Surface area of any building facade must be a material approved for use by a national model code published within the last three code cycles that applies to the construction, renovation, maintenance, or other alteration of the building. Wood must be properly painted, stained, protected, sealed or otherwise treated appropriate for the type of wood material used. Sheets of pressed wood or plywood material, not specifically engineered for use as exterior siding, are acceptable when applied to an accessory storage building.