[RB] TOWNHOUSE. A single-family dwelling unit constructed
in a group of three or more attached units in which
each unit extends from foundation to roof and with a yard or
public way on not less than two sides.
R101.2 Scope. The provisions of the International Residential
Code for One- and Two-family Dwellings shall apply to
the construction, alteration, movement, enlargement,
replacement, repair, equipment, use and occupancy, location,
removal and demolition of detached one- and two-family
dwellings and townhouses not more than three stories above
grade plane in height with a separate means of egress and
their accessory structures not more than three stories above
grade plane in height.
NJ code must have a different definition and doesn't require that one and two family dwellings to be detached.