There’s also a limit on how high up in the air you can put combustible (i.e. wood) construction. No combustible construction is allowed above the reach of fire department ladders plus hose spray, for instance.

Finally, wood structures taller than five stories experience significant problems due to differential shrinkage of wood plates over time, so the practical limit on wood buildings is five stories even though they could probably go higher than that and still be structurally sound.

So, that’s why you see a lot of 5 plus 1 wood over concrete buildings. They’re very cost-efficient within the boundaries of their limitations.

If you want buildings to be taller than 65 feet, you’ve got to allow them to get tall enough that the economics of steel and wood construction make them “pencil out.” That means at least 105 feet, and preferably 120 feet or more. It’s a quantum jump, rather than an incremental rise along a continuum.

Kate G@13: I think the (non-boulevard) streets of Paris do tend to be narrower than Seattle’s, but aren’t most Parisian buildings designed around an central courtyard? I have the impression that a Parisian apartment’s lot coverage is much less than a comparable Seattle building.

More broadly, I think there’s a danger of the “density” and “height” arguments getting conflated. They are not one and the same, and can be mutually defeating if groups like this SLU group are successful in using their 400 ft scare tactics to throw people off of density in general. The key here, it seems, is to make the argument for a diversity of building types – it’s about the package of livability, not just the skinny tower.

One thing that seems to be missing from most discussions of height limits in denser zones is the “dead zone” between 65 and 105-120 feet. At 65 feet and below, it is practical to use wood frame over concrete plinth construction (5 floors of wood over one concrete level). Above 65 feet, you’ve got to upgrade the structure to steel or concrete all the way up. That typically doesn’t work economically until you get up above 8 to 10 stories. So, zones with 85-foot height limits usually wind up being underbuilt, or filled with buildings that are unaffordable and/or vanity projects.

But that’s not the important thing; rather, Parisian parkland largely works as open space because it is readily accessible and the two large edge parks are VERY large. Bigger than Central Park or Hyde Park (and there are two of them!) and designed in the English style – thankfully.