Expert Insight: Sorting it Out
  By Cliff Holste  
     
  February 21, 2008  
 

Designing Your Distribution Center from the Inside Out

 
     
 

Careful Planning Upfront Pays Big Dividends Later; Maximizing Flexibility in Storage and Material Handling System Options

 
     
 
Holste Says:
It is critical that distribution professionals and facility planners be aware of the impact of building design on technology deployment.

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The good news is your business is growing in leaps and bounds.  Congratulations!  However, the not-so-good news is you’ve outgrown your current facility and it’s time to start looking for a new one.  As you begin your search, you will find that architects and building contractors are well aware of your general warehousing and distribution requirements.  If your business fits the standard model, you’re in luck because most industrial parks have a ready inventory of various size “spec” buildings to pick from.

By now you know that market forces are making the traditional concept of “warehousing” virtually obsolete.  Due to changing order profiles and customer value added requirements, along with a much greater recognition of the role supply chain logistics plays in reducing cost, most companies now need a flexible distribution center operation that focuses on high inventory turnover, frequently changing customer order fulfillment profiles, increased demand for VA services, and shipping of high-velocity goods, not just static storage.

Unfortunately, most new buildings available for distribution operations are still constructed using the traditional warehouse model.  This means that opportunities for optimizing material handling automation and storage/retrieval technologies, like cross docking for high-throughput distribution may be lost.  It is critical that distribution professionals and facility planners be aware of the impact of building design on technology deployment.  Whenever possible, material handling and storage systems should be designed and integrated with a physical building design that ideally supports the requirements of those systems.

Let’s take a few minutes to consider the key building design criteria that should be considered to optimize distribution center performance.

  • Size:  While size is an obvious factor, there are several considerations often overlooked when determining square footage requirements.  The first is the opportunity to reduce total building costs by going up to increase cube, rather than out (see “Building Height” below).  The second is that while material handling automation such as picking and carton sortation systems can deliver significant productivity gains, it also takes floor space that must be planned for.
  • Building Height:  A traditional “spec” building will have a clear height of 24 to 26 feet, tall enough for 4-high pallet storage racking.  However, as it is usually less expensive to build up rather than out, and maximizing storage capacity is an almost universal goal, the trend today is to build with a clear height of 32 feet or even greater.  At this height, 6-high pallet storage can be used, with some companies going even higher to achieve 8-level storage rack configurations.  In most municipalities, fire safety codes have being written to permit ESFR (Early Suppression, Fast Response) ceiling mounted sprinkler systems to be installed in buildings of this height in place of in-rack fire sprinkler systems.
  • Floor Flatness:  Standard warehouse floors will support normal fork truck movement and activity, but are generally used with conventional, wide-aisle storage configurations (12-foot aisle between racking).  Standard floors may preclude use of narrow aisle (8-foot aisles) and are definitely not acceptable for very narrow aisle (5-6 foot aisle) technology, which require so-called “very flat” and “super flat” floor construction, respectively.  While these floors are more expensive to install and can add weeks to the project schedule, the long-term gains in storage cube, operator productivity due to faster travel speed, and reduced truck maintenance are often worth the one-time initial building cost.  To make this decision, an analysis is required to determine total storage requirements and the optimum rack configuration by comparing building cost, the cost of specialized lift truck equipment, pallet storage density, and expected worker productivity.
  • Column Grid Pattern:  The traditional 40-foot by 40-foot building column spacing is rarely optimum for an engineered DC.  Roof support columns should always be located in the flue space in-between racks.  However, with any of the narrow aisle approaches a standard grid will rarely allow the columns to be buried in the rack, resulting in a significant loss of storage positions.  It is also frequently desirable to make the first bay extra deep to eliminate columns that impede fork truck traffic on the dock, by moving the first column row back to 60-70 feet away from the doors.
  • Roof Reinforcement:  It is often possible to hang portions of the material handling automation system from the ceiling rather than using floor supports.  This can both provide for greater movement of vehicles and people around and through the system, as well as allow those portions of the system to occupy otherwise “dead space,” such as above a traffic aisle.  However, the ability to hang conveyors and other equipment is generally dependent upon having defined sections of the building roof structure strategically reinforced during construction to take a greater load per square foot.
  • Dock Doors:  The typical warehouse building has receiving doors on one side of the building, and shipping doors across on the other side.  While this flow-thru design is often the best configuration, it is sometimes better to look at other arrangements.  For example, placing receiving and shipping doors on the same side of the building may allow both functions to share sortation equipment, using one set of diverts to sort received cartons for palletizing and put-away, and another to build outbound customer orders.  Another advantage is that you can provide one common and secure space for both delivery and pickup drivers to congregate.   While there is usually flexibility to add doors even to a spec building, the final arrangement of doors needs to be closely tied to the material handling system layout, especially for fluid loading and unloading applications.
  • Lighting:  Lighting should be placed so that it hangs directly above storage and pick aisles, which will rarely be the case if lighting is in place before the storage system has been designed and laid out.

Whenever I visit a facility that includes the above design features, and that has been in operation for several years, it is obvious to me, as it would be to anyone, why it is so important to design from the inside out.

 
 
 
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