Improving space, efficiency and productivity in your storage space is rarely an easy task. Balancing space consumption, pick selectivity and storage density is a challenge no matter your application. We’ll tackle all these challenges and more! Our complete guide will take you through the many steps to maximize your warehouse space. Topics include:
- Floor Stacking/Block Stacking
- Selective Racking
- Double-Reach Racking
- Drive-In or Drive Through Rack
- Push-Back Racking
- Pallet Flow
Regular/Wide Aisle - 10.5 Feet or More
Your average sit-down forklift will utilize wide aisles. Which means you won’t need to invest in specialty equipment. Much of the available storage space is devoted to the aisles rather than the racking.
Narrow Aisle (NA) - 8.5 to 10.5 Feet
Narrow aisles allow you to pack more product into your facility. But, it'll require equipment with a tight turn radius to avoid hitting the racking. 3-Wheel forklifts have a tighter turning radius and would be able to work in narrow aisles. Order pickers and reach trucks are other options for narrow aisle operation.
Very Narrow Aisle (VNA) - 5 to 7 Feet
Very narrow aisles give you the ability to greatly increase capacity without expanding the footprint of your facility. You should take into account the added costs of very narrow aisle forklifts, if you don’t have any in your fleet. Training your employees on the new equipment will incur additional costs as well.
If you aren’t interested in purchasing new equipment to suit your aisles, you can easily calculate the minimum aisle width you’ll need based on your current fleet.
Calculating Forklift Aisle Widths
Use this simple equation to determine the minimum aisle width you’ll need to accommodate your forklifts.
Basic Right Angle Stack of Forklift
12 Inch Clearance
Maximum Load Length
Minimum Aisle Width
Basic Right Angle Stack: minimum amount of space a forklift needs to turn and enter pallet. Found in specification manuals. (Doesn’t include length of load)
Clearance: 12 inches of clearance gives enough space to turn forklift in aisle and gives a margin of error for operators without damage to the racking.
Load Length: varies depending on circumstances. Standard pallet is 48 inches in length – good rule of thumb for preliminary calculations. Make sure to use the exact load length for a more accurate representation.
Don't forget to use the same unit of measurement for all areas of the formula. Take a look at the example below!
Basic Right Angle Stack
Maximum Load Length
Minimum Aisle Width
In this example you end up with a 142 in. minimum aisle width. Or almost a 12 foot aisle. This would be a regular aisle width (not narrow or very narrow).
Now that you’ve calculated the aisle width you’ll need, let’s look at the different storage systems you could use.
Do You Need Pallet Racking?
It’s time to determine: do you need racking? Many storage systems involve racking, however for certain applications, racking may not be necessary.
Floor Stacking/Block Stacking
Floor stacking is a common technique used in warehousing. Pallets are simply stacked on the floor in rows. This system can be arranged to provide extremely high density storage if the pallets or loads can be stacked directly on top of each other. Generally floor stacking works best for First-In, Last-Out inventory management.
- No cost for racking system
- Opportunity for high storage density
- Low pick selectivity – requires more labor to retrieve the right pallet
- High space consumption
For applications that require a racking system there are several options ranging in cost, accessibility and storage density. Racking systems can be custom designed by your dealer or purchased individually.
Selective Racking: One pallet Deep
Since selective racking is one pallet deep, the racks themselves can be placed either back-to-back or against walkways. This system provides unobstructed access to each pallet within the system which is ideal for the First In, First Out inventory systems. Selective racking is well-suited to applications with low inventory turnover along with high product differentiation.
- Low cost
- No specialty forklifts required
- Accommodates products of any volume, weight, or size
- All stock is visible and accessible
- Low risk of product damage
- Low storage density
Double-Reach Racking: Two Rows Deep
Double-reach racking or double deep racking systems are very similar to selective racking. Instead of using one row of racking, or back-to-back rows, racking is placed two rows deep. Racking could even be placed both back-to-back and two rows deep on each side, therefore maximizing density.
This system offers more pallet positions by reducing the number of aisles and must use a First-In, Last-Out (FILO) inventory system.
Double-reach racking is well suited for applications with multiples of the same stock.
- Cost effective
- Higher storage density
- Reduces pick selectivity
- Specialty forklift required – which may add cost if not currently part of fleet
Drive-In or Drive-Through: Rails
With drive-in or drive-through racking, pallets are stored on rails in place of shelf beams. These rails extend the length of the rack and allow forklifts to drive into the racking structure for pallet placement and removal.
These racking systems work best with a First-In, Last-Out (FILO) inventory system.
Drive-in racking is ideal for storing a limited number of SKUs with uniform pallets sizes and load measurements. Which allows for consistent load rail heights.
- Increases pallet positions
- Requires less warehouse space
- Reduced pick selectivity
- More opportunities for impacts or contact between forklift and racking
Push-Back Racking: Nesting Carts
Push-back racking consists of a series of nested, mobile carts which then glide on rails. The pallets are placed on carts and stored in bays two to six pallets deep. When a new pallet is loaded onto a cart, it pushes the other carts back.
