A skyscraper city is on the horizon, but is its full potential being realized?

Seattle’s building boom is in full swing, and a healthy part of this is in new skyscraper construction. Over 37 projects are soon to come online adding more residential units, office space, and services to the Downtown, Belltown, Denny Triangle, South Lake Union, and First Hill neighborhoods. A few things stand out in a brilliant infographic by Nathaniel Williams:

1. Most of the new skyscraper construction is taking place in the Denny Triangle and South Lake Union;
2. A significant number of structures hover around two heights: ~440 feet and ~530 feet;
3. The list is missing this proposal, which could end up being the tallest building in Seattle;
4. 28 projects will provide residential units, all but 3 will have retail uses, and 13 will deliver office space*;
5. The Amazon towers propose very high parking ratios when compared to similar projects; and
6. A supermajority of the hotel rooms proposed will be located in the Denny Triangle.

The big outlier

The level of Seattle’s skyscraper boom north of the Downtown Core seems quite remarkable all things considered. But, the most striking trend seen in the infographic above is just how many projects are capping out at particular heights. Once you get above the threshold for low-rise structures, one would reasonably presume that skyscraper structures with the same or similar number of floors would consist of somewhat varying heights when capping out. Or, that’s what we have come to expect with skyscrapers, particularly with the tallest amongst us.

There’s a lot that can drive the average floor height of a skyscraper: what market the skyscraper is intended to serve and the mix of uses that the skyscraper is created to provide for (office, retail, parking, and residential) for instance. Most skyscrapers range from 10 feet to 13 feet for average floor height. However, skyscrapers in the low-rise and mid-rise ranges are very consistent in the number of stories, average floor height, and their absolute height.

What’s happening here with skyscraper heights and total number of floors isn’t accidental. A pro forma has been established which is presumably driven by the city’s land use regulations on floor area ratio and building heights. In other words, land use regulations are holding these structures back from going even higher than they are. With less restrictive zoning, projects proposed for taller skyscrapers would likely still pencil out. And by extension, this would have the benefit of translating into more efficient use of a limited urban land supply designated for density while potentially lowering costs for future occupants.

*Based upon projects with complete information.