sfrcalc.comHouse Hacking 101
House hacking means buying a property with more than one unit — commonly a duplex, triplex, or fourplex — living in one unit yourself, and renting out the rest. The appeal is straightforward: rental income from the other units offsets some or all of your own housing cost, and because you're buying as an owner-occupant, you often qualify for financing that wouldn't be available on a pure investment purchase.
Why the financing is different
Owner-occupant loans — including low-down-payment options meant for primary residences — are generally available on properties up to four units, as long as you actually live in one of them. That's a meaningfully lower barrier to entry than a conventional investment property loan, which typically requires a larger down payment. This is the mechanism that makes house hacking accessible to people who couldn't otherwise afford to buy a multi-unit investment property outright.
What "your net housing cost" actually means
The number that matters isn't the mortgage payment — it's the mortgage payment plus your share of operating costs, minus the rent collected from the other units. That net figure is what living there actually costs you every month, and it can land anywhere from a deep discount versus renting elsewhere, to fully covered, to (in a strong enough setup) the property paying you to live there.
| Total PITI (all three units combined) | $2,850 |
| Rent collected — other two units, net of vacancy | $2,280 |
| Maintenance & CapEx on rented units | $228 |
| Your net housing cost | $798 |
| Comparable market rent for your unit alone | $1,500 |
| Monthly savings vs. renting elsewhere | $702 |
The part people skip: what happens after you move out
House hacking is often a stepping stone, not a permanent living situation. Once you move out — to buy a single-family home, hack another property, or just want your own space — the unit you occupied gets rented at market rate too, and the property becomes a standard rental. That's worth modeling upfront: a property that looks mediocre as a fully-rented investment but excellent as an owner-occupied house hack is a different bet than one that works well either way. Run both scenarios before you buy, not just the one you're living in now.
What's easy to underestimate
- Being a landlord to your neighbors. Maintenance requests, noise complaints, and rent collection are happening in the building you sleep in, not at arm's length.
- Shared systems and deferred maintenance. Older multi-unit properties often have shared roofs, HVAC, or plumbing where one large repair affects every unit at once — budget CapEx reserves accordingly.
- PMI or mortgage insurance on a low-down-payment owner-occupant loan, which adds a real monthly cost that's easy to leave out of a quick mental calculation.