> Not sure what's impractical about a four story building?
Nothing impractical about a four story building as such. The (normally five story) Georgian terraces are normally very long and narrow, though. This makes them difficult to turn into practical housing; you're looking at either awkwardly long narrow rooms, or rooms without natural light, if you turn them into apartments (and as single unit housing they're far too big for practical purposes). They also make for awkward offices (I've worked in one, back in the day).
You could... maybe make wider faux-Georgian terraces, I suppose, but at that point you're getting into the weird-looking anyway.
Nothing impractical about a four story building as such. The (normally five story) Georgian terraces are normally very long and narrow, though. This makes them difficult to turn into practical housing; you're looking at either awkwardly long narrow rooms, or rooms without natural light, if you turn them into apartments (and as single unit housing they're far too big for practical purposes). They also make for awkward offices (I've worked in one, back in the day).
You could... maybe make wider faux-Georgian terraces, I suppose, but at that point you're getting into the weird-looking anyway.