If the common wall has roof and floor structural members supported on ledgers and secured in buckets anchored to the common wall that common wall is not structurally independent and is in violation of R302.2.4 as well as FBC-B 706.4.1.2. The arrangement described goes beyond the exception in 706.4.1.2(3) which states that said wall may be penetrated by roof and floor structural members provided that the fire-resistance rating and the structural integrity of the wall is maintained.
If the common wall has roof and floor structural members supported on ledgers and secured in buckets anchored to the common wall that common wall is not structurally independent and is in violation of R302.2.4 as well as FBC-B 706.4.1.2. The arrangement described goes beyond the exception in 706.4.1.2(3) which states that said wall may be penetrated by roof and floor structural members provided that the fire-resistance rating and the structural integrity of the wall is maintained.
Yes and yes; We have traditionally viewed structural independence to mean that either side of the common wall could have complete structural collapse without affecting the common wall and the other side. A floor truss system attached to the common wall by a bolted on ledger and/or bucket has typically been viewed as allowing such collapse and therefor has been approved. Without a clear definition of "structurally independent" in the Residential Code I think we can look at the Building Code for guidance, particularly 706.4.1.2 and 706.2 "Structural stability. Fire walls shall be designed and constructed to allow collapse of the structure on either side without collapse of the wall under fire conditions. Fire walls designed and constructed in accordance with NFPA 221 shall be deemed to comply with this section."
I believe the traditional view of structural independence is still correct.
It is interesting that the 2014 FBC Residential section R302.2.4 "Structural Independence" had 5 exceptions instead of 4. The 5th exception that was removed from the code stated " Townhouse separated by a common 1-hour fire resistant rated wall as provided in section R302.2" I think it must have been removed as it could have been interpreted to mean no structural independence was required at all.
