2026/08/19
Is "500kg for 5000N" dangerous? What is the load-bearing capacity of raised access flooring? Explanation of "specified load" and "allowable load."
Raised Access Floor
When selecting raised access flooring, "load-bearing capacity" is one of the most important factors that must be checked.
In typical offices, 3000N products are standard, while 5000N products are often used in heavy-duty zones where server racks and heavy furniture are expected to be installed.
When it comes to load-bearing capacity, there's no doubt that a higher number indicates better performance.
However, one thing that is often overlooked is,
- The load-bearing capacity is determined differently for slabs and raised access floors.
The idea that "a 3000N product can support up to 300kg, and a 5000N product can support up to 500kg" is not accurate.
That's the point.
This time, we will explain the load-bearing capacity of raised access floors, incorporating the perspective of the Free Access Floor Industry Association.
First of all, how is the load-bearing capacity determined?
Scene from a static load test.The method for determining the load-bearing capacity of raised access flooring is specified by the "static load test" in JIS A 1450.
In the test, a concentrated load is applied to the Raised Access Floor using a 50mm diameter pressure bar (steel column).
If it's a 3000N product, apply a load of 3000N; if it's a 5000N product, apply a load of 5000N.
- Amount of deformation when a load is applied
- Residual deformation after the load is removed
The parameters are measured, and if each is within the specified value, it passes the test.
The load applied in this test is called the "specified load."
Generally, the values of 3000N and 5000N listed in product catalogs, etc., indicate this specified load.
It is important to note that this differs from the concept of uniformly distributed load, which is the load-bearing capacity of a slab.
*KYODO KY-TEC uses test results based on JIS A 1450.
However, not all Raised Access Floor products on the market have been tested under the same conditions.
Please be sure to check the specifications of each product individually.
Why is load-bearing capacity expressed in "N (Newtons)"?
While the weight of furniture and equipment is generally expressed in kilograms (kg), the load-bearing capacity of Raised Access Floor is expressed in Newtons (N).
This is because the performance evaluation of Raised Access Floor focuses on the "magnitude of the applied force" rather than the "mass."
A Newton (1N) is a unit of "force" defined as the force that produces an acceleration of 1 m/s² on an object with a mass of 1 kg. On Earth, the force (gravity) acting on a 1 kg object is approximately 9.8 N.
Working backwards, the mass required to generate 1N is approximately 0.102kg. In simple terms, this corresponds to approximately 306kg for a 3000N product and approximately 510kg for a 5000N product. However, these figures do not directly represent the "allowable load capacity."
The specified load is not equal to the allowable load.
In reality, the center of gravity of furniture can be uneven depending on the arrangement of stored items and equipment.
Furthermore, even greater uneven load distribution may occur during an earthquake.
Therefore, it is not advisable from a safety standpoint to install heavy objects at their maximum load capacity for extended periods.
Based on this approach, the Free Access Floor Industry Association recommends treating the value obtained by dividing the specified load by 1.5, taking a safety factor into consideration, as the "allowable load." (See Table 1)
It's not enough to simply exceed the values listed in the catalog; it's crucial to operate within the permissible load capacity range.
The test subject is the main unit of "Arisugata".
There's one more point I'd like to draw your attention to.
While static load testing is based on applying results from tests conducted on the weakest part of a product, the test subject is ultimately the "main unit," which represents the product's original shape.
At the scene,
- Edge processing at the wall
- Opening processing for equipment piping
• Special cutting process
These kinds of things may happen.
These pre-fabricated units and optional materials are not subject to JIS testing.
Generally, cutting or drilling reduces the strength of a material.
Therefore, it is important to check whether end reinforcements and appropriate support structures are in place.
It's important to note that just because you've adopted a 5000N product doesn't necessarily mean that 5000N performance will be guaranteed everywhere on site.
What is the actual load capacity?
The permissible load capacity described so far is the permissible value for point load applied by a 50mm diameter pressure bar (50φ) used in static load tests.
However, since the fixtures that are actually installed are supported by multiple legs, the load applied to the Raised Access Floor will vary depending on the number and arrangement of the legs.
Because each unit of the Raised Access Floor has an independent structure, the load acting on each unit differs depending on which unit the furniture legs are placed on.
For example, the load conditions on a unit change significantly depending on whether only one leg is placed on the unit or multiple legs are concentrated within it.
Furthermore, even with heavy objects, if there are many legs and the load is distributed, it may be possible to reduce the burden on each unit.
Therefore, when considering the actual load capacity, it is important to comprehensively check not only the specified load and allowable load capacity of the product, but also the weight of the fixture, the shape and number of legs, and the layout plan.
What about network floors?
KYODO KY-TEC's network floor meets the requirements for both 3000N and 5000N static load tests.
Furthermore, because the 600mm x 600mm units are divided into smaller sections by slits, the structure is designed to prevent loads from concentrating in specific areas.
Furthermore,
- Easily distributes load across the entire surface.
- Multiple legs are less likely to be concentrated in a single structural unit.
- The end members also use the same ultra-high-strength lightweight concrete as the main unit.
These features ensure high load-bearing capacity.
Summary
・3000N and 5000N indicate the "specified load" during static load testing.
In actual operation, it is important to use the "permissible load capacity" recommended by the Free Access Floor Industry Association as a guideline.
The permissible load capacity for the 3000N product is approximately 2000N, and for the 5000N product it is approximately 3300N.
Please note that end processing sections, opening processing sections, and optional materials are not included in the test.
Since test conditions may vary depending on the product, it is important to check the performance evaluation method.
