The city administrator may authorize, where appropriate, the erection of fences, walls or hedges exceeding the applicable height limitations set forth in subsections (1) and (2) of this section, but not within the vision clearance area, to enclose a patio, swimming pool, garden supply, tool compound, or similar living, recreational or storage area or facility, and the fences and hedges enclosing it shall be considered as comprising an accessory use. The erection of fences exceeding 72 inches in height and certain walls are regulated by the building code and may require a building permit.