MECHANICAL minimum code.
Extend the existing furnace ductwork, supply and return, to the new addition, or add a small heating unit to the space. Chances are that the existing unit will not be large enough to handle the added load, so if you were relying on it for heat, the entire heating system would have to be zoned, or a larger furnace and ductwork installed.
The minimum is to add the ductwork, call the mechanical inspector and ask him/her if that would be acceptable.
Last edited by 8 Ball; 08-15-2008 at 05:42 AM.