All buildings shall use durable high-quality material requiring low maintenance, such as brick, stone, stucco, glass, precast concrete, and wood, when properly treated. Where durability and performance are questionable, the applicant may be asked to provide a manufacturer's guaranty or proof of durability from an independent testing laboratory certification. The use of aluminum siding, vinyl siding, and exposed concrete block are prohibited, except for architectural prefinished block and split face block, which are permitted.