TL;DR
- Shore A hardness measures the resistance of rubber and elastomers to indentation, tested under BS EN ISO 868.
- Typical commercial rubber gym tiles range from 55 to 75 Shore A, balancing shock absorption and stability.
- Lower Shore A values (55-60) offer greater force reduction for functional training and acoustic attenuation.
- Higher Shore A values (70-80+) provide necessary point-load resistance for heavy free weights and Olympic lifting platforms.
- Specifying the incorrect hardness can lead to premature flooring failure, equipment damage, or inadequate acoustic isolation.
Understanding the Shore A Scale
Shore hardness is a measure of the resistance of a material to indentation. The Shore A scale is specifically designed for softer, flexible materials such as rubber, elastomers, and softer plastics. The scale runs from 0 to 100, where higher numbers indicate a harder material with greater resistance to indentation.
In the context of commercial gym flooring, Shore A hardness is a primary indicator of how the surface will respond to dynamic loads, such as dropped weights, and static loads, such as heavy fitness equipment. It directly influences the floor's force reduction capabilities, acoustic performance, and long-term durability.
Selecting the appropriate Shore A hardness requires a precise understanding of the intended application. A surface that is too soft may compress excessively under heavy loads, leading to instability for users and potential damage to the subfloor. Conversely, a surface that is too hard will fail to absorb impact energy, increasing the risk of equipment bounce and acoustic transmission.
Testing Methodology: BS EN ISO 868
The standard method for determining the indentation hardness of plastics and ebonite, including rubber gym flooring, is BS EN ISO 868. This standard specifies the use of a durometer, an instrument that measures the penetration of a specified indentor into the material under defined conditions.
The test involves applying the durometer to the surface of the material and reading the hardness value. For the Shore A scale, the indentor is a hardened steel rod with a truncated cone shape. The applied force is carefully controlled, and the reading is typically taken after a specified duration, often 15 seconds, to account for the viscoelastic nature of rubber.
| Standard | Title | Application |
|---|---|---|
| BS EN ISO 868 | Plastics and ebonite — Determination of indentation hardness by means of a durometer (Shore hardness) | Primary test method for determining Shore A hardness of rubber gym flooring. |
| BS EN ISO 24343-1 | Resilient and laminate floor coverings — Determination of indentation and residual indentation | Used to assess the recovery of the flooring after a static load is removed. |
It is essential that specifiers request test data conducted in accordance with BS EN ISO 868 to ensure accurate and comparable hardness values.
The Relationship Between Hardness, Density, and Thickness
While Shore A hardness is a critical metric, it does not operate in isolation. The overall performance of a rubber gym floor is determined by the interplay of hardness, density, and thickness.
Density, typically measured in kilograms per cubic metre (kg/m³), refers to the mass of the material per unit volume. Higher density rubber generally exhibits greater durability and resistance to wear. However, two rubber tiles with the same density can have different Shore A hardness values depending on the specific formulation and manufacturing process.
Thickness is equally important. A 15mm tile with a Shore A hardness of 65 will perform differently than a 30mm tile with the same hardness. Thicker tiles provide greater capacity for impact absorption and acoustic attenuation, even if the surface hardness remains constant.
When specifying gym flooring, it is necessary to consider all three variables to achieve the desired performance characteristics. For example, heavy free-weight areas require high thickness for impact absorption, combined with a moderate to high Shore A hardness to prevent excessive compression and ensure stability.
Matching Shore A Hardness to Gym Zones
The diverse activities within a modern commercial gym necessitate a zoned approach to flooring specification. Different zones require specific Shore A hardness profiles to optimise performance and safety.
Free Weights and Olympic Lifting
Areas dedicated to heavy free weights and Olympic lifting experience the most severe impact loads. Dropped dumbbells and loaded barbells generate significant kinetic energy that must be absorbed by the floor to protect the subfloor and minimise acoustic transmission.
For these zones, a Shore A hardness of 65 to 75 is typically recommended. This range provides sufficient firmness to support heavy static loads (such as weight racks) and ensure user stability during lifts, while still offering the necessary compliance to absorb impact energy. Specialist lifting platforms may incorporate high-density rubber inserts with a Shore A hardness of 80 or above to provide a highly stable surface for maximum power transfer.
Functional Training and CrossFit
Functional training zones, including CrossFit areas, require a versatile surface that can accommodate a wide range of activities, from plyometrics and sled pushes to kettlebell swings and moderate weightlifting.
A Shore A hardness of 60 to 70 is generally suitable for these applications. This provides a balance of shock absorption for dynamic movements and sufficient firmness to support equipment and prevent excessive fatigue during repetitive exercises.
Cardio and Machine Zones
Cardio zones, housing treadmills, cross-trainers, and resistance machines, primarily require a surface that provides stability, slip resistance, and acoustic isolation from structure-borne noise.
A Shore A hardness of 65 to 75 is appropriate for these areas. The firmer surface ensures that heavy machines remain stable and do not compress the flooring excessively, which could lead to uneven wear or alignment issues.
Studios and Mind-Body Spaces
Studios dedicated to yoga, Pilates, and low-impact group exercise require a softer surface that provides comfort for floor-based activities and reduces fatigue during prolonged standing.
A Shore A hardness of 55 to 65 is ideal for these spaces. This softer profile offers greater compliance and comfort, enhancing the user experience for activities that do not involve heavy impact loads.
