In the case of any freestanding new construction when the total gross floor area on the lot exceeds 3,500 square feet after the new construction, one required tree shall be planted for each 100 square feet of gross floor area or part thereof exceeding 3,500 square feet; provided, however, that even if gross floor area on the lot is less than 3,800 square feet, a minimum of three required trees shall be planted if the total gross floor area on the lot exceeds 3,500 square feet.