Warehouse floors aren’t all built the same; and not all slabs can safely support heavy-duty racking systems. Before installing pallet racking, mezzanines, or dense storage blocks, you need to confirm your concrete floor’s load rating.
Whether you're planning new racking or reconfiguring existing layouts, checking the slab’s point load, distributed load, and reinforcement is essential. Failure to do so can lead to cracking, deflection, or even collapse; especially in older or lightly reinforced floors.
Racking systems place heavy, focused loads on small areas; typically under each upright leg. This is called a point load. In contrast, forklifts spread their weight over a larger tyre footprint (a more distributed load). A slab that supports vehicle traffic might still fail under static racking unless designed for those concentrated loads. Always confirm the maximum point load capacity (kN) at a given slab thickness and reinforcement level before anchoring racking.
A 150 mm ground-bearing concrete slab with mesh (e.g. A193) may only support point loads of 30–50 kN depending on sub-base quality. In contrast, a 200 mm steel fibre slab can support 75–100 kN+ per point. Raised access or suspended slabs may be even lower. Most pallet racking legs exert 40–90 kN depending on bay height and pallet weight. Always have a structural engineer calculate real-world slab performance; including factors like joint position and load eccentricity.
If you're retrofitting racking into an existing warehouse, don’t assume the slab is adequate. Older floors may have been designed for light traffic or may have unknown reinforcement. Request original as-built drawings or conduct a core test and ground-penetrating radar (GPR) scan. If no documentation exists, a structural engineer can back-calculate approximate load capacity based on core samples and visible joint layout.
The weakest areas of most slabs are construction joints, perimeter edges, and corners. Racking legs placed too close to joints can cause slab spalling, cracking, or long-term joint deterioration. Try to position upright legs at least 300–500 mm from joints or edges where possible. If unavoidable, consider reinforcing the area with additional dowels or resin repairs to spread the load more effectively.
Most racking manufacturers provide upright baseplates, but in high-load situations, these should be upsized or custom-designed to distribute weight more evenly. A larger plate reduces stress per mm² and can help avoid slab crushing or punching failure. Make sure anchor bolt spec matches the concrete’s strength class (e.g. C35/45), and torque settings are correct to avoid microcracking.
Even if your slab seems strong, always involve a structural engineer when installing racking; especially if loads exceed 30 kN per point. They can assess slab thickness, reinforcement, sub-base conditions, and spacing. This is especially important for very tall racking, narrow-aisle systems, or ASRS installations. Sign-off ensures regulatory compliance and protects liability if a floor fails under load.
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