On any nonconforming undersized lot existing as of the date of the adoption of this chapter, the construction, erection, alteration or expansion of any building that is a permitted use shall be permitted, provided that after such construction, erection, alteration or expansion the total lot coverage of all buildings on said lot shall not exceed 37%, and further provided that such construction, erection, alteration or expansion complies with all other provisions of the Zoning Ordinance and Building Code.