DC Velocity - January 2009

Maximum Experience . . Minimal Risk .

vol.08 issue.02

AN EDUCATIONAL SERIES DEVELOPED BY HK SYSTEMS

A Case For:

A Comparison Of

Rack-Supported vs.

Conventional Buildings

The decision to construct a new warehouse often includes endless hours devoted to site selection and the type of material handling equipment and technology to be used to support the new facility. Often, it becomes a foregone conclusion that the facility will be a steel frame structure with freestanding rack. This conclusion, however, deserves greater debate as there are many attractive reasons to consider a rack supported structure . . . in some cases.

STEEL FRAME VS. RACK SUPPORTED STRUCTURES

Structural steel frame buildings are the most common construction style in use for today’s warehouses. Utilizing a “skeleton frame” of vertical steel columns and horizontal I-beams or trusses, the building is constructed in a rectangular grid to support the roof and walls which are all attached to the frame. The building is then equipped with freestanding rack for material storage. In contrast, a rack supported building is comprised of a complete storage rack system, with the rack system being the basic structural support for the building’s roof and walls. In this scenario, the roof and walls are often referred to as the “skin.”

COMPARISON

A side-by-side comparison of the two styles relies primarily upon the intended use of the facility. For pure storage purposes, the rack-supported structure has many benefits. On the other hand, if other business processes are interspersed with that of material storage, or if business requirements might force a change in the building’s overall configuration, a steel frame building might prove the best choice.

Conventional

For storage considerations, a rack-supported building will far exceed the space utilization that can be offered by steel frame buildings. The infrastructure needed to erect a steel frame building in excess of 45’ becomes prohibitive when considering the relatively small amount of resulting storage. (Thus, rack-supported buildings are almost always preferred for tall AS/RS applications) The columns and aisles take up an excessive amount of space that decreases the overall utilization. Conversely, rack-supported buildings are generally targeted for applications that range up to 110’, and provide a dramatic improvement in space utilization and footprint, as evidenced by the following example.

Rack- Supported

Comparison For Building With 15,000 Very Narrow Aisle Rack Locations

Building Floor Space Storage Square Feet Style Height Utilization (Square Feet) Per Pallet Position

Steel Frame 40' 55% 126,000 8. 3 Rack Supported 90' 72% 36,000 2. 4

From an economic standpoint, a rack-supported building has some additional benefits. In many instances, open space laws require a set amount of acreage be set aside for every one acre that is built upon. As demonstrated, the rack-supported building can minimize the structural footprint, and can thereby also minimize the required “set aside.” This can affect your bottom line directly by reducing the necessary investment in land, or by allowing for more acreage to be used for productive purposes.

Depending upon the tax laws and codes that apply to your particular company, a rack-supported building might also provide substantial tax benefits. Typically, buildings must be depreciated over the course of 30 years. But because the walls and roof of a rack-supported building are considered to be equipment enclosures, the cost can be depreciated over the course of 15 years (depreciation of equipment rather than of a building).