Except as hereinafter provided, no building
or structure or part thereof shall hereinafter be erected, structurally
altered, enlarged or rebuilt except in conformity with the lot dimension,
yard, coverage, height and spacing regulations herein prescribed.
Any building or structure that does not conform to such regulations,
hereinafter referred to as the "building regulations" of this chapter,
shall be deemed a nonconforming structure, irrespective of the use
to which it is put. Building variances granted on grounds of practical
difficulties or undue hardship shall be deemed to be nonconforming
structures or uses.