Square footage is so broken and weird
It's all vibes
It’s been a while since I wrote about peculiar ways things are measured. If you have an interesting/wonky measurement or unit from some niche in the world that you’d like me to look into and try to write something about in the future, let me know.
Decades ago, back when I was in high school, I took a summer job with a family friend who was a real estate agent in NYC. The job was a simple one, I was an “apartment shower”. As a teenager that obviously did not have a real estate agent’s license, my only job was to be take clients from the office to the list of apartments that potential renters wanted to see and let them in using the provided keys. Since I wasn’t licensed, I couldn’t really say anything about the apartment other than off whatever facts were on the listing sheet, I was merely a courier of keys and people. The clients would work with the agent at the office to build up a list they’d like to see that day, and then I’d take that list and head out with the clients to the subway or taxi to see the 3-5 apartments for the day.
It was a great way to see a lot of apartments in the city at the time — from the infamous 4th floor walkups with the creaking narrow stairs, to tiny studios in buildings with ancient tiny elevators, to the occasional luxury 3-bedroom in brand new towers. As far as I know, the laws have changed in NYC and now everyone involved in handling real estate in this way is now required to have a license, so that summer job doesn’t exist anymore.
One memorable thing that came up quite often during that summer of apartments was how people would often ask about the square footage of the apartment — and I would more often than not be unable to answer them. Unless the apartment was brand new and had accurate floorplans in the listing, the value wasn’t really known or advertised.
This is because the NYC housing market works more off vibes than square footage. More specifically, apartments are typically classified by the number of bedrooms that they have. The price of rent was largely based around a few primary factors — the location, the number of bedrooms, and the luxury level of the building. The overall size of the apartment acts as a kind of fudge factor where especially spacious apartments could command more rent, but the relationship is sorta hand-wavey since the buildings dated from the 1920s into the 2000s and designs varied wildly over the years.
Roughly back in the early late 90s, early 2000s, there’d be a base rate of rent for a typical studio or 1-bedroom in an area, say $800/month for a run-down studio meant for students in the East Village. Then, every extra bedroom on top of that would usually be an extra $1000/mo on top. The whole system “works” because there are legal minimum rules for the size of a bedroom — 80sqft and two forms of egress, a door and typically a window. Since landlords are profit-maximizing, if they had a space that could be subdivided into two bedrooms, they would have done so.
A curious artifact of NYC’s housing is you’ll see the mention of “flex” apartments, listed like “1BR, flex 2BR”. It means that there’s supposed to be enough space in a bedroom where a temporary wall could be added to create a second bedroom. There’s companies with specialized partition walls that tension against the floor and ceiling to serve this market. It’s a “innovation” for the many people who can only afford the massive rents with the help of a roommate.
An industry of ~vibes~
As you would expect, people who aren’t from the city are very confused at the arcane setup we have here. Some people, especially those from other countries, are shocked to know that I had no idea what the livable area of an apartment is. I honestly have no mental model of how much living space I have/require. There are just “large bedrooms” and “small bedrooms”. I’ve lived in places where you can mostly fit a bed, desk, and chair in the bedroom, as well as significantly more comfortable spaces. I have no idea what the area of those rooms are.
But while the situation in NYC probably represents a pretty extreme case of chaos, much of the real estate industry operates on various levels of vibes.
Perhaps the most mind-boggling metric in the industry is the “square footage” measurement of living spaces here that is quoted in records and advertisements. As far as I’m concerned, the number is often a vague lie. The problem is compounded by the fact that I don’t know exactly which of the many different ways to measure and report the measure was actually used.
As a data person, you’d think I’d be obsessed about this number because price per square foot is a pretty critical metric, especially for commercial real estate. But I’ve largely stopped worrying about it in residential settings and am mostly making judgements based on vibes now. Any place I see, I have to ask people “did you include the garage/basement/enclosed porch space in the footage?” because the answer differs every single time.
