Yes, multi-family buildings have to have closed combustion systems. However, both multi- and single-family buildings are exempt from this requirement if the combustion system is in a detached utility building or an open-air facility (e.g. roof). If a builder can demonstrate an alternative design that meets the intent of this requirement, specific details of the system design must be submitted and the TASC will consider it.
Updated 10/1/13 for rating system applicability.