In a Residence BB District, no building or premises shall be used and no building shall be erected or altered for other than one or more of the following specified uses:

The building area shall not exceed 35% of the lot area.

There shall be a required front yard which shall be not less than 25 feet in depth, except that where a multifamily dwelling is erected or an existing building is converted to a multifamily dwelling, the required front yard shall not be less than 35 feet in depth.

There shall be two side yards, one on each side of the main building. Each side yard shall not be less than six feet wide, except that where a multifamily dwelling is erected or an existing building is converted to a multiple dwelling, each side yard shall not be less than 30 feet.

There shall be a required rear yard which shall have a minimum depth of 35 feet.

No building shall be erected upon a lot that has a street frontage and minimum lot width at the front and rear wall of the principal building of less than 50 feet and a lot area of less than 5,000 square feet, except that where a multifamily dwelling is to be erected or an existing building is to be converted to a multifamily dwelling, the provisions of Article IV of this chapter shall apply.

No building shall be greater than 2 1/2 stories or 35 feet in height, except that no multifamily dwelling hereafter erected or any building hereafter converted to a multifamily dwelling shall be higher than that which is permitted pursuant to the provisions of Article IV of this chapter.