Sometimes people cite the square footage of a building as recorded in the local government department of buildings. It feels very official since the number from the government on scan of an official looking piece of paper. But the rules governing how those are measured vary wildly. Some places don’t count finished living spaces that are below ground. Some only count if a certain amount of the wall is exposed above ground. Some count everything.
Rules can also differ as to how high a ceiling needs to be before space “counts” — and what about rooms with slanted ceilings like finished attics? Plus, the government records can be decades old and the conventions for what counts may have changed. People could have also made plenty of unregistered/illegal/hidden modifications over the course of 100 years and lax oversight.
Well, if the government records are a bit dodgy, then another way is to measure the outside perimeter of a house or reading off a detailed survey. That will definitely give you the maximum area of the space contained within. Except you’ll be counting any unlivable space, like the actual thickness of the walls and unfinished spaces inside. You’d also overcount open multi-floor spaces like large foyers that extend up and aren’t real usable space for all the floors.
Other times, people measure the areas of all the major living spaces, the rooms and hallways, and then add it up to come up with a number. that works well for the big rooms, but if there are weird nooks and bends, things can get overlooked. I have this small triangle shaped closet between two rooms and no one can make me care enough to bother measuring its area. Plus, you’re measuring from the inside of the walls now, and the dimensions are going to be somewhat off compared to the outside perimeter. Oh, and how do you treat things like stairs?
Finally, there’s just plain old human error. The people who are doing these measurements could be practically anyone. A homeowner who’s only roughly measuring things with measuring tape, a realtor who’s incentivized to round up a little bit to make things look nicer, an appraiser who might spend two minutes in any given room but use a laser ruler. Any of these people will have different standards, tools, and techniques for measuring. They can even make data entry errors while putting the numbers into whatever system they’re reporting to (which aren’t standardized either).
Someone oughta make a standard!
You’d think that, given this complete chaos and sheer amounts of money involved, someone would have standardized the whole process by now.
And, you’re sorta right. The Federal National Mortgage Association, a.k.a. Fannie Mae, one of the biggest purchasers of mortgages from lenders, announced that in April 1, 2022, they were requiring that appraisers measure single family homes in accordance to the ANSI 765-2021 standard. Since they command such a large part of the mortgage securities market and banks really want to sell loans to FNMA to recover cash to make more loans, that’ll force appraisers to use those guidelines. But that doesn’t guarantee that the new measurements make it into any other data system about buildings.
As is typical of ANSI and ISO standards, which completely pisses me off, the standard text is copyrighted and you need to purchase it for $25. The closest free copy I found was a 2020 draft proposal, “ANSI Z765-2020: Square Footage – Method for Calculating”. The text provides a pretty detailed methodology for measuring the square footage for a single family home. The footage is supposed to be measured to the exterior of the walls. I’m not sure how they go about that exactly. The area for stairs count towards the floor they’re descending from. Plus there’s all sorts of guidelines for disclosing whether things are above/below grade (ground level), what’s considered finished or not.
But guess what! The standard only applies to single family homes. For anything else, the guidelines seems to be to measure interior dimensions out to exterior walls and sum it all up? Considering most houses in NYC are of the multi-family nature, I expect things will continue to be a mess.
But surely the free market would….
You’d think with so much money flowing around in the world of real estate, that some group somewhere would have attempted to overcome the patchwork nature of property data records. There’s big players like Redfin and Zillow now who make tons of money off of data surrounding property transactions. They are most definitely spending huge amounts of money ingesting data from government records and other sources with tons of custom code to handle quirks. You’d think that they’d want to push for better data collection for the benefit of everyone including themselves.
But instead, the first move towards a standard only started last year, and it still sorta boils down to vibes. I suppose since all this data collection is done on a bottom-up level (there’s no one centralized MLS database, but many privately run regional ones), there’s just no hope of getting everyone to agree to update their systems and processes.
We’ll have to see whether the new appraisal rules will have some kind of effect on the data going forward.
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I’m Randy Au, Quantitative UX researcher, former data analyst, and general-purpose data and tech nerd. Counting Stuff is a weekly newsletter about the less-than-sexy aspects of data science, UX research and tech. With some excursions into other fun topics.
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