Palletised Storage: High Bay

'High bay' warehousing describes pallet racking up to heights of 30 - 35 m, in which the pallet movements is by means of stacker cranes, giving free access to all pallet locations. Aisle widths can be narrow as load plus side clearances. Because of the height, conventional APR is not generally strong enough to carry the imposed loads so structural steel is usually adopted. The racking structure may then be used to support the walls and roof of the building, that is, it becomes the building structure, hence the terms 'roof-on rack' and 'clad rack'. Because pallets are accessed by a stacker crane running on floor-mounted rails, the floor surface and flatness are not critical, although floor strength clearly is.

The advantages of High Bay warehousing are:

• Space utilisation is high- the use of height and narrow access aisles; and
• Stacker cranes, which can move very quickly, can be manually or automatically controlled, hence they are very suitable for automated warehouses.

The disadvantages of High Bay warehousing are:

• Special fire sprinkler systems may be required;
• High bay storage systems are expensive to build; and
• Little flexibility for subsequent change, thus design should be carefully based.