My partner and I are both voracious students of cities, and we care deeply about all of this stuff. Even though St. Louis, Missouri isn’t exactly hurting for vacant affordable apartments begging to be put back into productive use—the city was built for a million people, and is currently home to just over 318,000—that’s not true in every neighborhood, and the crowded ones where most Airbnbs pop up are also the ones closest to grocery stores and decent public schools. Even in our still-establishing neighborhood of Fox Park, we’d both frowned whenever we saw a triplex owner installing the telltale keypad locks on every single door and moving truckloads of IKEA furnishings into empty living rooms. Sure, Fox Park has its share of affordable vacancies, but ask around, and you’ll find that many of them are owned by slumlords who are extracting the last bit of wealth they can get out of their tenants as their buildings rapidly decline. Any real student of cities knows that the difference between a city with a wealth of affordable housing and a city with a wealth of well-managed, non-exploitative affordable housing is a vast one.

So why, we wondered, would anyone with a conscience subtract a unit from the neighborhood housing stock that could be managed by an ethical property manager and become a home to a family in need? Why would anyone subtract a neighbor in favor of a crasher?

What happens when you outgrow your house?

Then…life happened.

For a while, my partner and I stuck to our guns. We moved into the tiny, 80’s chic one-bedroom unit at the back of our duplex, and rented out the much nicer two-bedroom in the front to a group of students. We grit our teeth and lived with the many repairs our unit needed, incrementally developing as we slogged along. The tenants’ apartment was in great shape, and their rent almost covered the whole mortgage, so we sunk nearly every penny we’d previously put towards rent towards replacing the hideous, mold-infested carpet with hardwood floors, replacing the oversized AC unit that made our duct system sweat brown water through our ceilings with one that actually fit.

(Okay: we spent more than we’d spent on our last apartment’s rent on this stuff, but with the huge offset of the tenant’s rent, it was manageable.)

For a while, things were looking good, and we even managed to save up enough for a seriously great deal on a four-family in a developing neighborhood where we could offer even cheaper rent to lower income tenants.

And then….life kept happening.

First: the four-family cost way more than we thought, and the unforeseen expenses came at us from bizarre angles. A “free” city lead remediation program that paid to replace the building’s old, drafty and—oh yeah—poisonous windows ended up costing us thousands when the city wouldn’t re-hang the blinds, or re-seat the door thresholds, or anything not on their bureaucratically-stamped work order. Tenants struggled to make rent or suddenly needed to move, and our pro forma vacancy budget was way off. A water heater broke. Then another one. In under a year, it looked like we’d have to switch out a third, none of which were anticipated on the inspection. We were committed to keeping the rents low, but we were starting to understand, first-hand, why it’s so damn hard to keep housing affordable, even in a cheap building with no frills.

And not all of our life-happenings were financial. Simply put, we were outgrowing our tiny little back-of-the-duplex apartment. As a 28-year-old first-time home buyer, I was thrilled to have a couch I could offer to friends who needed to crash on cross-country drives; as 32-year-old, I really wanted to be able to offer them a bed. I wanted to have dinner parties instead of meeting friends at bars, and our micro-living room had space for a café table and no more. Also, I’d gotten this weird, wonderful work-from-home job for a little non-profit in Minnesota—it’s called Strong Towns, have you heard of it?—and having no place to set up a laptop besides that café table, my bed and my couch was getting old.

And one member of our family was literally outgrowing our space.