In all dwelling units there shall be at least one bedroom containing at least 140 square feet of habitable floor area. Other full bedrooms shall contain at least 120 square feet of habitable floor area. There shall also be required additional floor area in the amount of 25% of the total amount required as hereinabove set forth, for such purposes as (but not limited to) dead storage, utilities, service, recreation or other, except parking. This related space shall be provided in basements, attics or accessory buildings.