period after purchase, or require tenant approval, and those rules vary by association and by state. Read the covenants, not the listing.

priya_n21 · Answer

The vacancy point is what stopped me from buying one house instead of a small building. One house empty is zero dollars that month and the mortgage is still due. Two houses at least averages out a little.

tylerbrooks9 · Answer

@marlow it averages out less than it feels like it does when the two houses are in the same submarket and the same job market. Two houses in one town go vacant for the same reason at the same time. The duplex at least gives you one roof and one insurance policy to manage, which is the part of this I actually care about, less stuff to keep track of per dollar of rent.

@cairn on the tenant care question, I'd separate tenure from condition. Longer stays mean fewer turns but also mean deferred wear you don't see for four years, and then the turn is a big one because carpet and paint are both at end of life at once. The savings are real, they just arrive lumpy.

Moving from a duplex to a single house, what actually changes in the operating numbers?

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