seattle's other problem is we allow way too much FAR and so for most projects in order to come anywhere close to maximizing it - it effectively requires much larger buildings with more units and a double loaded corridor.
FAR is floor area ratio, meaning the ratio of floorspace to lot size. Higher FAR allows developers to pack more units in which may encourage development but the way that they do that with the double loaded corridors makes for units w bad layouts and little natural ventilation and light.
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https://www.mercatus.org/research/policy-briefs/seattle-special-us-citys-unique-approach-small-infill-lots