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Comment by mlyle | Hacker News Reader

> This is necessary because many office floorplans are huge with modern HVAC and when converted into residential you end up with either undesirable or illegal apartments due to lack of windows/egress/etc.

Couldn't you just wall off the middle? I mean, you do get another set of windows on the inner courtyard, but it seems expensive to perform such major surgery on a building.

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If you don't use the center of the building, then you only have room for one "ring" of residential units, whose windows face the exterior of the building. If you cut a donut hole down the center of the building, now you have room for two rings of units. Furthermore, in places like NYC, developers are allowed to "bank" the floorspace that comprised the donut hole and add new construction on top of the building so that overall square footage remains the same.

They have limits on building square footage but not height? Or is that a weird loophole in a height restriction?

I think there are limits on both. Floor area ratio (https://en.wikipedia.org/wiki/Floor_area_ratio) is how it is coded into regulations. The lot size and the height restrictions create a bounding box that the building needs to fit within.

Common in NYC to do that to say you have the tallest building by height even if you were only approved to build X floors (your service floors don’t count) — from the couple videos I’ve watched about it over the years (see 432 Park Ave).

> Furthermore, in places like NYC, developers are allowed to "bank" the floorspace that comprised the donut hole and add new construction on top of the building so that overall square footage remains the same.

Oh, yah, that's cool. You probably have a lot of systems surrounding the building (and ingress/egress) designed for that total volume.

Depending on local laws.. windowless apartments are illegal. windowless bedrooms are illegal. etc.

I think they’re suggesting just having dead space in the middle.

Because that would convert space really badly. If you're making 10'x10' rooms out of a 100'x100' space, it's 74% dead space. If a floor is more than 10,000 sq feet, maybe 40,000 sq feet, it goes up to to 90%.

I mean, numbers are made up, but the point holds.

I’d be interested to see people get really creative with it. Throw a gym in on one floor. Cinema room on another. Storage units in a few more. Probably difficult to structurally support a pool on a floor not already designed for one but sure, let’s throw one in there too. A kids playroom is maybe a little depressing with no natural light but it could work. Hell: keep the middle commercial space and put a grocery store in.

Obviously once you’re talking about true high rises you’re going to run out of possibilities and I know the maths is still very rough. But it’s an interesting thought exercise to think about just how many amenities you could pack into a building.

Sound like what inevitably happens to my Sims games, just start filling in those gaps

Dance floor #3? Make it happen!

Funnily this is kind of possible. Tokyo has at least one dance club located in a residential high-rise, just padded enough that the sound doesn't carry into the apartments around it. It's been a while though and I can't find the name now - please post a link if anyone remembers where it was.

Liquid room?

20 Exchange in NYC is like that. Each chunk of floors gets a nearby amenities pod, with singletons for the really expensive stuff. Still, I think you’d have to get a screaming deal on the building in order to be able to make that economical.

Another use for interior rooms could be meeting/ conference rooms/ teleconference/ coworking spaces. Some premium apartment landlords currently have these in their clubhouses, usually reservable by the hour, residents usually get so many free credits a month.

Is this a thing, in planned conversions? If the pricing varied by day and time, or was dynamic, it could work very well. With secure lockers adjacent. (Would that require mixed-use zoning?)

A teleconference room (/remote classroom) by day could be time-multiplexed into a cinema room off-peak (with some compromise in seating plans), leasing company just needs to handle cleaning deposits and video surveillance at start and end to check users keep it clean.

I know your numbers are made up but presumably an apartment is much deeper than 10'. You'd want to make it as narrow and deep as practical. 20x45'? 25x36'?

I get that you get (almost) twice as many apartments (presuming you don't build up higher), but you also get a massive and complicated one time cost. It surprises me that it could ever be worth it.

I call this the Chicago layout -many apartments are long and narrow. I have assumed it was to ensure access to two fire escapes. To hazard a guess, I have seen some that might only be 15’ wide, supporting a 10x10 room with a hallway to access it.

Chicago lots are long and narrow. Typical Chicago residential lot is 25x100 or so. Street in front, alley in the back, garage if you have one is a separate building fronting the alley. Many houses are built as "two flats" or "three flats" i.e. two or three houses stacked on top of each other.

I was a bit surprised by this, but, yea, pulled up random part of chicago and it's basically exasctly as described.

https://www.google.com/maps/place/Chicago,+IL/@41.7332309,-8...

This is really common in and around Boston too. The architectural style is from the area and we cal them three deckers (in Boston) or triple deckers (everywhere else). Lot size is probably similar, and they’re still highly valued (if kept up) to this day because of their construction and other benefits. I live in one now and others around me go for 750k+

https://www.dotnews.com/columns/2014/glorious-three-decker

You could make the rooms bigger. Also surely they aren’t always squares which is the worst case.

Why not make storage spaces?

It's legal, in most cases, to omit an egress window in bedrooms in high-rise buildings—but only because the building includes fire-safety features (for example, sprinklers, fire alarm systems, and egress stairways)

https://www.greenbuildingadvisor.com/article/bedrooms-withou...

Two different rules

Bedrooms have egress requirements

Apartments have window requirements (eg natural light)

Nah a whole bunch of jurisdictions made it so that with appropriate firewalls and other features there need be zero egress aside from the singular entrance/exit door.

Windows can be unopenable etc.,

It's literally because of hi rises and the issues with it being pointless to jump from 10+ stories (you'll also suffer less, as the smoke will make you pass out long before you're actually being burned).

Yes, both rules vary by jurisdiction. I was just saying many places have both.

No it is not legal in NYC.

There's been a whole discussion of the code though as modern mid/high rises have - concrete, "fireproof" (in terms of adjacent unit to unit) construction - sprinkler systems - internal hallway leading to 2 stairways

All of which are lacking in wood frame homes which make up a higher amount of home fire deaths. So there has been an argument that you could build housing much cheaper if you could rely on the concrete & sprinklers, and could lighten the rules around multiple stairs / windows / etc.

An interesting debate, with of course, tradeoffs.

Donuted buildings will forever remind me of the Ponte Tower building.

(1) https://www.theatlantic.com/entertainment/archive/2017/02/th...

The South African Building That Came to Symbolize the Apocalypse

https://archive.today/qfZ91

Well, we're calling them "donut holes", but they're actually rectangles. :P

Don't be such a square!

In Hong Kong, pre-handover, I stayed in a windowless hotel room.

Those still exist in Hong Kong today. And many other places in the world, for that matter. Even apartments without windows aren't that uncommon. In subdivided floors they're cheaper than the street facing ones, but some people prefer them anyway because there is less noise from the road.

I love to sleep in darkness. Stayed at an Airbnb with a windowless bedroom. Best sleep I ever had.

Second, would pay extra for that

Have you guys tried blackout curtains?

I stayed in one in london last year. It was great until noisy people came back at 2am

2 great sleep killers: light and noise. "Windowless" only fixes one.

But you effectively get another set of apartments that have interior windows. Sure they’re not gonna have a great view but they’re still rentable apartments

Depending on what you do with the interior, they can actually be great apartments. Much quieter than street facing, put a nice little courtyard in the center.. etc.

It definitely needs to be designed properly.

I once worked in an office where all the windows face a plain interior courtyard. It was terrible as nothing ever moved and you could only see the ground, more windows, and the sky.

Many apartments in Europe are designed this way. The interior courtyard in most of them just contains trash cans and residents' bicycles or mopeds. They're not especially interesting views. But people don't generally move to cities for exciting views out their window, the other benefits outweigh it.

I would have thought it would make perfect storage space.

turn it into storage space I'd say

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