No building shall hereafter be used, erected,
altered, converted, enlarged, added to, moved or reduced, wholly or
in part, nor shall any land be designed, used or physically altered
for any purpose or in any manner except in conformance with this chapter.
Where a lot is formed from part of a lot already occupied by a building,
such subdivision shall be affected in such a manner as not to impair
any of the requirements of this chapter with respect to the existing
building and all yard and other open space in connection therewith
and so that all resulting lots have adequate dimensions consistent
with the requirements of the zoning district in which they are located
and so that all lots have frontage on a street.