[dragonwriter]

> A good example is to allow each building to only double the square footage of the median building within, say, a quarter-mile radius of the property being redeveloped. This means that SFH's can only become duplexes until duplexes are the norm.

No, it doesn't; existing SFHs can, and have when allowed to, become duplexes, triplexes, and sometimes even quadruplexes without changing square footage at all, with doubling, you can go even further. All it takes is remodeling so that each subdivided unit meets minimum habitability standards (separate access, its own restroom, whatever other facilities are mininally required.)

[scoofy]

This is a general argument assuming units being arbitrary. Units should be effectively arbitrary, but every town will have different rules.

[dragonwriter]

> This is a general argument assuming units being arbitrary.

Well, no, it doesn't assume units are arbitrary, it assumes units are fixed square footage, which they are not. Under most regulatory schemes, there is a practical minimum size or a habitable unit, but a pre-existing area zoned for detached single-family units exclusively is unlikely to be comprised of single-family units that happen to also be the minimum square footage for a habitable unit.

[scoofy]

The same concept, at a minimum, would need to be extended to units. This is what I mean by assuming it’s arbitrary. It’s just redundant to say that, yes, obviously you need an incremental increase in units, sqft’s, footprint, vertical footprint, etc.