wood framed townhomes airspace building separation

huangyhg

wood framed townhomes airspace / building separation
ubc section 1633.2.11 states that airspace between two buildings needs to be taken to the consideration of delta m.  which is known to be roughly 6" per story.  it is very impractical for townhouses/multi family projects, a typical townhouse project has about 2"-4" airspace at party walls. since the intention of this code is to prevent the "hammaring" action between two buildings, one way to solve this problem is to tie both buildings together.  however, this violates both the fire code and the definition of townhouses which require the airspace to be "clear".  base on my experience, some cities encourage such connection between buildings while some don't even allow.  i would like to see is there anyone can come up with a more creative way to resolve this.