Load capacity is a critical consideration for any business that utilises warehouse racking.
Understanding load capacity is the first step to ensuring your racking can support the items it will be tasked with storing. By choosing the correct warehouse racking load capacity you can guarantee the stability and safety of the structure.
The consequences of ignoring or incorrectly diagnosing racking system load limits can be dire: operational disruptions, damage to inventory, and most critically, potentially endangering your workers (and the often significant financial liability for any incidents).
There’s perhaps more nuance to load capacity than you might imagine – it’s not as simple as a one tonne shelf handling a one tonne load. You need to make racking safety calculations while considering factors like the weight distribution on the floor and total bay loads on warehouse racks.
In this guide we’ll walk you through the intricacies of warehouse shelving load capacity: what it is, how to calculate it, and the keys to keeping your team safe while meeting New Zealand regulatory responsibilities.
Understanding load capacity: what it really means
Load capacity refers to the weight that a section of warehouse racking can safely hold.
It’s a simple definition, but if you’ve ever attempted to read a safe working load (SWL) sign, you’ll know that load capacities come in a number of different flavours, including:
- Pallet capacity: The maximum weight allowed per pallet Capacity per beam level: The maximum weight a single beam level (two beams) can handle.
- Total capacity per bay: The maximum weight a single bay can handle.
But the figures above tend to be based on static, evenly distributed loads. Warehouse racking load capacities can decrease when asked to handle:
- Uneven loads: Loads with odd weight distribution – i.e. the centre of mass is not at the centre of the load.
- Dynamic loads: Loads where the centre of mass can move, such as when a forklift places a half-full IBC on warehouse racking, causing the liquid inside to move, which places unpredictable stress forces on the structure.
Finally, there are some key structural factors that you need to consider regarding warehouse racking load capacity:
- Beam deflection: Excessive sagging of horizontal beams under load can reduce structural integrity. Load ratings are based on an acceptable deflection limit.
- Racking height: As height increases, the racking loses stability. Taller racking may demand additional bracing.
How to calculate load capacity for your racking system
Load capacity calculations consider the following key factors:
- Beam length and profile: Longer beams deflect more under weight; thicker or deeper profiles can support heavier loads.
- Upright frame strength: This is key to determining the total weight the bay can handle, and varies by material, design and height.
- Rack configuration: Overall capacity is affected by factors like the number of levels, the spacing between beams and the presence of bracing.
- Floor bearing capacity: It’s not all about the racking – the surface below must be capable of supporting the total weight of fully loaded racking.
How do you calculate racking system load limits? First it’s important to note that the SWL will be defined by the racking manufacturer/supplier. Once you have those basic numbers, you can calculate the load capacity for different parts and sections of the structure.
As an example, let’s say you have a rack with three beam levels per bay. You want to add a fourth.
- Each beam level is rated for 1,000 kg
- The upright frame is rated for 3,000 kg total per bay
- Floor slab can support a load of up to 10,000kg
The limiting factor here is the upright frame. Its load capacity is 3000kg, and it is already holding 3x 1000kg-rated beam levels, so you cannot add a fourth level in the current configuration.
Proper weight distribution: avoiding point loads and imbalance
Evenly distributing weight is critical for warehouse racking safety. It minimises the risk of items falling and your racks collapsing due to unnecessary stress.
You should train your team to stack pallets so that weight is evenly distributed, and the centre of mass is spread evenly. . You should also avoid uneven load placement on shelves and racking – if a pallet is placed at one end of a beam, the next pallet should be placed at the other.
First in, first out (FIFO) and last in, first out (LIFO) systems can complicate things for your warehouse workers, who are tasked with moving loads through the facility as efficiently as possible. Train and regularly reiterate correct weight distribution principles with your team, such as keeping the heaviest loads at the bottom of levels and stacks.
Load signage and compliance in New Zealand
“The racking system should clearly display the maximum safe working load and any specified load configurations. The forklift driver should be able to see this notice so they know how much loading allowance they have left.”
SWL signs will be supplied with your racking system. You simply need to mount them in a conspicuous spot and abide by them.
Regular inspection and maintenance for load integrity
WorkSafe NZ also offers general guidance on inspections:
- Regular inspections: “You should inspect [the racking] or arrange for someone at your work to inspect it regularly. How often an inspection is carried out will depend on the specifics of your site and the operating conditions of your business.”
- Annual inspections: “You should arrange for the supplier, manufacturer or other competent person (in line with AS/NZS 4084:2023) to inspect the racking system at least once every 12 months.”
These inspections should look at all key parts of the structure: beams, uprights, bracings, fixings, floor, signage and load compliance. Look out for general wear and tear, and signs of load stress, such as buckling, beam bending and misalignment.
It’s important to maintain detailed inspection records, particularly for any issues identified and repairs made, to ensure you’re covered in terms of audits and compliance. If issues are found, you should tag those racking sections as “Do Not Use” until repaired.
Storepro: warehouse racking professionals
Warehouse racking load capacity and weight distribution is a complicated business, particularly for those who don’t deal in it day-to-day. Professional guidance can be invaluable to ensure your workers are safe, your business is compliant, and your warehouse runs as efficiently and effectively as possible.
At Storepro we are that professional. Our expert team is ready to offer all the load capacity guidance you need, while enhancing the performance of your storage space, through a custom designed, high quality warehouse racking solution.
Get in touch with our friendly team today for a free consultation, and take the first step towards smarter, safer, more efficient storage.