When it comes to impact-resistant plasterboards, the requirement is usually straightforward: A board that will withstand the incidental and everyday knocks and impacts expected in busy environments where people or specific equipment may cause dents and holes in the wall. Think hospital corridors, aged care facilities, school classrooms and daycare centres.

With different plasterboards offering impact resistance, it may be less simple to know which one to use for a specific application.

How are impact-resistant plasterboards different?

Typically, plasterboards made for high-impact areas feature a denser core and sometimes they have thicker liner paper (e.g. Trurock). The denser core is achieved by reducing the porosity of the gypsum formulation.

Siniat Impactshield and Trurock are specifically designed to provide impact resistance. Trurock HD takes this one step further with a glass fibre mesh embedded in the core for superior impact resistance.

Other speciality boards like Fireshield, Soundshield and Multishield may provide better impact resistance than standard boards (e.g. Mastashield or Watershield), but they are not tailored for impact resistance. Therefore, Impactshield and Trurock are recommended for areas where impact resistance is a key consideration.

Soft and hard body impact

The key to understanding impact resistance is knowing the different types of impact: soft body, small hard body and large hard body (abuse resistance).

Soft body impact performance is largely influenced by the performance of the complete wall system, including framing, fixings and board configuration. Small hard body impact performance is more closely related to the plasterboard product itself, particularly its density. Similarly, large hard body impact resistance is related to board thickness, core density and reinforcement.

Soft body impact

A soft body impact represents a person or large object hitting the wall. A person falling against a wall, someone being pushed into a wall or a large padded trolley striking a partition are typical examples.

Because the impacting object is relatively large and yielding, the force is spread over a bigger area. Soft body impact can typically lead to the cracking of joints, flexing of the wall, failure of fixings and framing connections and large dents.

Hard body impact

A hard body impact simulates a small, rigid object striking the wall. In this instance, the force is spread over a smaller area, resulting in more concentrated, penetrating damage. Examples include a hospital trolley hitting a wall, a door handle slamming into a wall, and direct impacts from sports equipment, tools, or furniture.

Typically, hard body impacts can result in punctures, chips, deep (but smaller) dents and localised crushing of the gypsum core.

Large hard body impact (abuse)

Most impacts are incidental and unintentional. It is uncommon for a wall lining to be subjected to deliberate damage, such as that caused by tools or forceful kicks.

Deliberate actions, including punching or kicking a wall, or striking it with an implement, are classified as large hard body impacts.

When a wall is subjected to sufficient force, some visible damage is inevitable. Therefore, the objective of this criterion is not to eliminate damage entirely, but to prevent penetration or breakthrough of the wall lining.

Continuous glass fibre mesh embedded within the board provides excellent resistance to penetration and breakthrough (e.g. Trurock HD). An additional benefit is that damaged areas can often be repaired simply by applying a plaster compound, rather than replacing the entire board.

Because the glass fibre mesh generally remains intact, repairs made with plaster compound retain most of the wall's original strength. Only exceptionally high-energy impacts are likely to compromise the mesh and require more extensive remediation.

Testing for impact resistance

For plasterboard and lightweight wall systems, the NCC 2022 Specification 6 – Structural tests for lightweight construction requires three key performance tests that together assess robustness. It’s important to note that Specification 6 is written around the performance of a wall system of lightweight construction, not individual products.

Soft body impact test

Soft body impact tests are intended to simulate the effect of a person falling or colliding with a wall and assess the wall system's ability to withstand accidental impact without suffering unacceptable damage or loss of structural integrity.

Method:

The test consists of a dynamic impact by an impact bag released from the prescribed height, with compliance assessed against the relevant damage and deflection criteria.

The impact severity depends on the wall location:

350mm drop height for certain Class 9b public areas.
150mm drop height for shafts and fire-isolated exits.
100mm drop height for general fire rated walls

Surface indentation test

This test measures dent resistance of the wall lining surface rather than structural impact resistance and simulates localised damage from trolleys, wheelchairs, luggage, equipment, or concentrated knocks.

Method:

The test method consists of a 10mm steel ball pressed into the wall surface with a force of approximately 150 N applied for a specified time.

Static pressure test

This is not strictly an impact test, but it forms part of the NCC robustness assessment. The purpose is to test for crowd pressure, leaning loads and general service loads on walls.

Method:

The following loads are applied to the wall, depending on their location:

kPa for certain high-occupancy Class 9b areas such as stadiums.
0.35 kPa for shafts and fire-isolated exits.
0.25 kPa for general fire rated walls

Hard Body Impact Test

The NCC Specification 6 tests do not include a formal hard body impact test, but Siniat subjects its impact resistant boards to rigorous independent testing by BRANZ to test the serviceability of the wall under a range of impact energies. Other than the Specification 6 tests, this test evaluates the performance of the board in isolation.

Method:

Small hard body impact resistance is measured by dropping a 50mm steel ball weighing 510 grams from various heights onto the board to simulate the concentrated, high-velocity impacts typical of a busy commercial environment.

Indentation depth is measured to determine its performance. Small hard body impact resistance is closely related to plasterboard density.

So, how do I choose the right board?

1. Categorise the environment

A common mistake is specifying only the board. Impact performance depends on a variety of factors and elements in the wall system including the board type, thickness, number of layers, stud spacing and backing materials.

For instance, a 13mm impact-resistant board on 64mm studs at 600mm centres may achieve one level of performance. The same board on 92mm studs at 450mm centres may achieve a different performance.

However, where impact resistance is critical, hard body impact performance can be a useful differentiator between products because it measures the board's ability to resist localised damage such as dents, punctures and core crushing from concentrated impacts.

The best way to choose the right impact-resistant wall system, and ultimately the board, is to start by evaluating the type and severity of impacts expected in the space.

Low impact areas like offices, apartments and hotel rooms may be exposed to occasional knocks from furniture and general wear and tear. Standard 13mm plasterboard like Mastashield, Watershield or standard fire-rated plasterboard like Fireshield will usually be sufficient.
Medium impact areas like school classrooms, hospital wards and hotel corridors may be damaged by chairs, trolleys or wheelchairs. Consider using an impact-resistant board like Impactshield or Trurock.
High impact areas like school corridors, hospital corridors and airports may be exposed to repeated knocks from baggage carts, hospital beds and trolleys. For this type of application Trurock is best.
Areas at risk of abuse like hospital waiting rooms, specialist care facilities or public toilets that can experience occasional intentional damage would benefit from the continuous glass fibre reinforcing mesh in Trurock HD. This generally allows an easy repair with plastering compound instead of replacing the sheet.
Severe impact/ abuse areas such as detention centres and mental health facilities, which are at high risk of sustained intentional damage need a hard surface board like Trurock backed by steel sheet or plywood, combined with closer stud centres.

2. Consider other requirements

Impact resistance is often not the only consideration when choosing the right plasterboard – other requirements may also come into play. Is the board required to be water and mould resistant as well? Does the wall system require a fire rating? What are the acoustic requirements?

It’s worth noting that all impact-resistant boards have a higher acoustic performance than other boards due to the denser core.

Conclusion

Choosing the right impact-resistant plasterboard starts with understanding how the space will be used and the type of impacts the wall is likely to experience. While NCC testing assesses the performance of the complete wall system, product-specific testing can help differentiate boards and their ability to resist dents, punctures and everyday damage.

By considering the expected impact level alongside fire, acoustic and moisture requirements, you can select a wall system that delivers the right balance of durability, compliance and value.

For more information and guidance in choosing the right impact-resistant board, contact the Siniat Technical Team.

Architecture & Design Team

Siniat

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