Well, not visualized with pictures, whaddaya expect of me. But I had this
previous post about how parking minimums capped potential density, which got into algebra as I approximated infinitely tall and narrow towers to squeeze the most use out of a lot. I realized there's a much simpler way of figuring it out:
dingbats. Assuming one doesn't get into the expense of multi-level parking, the maximum parking you can get out of a lot is the entire lot, with your actual building on stilts above an open garage or stretch of carports. Or not open garage; point is, your whole first story is cars, and people go on top of that.
So then it's just a matter of what the legal ratios let you do with that parking. If you want 60 m2 2 BR apartments and the law says 1 30 m2 parking space per bedroom, then you have 1:1 apartment:parking space, and all you can get is one story of living space. Your development is two stories, kind of: a level of apartments above a ground level of parking.
If the law lets you have only 1 space, then it's 2:1, and you can have two stories of residences.
1 space per 90 m2 (about 1000 square feet), 3 stories.
2 spaces per 90, that's 90 m2 apartment : 60 m2 parking, so 1.5 stories of housing, awkward. Maybe you do a terrace with more balconies or skylights, or maybe you just build bigger apartments to use up the space.
1 space per 30, that'd be the same as 2 per 60, one story.
1 space per 15, that's 1:2, and you wouldn't even be able to use your whole second story, only half of it. One level of cars, half a level of apartments. Realistically you'd just have 1/3 of your lot be first story apartments, and the other 2/3 be parking. Even more realistically, you don't build 15 m2 apartments.
How about non-housing? Same idea: 3 spaces (330 square feet each) per 1000 square feet of office space is 1:1, so at most you could have one story of offices above a layer of parking. Office parks and malls are more likely to build multi-level parking though, as are big residential businesses; it's not worth the expense of ramps and such for small ones.
By contrast, of course, without parking the sky is almost literally the limit. 5 stories, 10, 20, 40, 80...
Also note that ubiquitous dingbats means that everything at ground level is a garage. Pretty yecchy. Avoid that, and density drops again.
Often people don't do dingbats, of course, they either do a single story next to parking, or a multi-story next to parking. But those will be even less dense than if the whole lot were used for parking.
Another way of looking at it is there's a physical limit to how many cars you can have anywhere with ground-level parking, and parking requirements tie the number of apartments or bedrooms, and thus of people, to the number of cars and parking spaces. Cars first, people second. So for developers it becomes a question not of "how many people will I build for" but "how much space will I provide the maximum number of people I can have?" If there's 1 parking space per bedroom then you can't build more bedrooms by building up, you can just choose how big the bedrooms and apartments are. One size at one story, twice as big at two stories -- but it's the same number of bedrooms.
A friend seemed skeptical of "parking requirements make housing cost more". He didn't give his argument apart from seeming to think landlords will charge as much as you can pay (as opposed to supply and demand), but I came up with a counter-argument anyway. All else being equal, bigger apartments cost more than smaller ones, right? So consider a 60 m2 apartment with attached parking space. In a sense, this is like a 90 m2 apartment. Not exactly like, since the parking lacks power or quite likely even walls, but in area it's 90 m2. In cost it will be between a 60 and 90 m2 apartment without parking space; if land is expensive, dwarfing pure building costs, it'll probably be much closer to 90.
So when you rent a 60 m2 apartment with parking space, you're kind of really renting a 90 m2 apartment,
whether or not you use the parking space. If you don't use it you're stuck paying up to 50% more rent anyway for something you can't use.
If there are two spaces, then you're virtually renting a 120 m2 apartment, twice as big as the actual apartment you live in.
If there's 1 space for a 30 m2 apartment, you're renting 60 m2.
If there's 1 space for a 15 m2 microapartment, then you're renting 45 m2. Again, for such small housing, parking is 2x as big as the human space, and no one's going to do this, meaning that such limits de facto ban such housing from existing.
More bluntly, if parking is required, then it is impossible to build an 'apartment' less than 30 m2, counting the parking. And that wouldn't even be an apartment, just a parking space. 45 m2 is the real limit. If someone desperate to not be homeless wants to just pay for 15 m2, too bad. The city won't let them.
In this case multi-level parking doesn't change matters, it just allows more apartments to be built. You're still stuck paying for an apartment+parking that's bigger and more expensive than you might want.
How much more in reality? Varies a lot. Alan Dunning
says land in his part of Seattle costs $38-45 per square foot, which is up to almost $15,000 for a parking space. Shoup found UCLA was building garages at $15,000-30,000 per space, not counting land costs. Beverly Hills developers were willing to pay $53,000 to get out of providing parking.
Even at the low end, an extra $15,000 on a $200,000 condo or home is an extra 7.5%. Not huge compared to 50% or 100% but not trivial. People would sure kick if the government levied a new 7.5% tax on all housing sales. $15,000 on a $100,000 condo would be 15%.
Parking requirements both limit the supply, by limiting density, and create a minimum size of practical apartment to build and rent, and a pressure to build bigger housing where the parking add-on isn't so proportionally big.
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