This system is ideal for First-In, Last-Out inventory management.
Push-back racking is best used when there is minimum storage space available and when the product being stored is consistent in size and weight.
- High storage density
- Reduces picking time
- Requires fewer aisles
- No specialty equipment necessary
- More expensive storage option
- Potential for lost pallet positions due to size of mobile carts
Pallet flow allows up to 20 pallets to flow down an incline on a series of rollers or wheels. The pallets are loaded on one end of the system and unloaded at the other end making it optimal for First-In, First-Out inventory management.
This system is an excellent option for applications with a very limited number of SKUs in large volumes. It also works well for perishable or time sensitive products.
- Increased product selectivity
- Superior density
- High expense per pallet position
- Potential for lost pallet positions – system is on an incline which takes up more space
- Pallet flow system requires maintenance
Pallet Rack Comparison Chart
We've compiled this quick pallet rack comparison chart to help you decide which option works best for you and your facility.
|Racking Type||Ideal For:||Specialty Equipment Required||Storage Density||Inventory Management System||Cost|
|Selective||Products of any volume, weight or size||No||Low||FIFO||$|
|Double-Reach||Multiples of the same stock||Yes||Medium||FILO||$|
|Drive-In||Limited number of SKUs with uniform measurements||No||Medium||FILO||$$|
|Push-Back||Products consistent in size and weight||No||High||FILO||$$$|
|Pallet Flow||Very limited number of SKUs in large volumes||No||High||FIFO||$$$|
Damage to Your Pallet Racking
Now that you’ve discover the ideal racking for your warehouse, the last thing you want to see is damage. Most rack damage is caused by overloading, inadequately engineered systems or incidents with forklifts.
These issues can cause the center of gravity to shift away from the rack column at the base plate. This offset causes the column to bend, which creates horizontal force and pushes the column toward the load center. This cycle – called micro-shifting – continues until the racking structure becomes so unstable that a relatively minor impact can cause a major collapse.
Protecting Your Racking
To combat damage to your racking and micro-shifting, you can add additional layers of protection to your racking system.
Column Protectors shield the post or column against impacts with a forklift.
End Guard Rails protect the end of each row of racking against forklift damage.
Off-Set/Cant Legs are sloped and recessed legs on the lower, front column of the pallet racking frame to provide more clearance for forklifts.
Rub-Rail (for Drive-In Systems) is anchored to the floor and acts as a bumper for forklifts to protect the racking.
Inspections of your racking system should be completed either weekly or monthly (depending on your usage) to evaluate their overall condition. Check for damage indicators like:
- Beams not engaged with the columns
- Unengaged safety locks
- Missing safety locks
- Damaged uprights
- Damaged bracing
- Deformed beams dues to load impact
Preventing Operator Damage to Racking
One of the major ways to prevent forklift operators from damaging your racking is training. Operators should know the procedures for operating near racking. These procedures may vary slightly given your facility and racking type. However training is just the tip of the iceberg. Read more on preventing forklift operator damage to your racking.
Now that you’ve calculating the right aisle widths, picked a racking type and learned how to prevent damage to your racking system, it’s time to optimize your warehouse space.
Warehouse Space Saving Solutions
Your racking system isn’t the only factor affecting your usable storage space, efficiency and productivity. Optimizing your product placement, floor space, beam placement and utilizing mezzanines can help you gain storage space without adding to your facility’s footprint.
The Pareto Principle states that 80 percent of your activity will come from 20 percent of your products or SKUs. To most effectively utilize time and space you must determine which products cause the most activity. Make the highest selling products or the most frequently ordered products the most accessible to your operators. This change can:
- Increase productivity
- Reduce operational expenses
- Enhance employee satisfaction
- Improve space utilization
Beam Placement and Selection
Only six inches is required between the beam and the top of the stored product. This space is reserved for forklift interaction. Some companies allow for more than six inches here, but if your space is limited you may want to stick to the required six inches. Even two inches of extra space in addition to the required six can add up to a huge amount of underutilized space when multiplied by all your pallet positions.
Clean Floor Space
Whether you use racking systems or floor stacking, your vertical floor space is extremely valuable and should be reserved for active inventory. Any obsolete inventory should be removed. If you have unused equipment taking up floor space in your warehouse, evaluate its condition and determine if it can be resold. If the equipment might be used at a later date, consider storing it at another location.
In order to maximize inventory storage, other items such as supplies, small parts, equipment, files, and even offices can be relocated. Mezzanines provide the opportunity to increase usable square footage without actually expanding.
For even more space saving tips, watch Toyota’s video – Warehouse Planning 101 to see four ways to optimize your warehouse space.
Optimizing your warehouse starts with optimizing your aisles, racking systems and space. The result will be an efficient space that fosters productivity without sacrificing safety. This challenge of balancing space consumption, pick selectivity and storage density, isn’t an easy one to overcome.
Share this guide: