For uses denoted with a “U” in Section 32-191 (Use Group IX – general use allowances), a use may be open or enclosed without restriction except that:

1. boat storage in all Commercial Districts may be conducted outside a completely enclosed building only if located at a distance greater than 100 feet from a Residence District boundary;
2. building materials or contractors’ yards in C8 Districts may be open or enclosed provided that not more than 5,000 square feet of such lot area is used for open storage; and
3. public parking garages, in all applicable districts, may be open or enclosed, provided that no portion of such use shall be located on a roof other than a roof which is immediately above a cellar or basement.