In most projects, the storage and throughput requirements are defined based on the proposed process and projected volumes and then the goal is to optimize productivity, storage density, and capital cost. The following factors are considered when deciding the appropriate storage medium for the warehouse.

• Product characteristics
  
  The unit load dimensions of the various products to be stored must be known. The methods used to support unit loads include pallet boards, skid, slip sheet, tote, pan, or other storage containers. This unit load support method is an important ingredients in determining the storage medium and the until load handling equipment. The product mix must be determined next. What percentage of the receipts and shipments are full pallet loads, full cases, broken cases? These product types dictate specific types of storage racks. For eg.if there is a group of fast-moving products, then dense systems such as double-deep rack, drive-in rack, or floor stacking are good options for reserve storage. If many products are slow movers, then a high degree of selectivity is necessary and single-deep rack and narrow aisles must be considered. Does the product have a specific shelf life? Does the product require special handling and access such as chemicals or hazardous materials? Is first in first out (FIFO) inventory control required? These types of products require easy access to every product at any given time and affect the storage selection

• Material handling equipment
  
  The type of material handling equipment used to service the storage medium affects the selection. The selectqed rack should not require the forfeit of square footage to accommodate the material handling equipment. Lift trucks have different turning radii that define the operating aisle widths and clearances required. Usually, a storage medium is chose and then a compatible lift truck is selected. If there is a requirement to use existing equipment or the equipment or the equipment is selected first, this information must drive the storage- medium analysis.

• Throughput requirements
  
  The amount of unit loads required for storage and retrieval each hour or shift is calculated. The trend is toward having real-time information and EDI available in order to increase inventory turns and allow functions such as cross-docking. It is important to take this into consideration as it reduces the amount of storage medium required. Storage itself should not be the objective but rather the movement of inventory through the distribution center. The movement of inventory to customers makes the company money, not the amount stored in the warehouse.

• Layout considerations
  
  The storage medium is constrained by building obstacles and layout requirements, including ceiling heights, columns, air ducts, light fixtures, floor specifications, sprinkler systems, and other elements.

• Aisle widths
  
  Within each storage mediums, the aisle widths can be varied to accommodate the level of activity. Is it important for lift trucks to be able to pass each other? What lift trucks will be operating in these aisles? How many lift trucks are required to meet the throughput rates, especially during peak periods?

• Budget considerations
  
  Compromises must be made in an effort to keep the system as simple as possible and still meet the project objectives. It is necessary to decide what is important in terms of the investment required and the benefits obtained.