Introduction: Concentrated load and uniform load describe two different kinds of pressure on the same steel raised floor panel, and mixing them up sends buyers to the wrong FS tier.
A raised floor panel has to hold two very different things: a heavy cabinet standing on a small footprint, and a crowd of people, carts, or equipment spread across a wide area. Facility teams often compare those two numbers as if they were interchangeable, then wonder why a panel rated for a large uniform load still flexes under one loaded server rack. this guide walks through what concentrated, uniform, ultimate, impact, and rolling loads each measure, how the FS662 to FS2000 ladder organizes them, and why one number alone never describes a panel.
Concentrated load is force delivered through a small contact patch — a leveling foot, a caster, a cabinet leg, or the base of a machine. On a raised floor panel, that force travels down through a narrow area and into whatever supports the panel underneath. Because it enters through a small patch, the local stress under that patch runs far higher than the average stress across the whole panel surface. Beam references make the same point: a point load at mid-span creates a sharper bending moment and a larger local deflection than the same total weight spread evenly along a beam. Steel's high stiffness helps resist that bending, and stiffness spreads stress across the material — but it does not remove the local peak that a single heavy foot creates.
A 3000 N concentrated load is roughly the force a 300 kg mass would exert, and the FS2000 tier reaches ≥8900 N, close to 900 kg from one item. That is the scenario the number describes: one heavy object, one small footprint, one spot on the panel taking the full hit. This is why concentrated load is the figure electrical and mechanical engineers check first when a room will hold server cabinets, switchgear, or battery racks. The panel has to stay flat and stable under a load that never gets the chance to spread itself out.
Uniform load flips the picture. Instead of one point, the force is distributed over an area and expressed per square meter — 12500 N/m² at FS662 rising to 46000 N/m² at FS2000, which is roughly 1.25 tonnes to 4.6 tonnes spread across every square meter of floor. Deflection under a spread load tends to be gentler and more even, because no single spot carries a spike. The trade-off is scale: when the whole floor is loaded at the rated figure, the panel bends like a plate over its full span, and the sag accumulates across the surface instead of concentrating in one place. Two panels can look identical and still fail in completely different ways under these two loads.
The FS662–FS2000 range reads best as a ladder of six tiers, and each tier lists five numbers together: concentrated load, uniform load, ultimate load, impact load, and rolling load at two cycle counts. FS662 sits at the bottom with concentrated load ≥3000 N, uniform load ≥12500 N/m², ultimate load ≥9000 N, impact load ≥445 N, and rolling load values of 2946 N over 10 cycles and 2356 N over 10,000 cycles. FS2000 sits at the top with ≥8900 N concentrated, ≥46000 N/m² uniform, ≥26700 N ultimate, ≥1340 N impact, and rolling values of 8900 N and 7120 N. FS800, FS1000, FS1250, and FS1500 fill in the steps between them. The useful insight is that the ladder is not evenly spaced, and its properties do not scale at the same rate. Going from FS662 to FS2000, concentrated load grows by roughly three times, and ultimate load grows by roughly the same factor. Uniform load grows faster, about 3.7 times. Between FS1250 and FS1500, uniform load barely moves, from 33000 to 34500 N/m², while concentrated load climbs a full 1100 N. Anyone treating the FS number as a simple higher-is-better score will misread those steps. The practical approach is to match the tier to the load pattern in the room: identify the heaviest single item, then look at how much general floor loading the space carries across its area. Panel size and thickness are separate specification items, so the tier comparison itself rests on the published load values.
Ultimate load is the ceiling. It describes the force at which the panel stops behaving as a usable structural component — not the load it carries every day. For FS662, ultimate load is ≥9000 N while concentrated load is ≥3000 N; for FS2000, it is ≥26700 N against ≥8900 N. In both cases there is roughly a three-times gap between routine service load and the failure-level figure. That gap is the safety margin a designer leans on, and it is why the two numbers are never swapped for each other. Concentrated load tells you what the panel holds; ultimate load tells you where it gives out. Impact load and rolling load each describe a different kind of dynamic event, and neither behaves like a static weight. Impact load, from ≥445 N at FS662 to ≥1340 N at FS2000, covers a sudden shock — a tool dropping, a panel being set down hard, equipment landing on the surface. Rolling load covers weight that moves, such as a cart or wheeled rack crossing the panel. Two cycle counts are stated: 10 passes and 10,000 passes. The 10,000-cycle figure is consistently lower, with FS2000 dropping from 8900 N to 7120 N, because repeated traffic fatigues the panel and a surface that survives one crossing is not automatically rated for thousands. Static weight, sudden impact, and moving wheels load a steel panel in three distinct ways.
Load labels only help when they are read as a family. Concentrated load answers what one heavy item does to a panel, uniform load answers what the whole floor carries, ultimate load sets the failure ceiling, and impact and rolling loads cover shock and movement. The FS662 to FS2000 ladder arranges all five measures into six tiers, and the gaps between those tiers are not uniform — which is why the chosen level should follow the load pattern in the room rather than the largest number on a specification sheet. Published tier data for a 45% ventilation steel air-flow raised floor shows how each FS step shifts every measure at once. Comparing raised floor solutions on the same set of measurements is the quickest way to see which tier actually fits.
A：Concentrated load is force applied through a small contact patch, such as a cabinet foot or a caster, and it is measured in newtons. Uniform load is force spread across the panel surface, measured in newtons per square meter. The same panel can carry a high uniform load and still flex under one heavy point, because that point creates a much higher local stress.
A：FS2000 is the top tier in the FS662–FS2000 range. It states concentrated load ≥8900 N, uniform load ≥46000 N/m², ultimate load ≥26700 N, impact load ≥1340 N, and rolling load of 8900 N over 10 cycles and 7120 N over 10,000 cycles. It represents the highest load set in the ladder rather than one single figure.
A：Because the two loads stress the panel in different ways. A spread load distributes force across the whole surface, so no single spot carries a spike, and the panel resists it as a plate. A point load concentrates force on a small area and creates a sharp local peak. Each case is rated separately, so the uniform figure is usually much larger in absolute numbers.
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