It is important to note the Residential volume of the building code, while not addressing setbacks, that is a Zoning issue, does address fire separation distance. Exception 7 applies specifically to zero lot line development. It is admitted this is not a zero lot line development. This appears to be a residential property with a zoning variance to build to the property line. The adjacent neighbor could apply for the same or a similar variance. The wall supporting the shed roof on the far end is not on the zero-lot line. It is not a roof overhang projection as it is supported by posts at the property line. As such, it must be built to the standards of R302.1 with the possibility of using any of the other exceptions that may be applicable. For the general rule, according to table 302.1, a minimum 1 hour fire resistance rating with a 2 foot dimension to the property line appears to be the minimum.
