Multiple dwelling: 1 1/2 per dwelling unit; at least 60% shall be enclosed parking. In addition, all outdoor off-street parking shall be subject to approval by the Board of Trustees, and plans therefor shall be submitted with each application. The Board of Trustees, after due public notice and hearing and subject to appropriate conditions and safeguards and in harmony with the general purpose and intent of this chapter, may approve the same if the use is found reasonably necessary for the health, safety, convenience and general welfare of the village and the residents thereof and for the proper and facilitated movement of traffic through the village and the parking of automobiles, and if it is further found that the use will not unreasonably depreciate or impair the value of the buildings, lots and premises in the neighboring territory in the village. Front yard, rear yard and side yard requirements shall be as determined by said Board of Trustees, and the provisions of this section shall apply also to nonconforming multiple dwellings and apartment houses.