Impact on Acoustic Performance
Acoustic control is a critical consideration in gym design, particularly in mixed-use developments or multi-storey buildings. The Shore A hardness of the flooring plays a significant role in mitigating both airborne and impact sound transmission.
Impact sound, generated by dropped weights or footfall, is transmitted through the building structure. Softer rubber flooring (lower Shore A hardness) generally provides better impact sound insulation (measured as ΔLw in accordance with BS EN ISO 717-2) because it compresses more readily, absorbing the kinetic energy and reducing the force transmitted to the subfloor.
However, specifying a floor that is too soft can compromise stability and durability. Therefore, acoustic performance must be balanced against the mechanical requirements of the space. In highly sensitive environments, such as upper-storey gyms, a multi-layered acoustic system may be required. These systems typically combine a softer, highly resilient underlay (e.g., 50-55 Shore A) with a firmer, more durable surface layer (e.g., 65-70 Shore A) to achieve optimal acoustic isolation without sacrificing performance.
Point-Load Resistance and Indentation
Point-load resistance is the ability of the flooring to withstand concentrated static loads without suffering permanent deformation. This is particularly relevant in areas with heavy equipment, such as weight racks, multi-gyms, and cardio machines.
The Shore A hardness is a strong indicator of point-load resistance. Harder materials (higher Shore A values) are less susceptible to indentation. When a heavy load is applied to a soft rubber floor, the material compresses. If the load exceeds the material's elastic limit, or if it is applied for an extended period, the floor may suffer residual indentation, failing to return to its original thickness.
This is assessed using BS EN ISO 24343-1, which measures the residual indentation after a specified static load is removed. For areas with heavy static loads, specifying a flooring with a higher Shore A hardness (70+) and excellent recovery characteristics is essential to prevent permanent damage and maintain a level surface.
Specifying for Multi-Use Spaces
In many commercial gyms, space constraints necessitate multi-use zones where a single flooring solution must accommodate a variety of activities. Specifying for these areas requires a careful compromise.
A Shore A hardness of 65 is often considered the optimal middle ground for multi-use spaces. It provides sufficient firmness for moderate weightlifting and equipment stability, while offering adequate shock absorption for functional training and group exercise.
When specifying for multi-use areas, it is also crucial to consider the force reduction requirements outlined in BS EN 14904:2006. While this standard is primarily designed for indoor multi-sports surfaces, the principles of force reduction are applicable to gym environments. A surface with a Shore A hardness of 65, combined with appropriate thickness, can achieve the necessary force reduction to protect users from impact-related injuries while maintaining versatility.
Key Takeaways
- Specify Shore A hardness based on the specific activities and loads within each gym zone.
- Ensure hardness values are derived from testing in accordance with BS EN ISO 868.
- Balance acoustic requirements (favouring lower Shore A) with point-load resistance and stability (favouring higher Shore A).
- Consider the interplay of hardness, density, and thickness to achieve optimal performance.
- For multi-use spaces, a Shore A hardness of approximately 65 offers a versatile compromise.
FAQ
There is no single ideal hardness. It depends on the zone. Free weights require 65-75 Shore A, while studios benefit from a softer 55-65 Shore A.
Generally, softer rubber (lower Shore A) provides better impact sound insulation by absorbing more kinetic energy. However, this must be balanced against the need for stability under heavy loads.
Yes. A floor with a very high Shore A hardness (e.g., 85+) will fail to absorb impact energy, increasing the risk of equipment bounce, acoustic transmission, and user discomfort.
Flooring with a very low Shore A hardness (e.g., <55) in a heavy weight area will compress excessively, causing instability for users, potential damage to the subfloor, and permanent indentation from equipment.
No. Hardness measures resistance to indentation, while density measures mass per unit volume. Two tiles can have the same density but different hardness values based on their formulation.
It is tested using a durometer in accordance with BS EN ISO 868, which measures the penetration of a specified indentor into the material.
Thickness does not change the inherent hardness of the material, but it does affect the overall performance. A thicker tile of the same hardness will provide greater impact absorption.
CrossFit requires a versatile surface. A Shore A hardness of 60-70 provides a good balance of shock absorption for dynamic movements and stability for weightlifting.
For areas with heavy static loads, such as weight racks, specify a higher Shore A hardness (70+) to ensure adequate point-load resistance and prevent permanent indentation.
While possible, it is not optimal. A zoned approach, matching hardness to specific activities, ensures better performance, safety, and longevity of the flooring.
Related Resources
- How to specify gym flooring
- Acoustic testing in commercial gyms
- Rubber vs vinyl gym flooring
- Upper storey gyms: acoustic challenges
- Zone planning for commercial gyms
Specification Summary Product: Superstrata Rubber Gym Flooring Material: Recycled SBR rubber with EPDM colour granules, polyurethane bound. Hardness: [Insert required Shore A hardness, e.g., 65 Shore A], tested to BS EN ISO 868. Thickness: [Insert required thickness, e.g., 30mm]. Density: [Insert required density, e.g., 950 kg/m³]. Fire Rating: Class Efl to BS EN 13501-1 (or higher if specified). Slip Resistance: PTV ≥36 (low slip potential) to BS 7976-2. Installation: Fully bonded to prepared subfloor in accordance with BS 8203 and manufacturer's instructions.