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Building an additional storey to an existing hospital

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Hi,

	I have a question wrt to building an additional storey to an existing
hospital.  The hospital was built in the early 70's with provisions for
building an additional 6 stories.  It was designed as a ductile moment
resisting concrete framed structure with a R factor of 4  (state of the art
for the 70's), therebye decreasing the elastic base shear by a quarter.  We
wish to add an additional steel framed storey therebye minimizing the the
seisimic effect of the storey on the original design.  I have analyzed the
original structural dwgs and have found that the original design does not
meet the current code requirements, 1995 NBCC, for even a R factor of 2, a
nominally ductile moment resisting frame.  It is lacking specifically
seismic hoops with 135 degree bends and closely spaced hoops at potential
plastic hinge locations.  My question is are we obligated to retrofit
seismically the orginal building before proceeding with our additional
storey?  We have heard that the design will not proceed if we propose an
expensive and time consuming retrofit of the existing structure.  Also the
zonal velocity ratio for our area is 0.1.