[quickthrowman]

The reason five over ones are popular in the US has nothing to do with staircase requirements. The reason is money, like always.

You can stick build residential buildings up to five stories and it’s way, way cheaper than reinforced concrete and steel. They are mega complexes because the financial stakeholders want to maximize the available land and rents.

[ketzo]

“maximize the available land”

Part of the author’s point is that single-stair buildings can be built economically on much smaller pieces of land. This increases the number of plots — especially in urban environments — on which you can build MFH, plots which developers today wouldn’t even think of.

Legalizing single-stair buildings would not really change the viability of big apartment complexes, you’re right. But it would allow for smaller ones.

[Pxtl]

Yes. Especially since a big problem for Western cities is not "how do I build new megalopoli" but "how do I fill in density without acquiring a whole city block of houses in one go". For a single-stair walk-up you don't need a massive amount of property, you can plonk a pretty danged nice mid-rise building on the same acreage as one large detached house.

[ajmurmann]

With a single stair you can also get windows in opposite ends of the building for the same unit which makes a huge quality of life difference. Getting a real cross-breeze!

[Tiktaalik]

> The reason five over ones are popular in the US has nothing to do with staircase requirements. The reason is money, like always.

Yes it is money. More staircases remarkably increase the costs of buildings. Single stairway, cheaper buildings, more profitable to do other sorts of buildings, more variety of buildings etc.

(see also no parking mandates)

[bluGill]

Stairs are not expensivei they take space, but are cheay otherwise

[bell-cot]

By the time you've complied with all current codes, stairs themselves do take up an unreasonable amount of floor space.

But there's a usually-worse cost to the second set of stairs, that I'll call "geometry". A second set of stairs is not a giant support column, which you can wall off and ignore. The halls, doors, and such that it requires also suck up space, and impose many more restrictions on the layout of the actual living spaces for human beings - which are the sole reason for the building to exist.

[eru]

Space ain't free.

[FinnKuhn]

In most cities space is the expensive thing

[ethagknight]

At least in larger construction, it's the pathway to the secondary stair that takes up an exorbitant amount of space, hamstrings the layout. Also, code compliant fire egress stairwells are surprisingly expensive to build, costs more than the unit cost of a living space.

[closeparen]

It’s true that five stories is an economic sweet spot, but the idea is we could get five story point access blocks instead of double loaded corridor layouts.