Building Height and Shape are key in determining the overall storage capacity of a building. When looking for a warehouse, square footage cannot be the only determinant as it is the combination of the two or cubic capacity which tells the whole story.
As well, it is important to know how many ground level picking slots are required, because even if the cubic capacity is correct, due to say a 38 or 40 foot ceiling height, the ground level square footage may not allow enough space for pick locations for each of your products, which topic will be covered in Part Two of this series.
Building height also has a material impact on your material handling equipment as only certain more costly equipment works as you get into more than 28 foot building heights. Another factor in the Building Height equation is land value. For example, in the UK and Europe, land values are extremely high and therefore it is easier to justify much higher buildings with a smaller footprint even up to crane environments of 60 to 90 feet in some cases. In other regions such as North America where land is more plentiful and comparatively less costly, in most cases, buildings do not exceed 36 to 40 feet with the average around 28 to 30 feet.
In addition, building shape can also be a determinant of the labour productivity of a warehouse, where certain shapes can result in very long travel distances for the internal movement of product in the warehouse. Travel distance from doors to storage mediums both in and outbound should be minimized which is typically a factor of square versus rectangular building shapes with rectangular typically offering closer access/egress proximity for improved productivity. However, another key factor in the travel distance equation is the direction in which racking is aligned within the facility, either vertically or horizontally which is directed by our next point of dicussion, column spacing.
Column spacing is another critical factor in the selection or design of an optimal facility as it has a direct impact on fitting different types and configurations of storage racking. For example, different column spacings are more conducive to narrow aisle, 4 to 6 foot aisle widths and others to wide aisle 11 to 13 foot aisle set-ups. So agian before beginning the design and building selection process, it is important to know the nature of and velocity (volumes) of the product types you are going to handle through the warehouse in order to make an appropriate racking selection which will of course have an impact on which column spacing you select for the construction of a new warehouse; or which is the optimal column spacing for your business when slecting an existing warehouse for lease or purchase purposes.
Additionally, column spacing can also vary within warehouses either in different sections of the building, or in different run directions. For example, the pattern could be a square 40 by 40 foot pattern allowing for similar racking spacing in both directions, or say a rectangular 35 by 40 meaning different racking spacing depending on which direction the racking is laid out in the facility. The orientation direction of racking in a facility can not only impact the overall storage capacity, it can also impact on productivity due to affecting the run direction of the racks as described above.
Floor Thickness is another very important but sometimes neglected aspect of building design and selection. Specifically, the thickness of the concrete floor of a warehouse and substrate determines its’ load bearing capacity which of course has a direct impact on the weight of product and racking which can be stored on top of it. This is an item which is usually properly calculated in the case of new purpose built facilities, but in the case of purchasing/leasing a speculative building or an existing facility, make sure you check this out before sigh=ning a lease or offer to purchase or you may find yourself in a very expensive jam ! In the very rare case that all involved miss this type of calculation or make an error, dire consequences can result from a floor collapse resulting in product damage or the even more severe cases causing human injury to your workers.
Other points to keep in mind relative to warehouse floors are the need for different floor construction for temperature control facilities, especially in the case of freezer space and also from a drainage perspective in “wet” produce and dairy facilties. More rules of thumb relate to the avoidance of multiple floor heights in facilites, the need and importance of properly sealing and caring for your warehouse floor, and determing the need for specialized floor designs. For example, in the case of high level storage and reach equipment circa 36 feet and above, a pre-requisite is something called a “super flat” floor where lasers are used during installation to ensure the level of the floor which if out even by fractions of an inch can cause equipment to hit the racking at the top levels of the storage medium.
This concludes Part One of the Warehousing 101 mini-course, Part Two will examine the other Building Factors of Fire Protection, Roof Condition, Lighting and Power Availability. Subsequent parts will cover the balance of the building components identified in the Introduction including,
The Storage Medium(s)
The Dock Areas
The Processing Areas
The Material Handling Equipment
We hope you have found this mini-course of use and a source of insight into some of the finer points of warehousing design and operations.