Greater Boston has wide swathes of triple deckers, which are a 3-4 story (depending on basement status) compromise between the detached house and the 5-story ap

Greater Boston has wide swathes of triple deckers, which are a 3-4 story (depending on basement status) compromise between the detached house and the 5-story apartment block. They were illegal to build for a period of ~90 years though, allegedly due to concerns over fire. It's curious they never consider the obvious solution to that (building out of masonry instead of timber) though.