These are frequently asked questions that have been posed to us by our customers. To
make it easier to find what you are looking for, we have grouped them for you under the
following headers:
What is the difference between NRC and CAC?
Noise Reduction Coefficient (NRC) refers to the average amount of sound an acoustic product can absorb, and therefore how much quieter that product can make a space. NRC is measured on a scale that ranges from 0 to 1. An NRC of 0 means that the product absorbs no sound, e.g. a concrete floor, and an NRC of 1 means that the product absorbs all sound. It follows therefore that the higher the product’s NRC, the better it will be at absorbing the sound.

A product’s Ceiling Attenuation Class (CAC) indicates the ceiling’s ability to prevent airborne sound from traveling between adjacent rooms when the dividing wall does not connect with the structural ceiling. A CAC will range between 0 to 45 for ceiling panels. Ceiling panels that have high CAC ratings (30 or greater) and are good at blocking sound from ceiling equipment may not necessarily have a high NRC performance and may not necessarily maintain quality sound absorption.

What does a STC rating measure?
The Sound Transmission Class (STC) is measured to calculate the effectiveness of soundproofing materials in reducing sound transmission between rooms. Simply put, the STC is the decibel (dB) reduction a product provides and is used to measure how much sound will an acoustic panel will block from getting through to the other side. The higher the STC rating, the more effective that material is at reducing sound transmission of the most common frequencies.
Why is the AC important?
The Articulation Class (AC) classifies suspended ceilings according to their ability to contribute to acoustic privacy in an open plan office setting. The AC can be used as a tool to classify and compare acoustic ceiling systems. A high classification will improve privacy between neighbouring work stations. AC values of 170 or greater are generally recommended in open plan office settings.
How does the NIC rating differ from other acoustic measurements?
The Noise Isolation Class (NIC) is a measure of the total sound insulation performance between two rooms after construction is complete. The NIC differs from the CAC, STC and NRC ratings in that it is a field measurement. The NIC all sound paths through walls, doors, windows, and penetrations into account and best represents what people will actually experience in the space. Higher values indicate higher levels of sound insulation between rooms, NIC values of 35, 40 or 45 are typical in normal applications.
Fire Performance
How does stone wool react to fire?
Stone wool is at the core of all Rockfon products. It is made from basalt rock and is by nature non-combustible. The melt point of stone wool is in excess of 1,000°C.
What is measured when testing to the EN 13501-1 standard?
The EU Reaction to Fire evaluation criteria (EN 13501-1) measures:
- a material’s ignitability,
- the rate of heat release,
- the rate of spread of flame,
- the rate of smoke emission,
- the toxic gas emission,
- the presence of flaming droplets/particles and/or a combination of these safety

The highest classification a product can achieve under EN 13501-1 is A1. Products with an A1 classification do not contribute to the development and spread of fire. They generate neither smoke nor flaming droplets. Most Rockfon ceilings have an A1 rating.

Why is a product’s fire resistance response important?
Fire resistance indicates how well a building element can hold back fire and contribute to preventing it from moving from one room to another for a stated period of time.

Three criteria are measured:
R: Load bearing capacity
E: Integrity
I: Insulation

The inherent properties of stone wool ensure that fire-resistant Rockfon ceiling tiles provide excellent protection in the event of a fire.

Seismic design
Do ceiling systems in Australia need to be assessed for seismic design?
Earthquake forces must to be considered for designing all suspended ceilings in Australia. The design must comply to AS/NZS 2785:2000 – Suspended Ceilings, Design & Installation. This will generally be undertaken by the project's structural engineer who may in turn call for the involvement of qualified engineers more familiar with seismic design.

The three main standards pertaining to suspended ceilings in Australia are:
- AS1170.4:2007 - Structural Design Actions – Earthquake Actions in Australia
- AS/NZS 1170.0.2002 – Structural Design Actions – General Principals
- AS/NZS 2785:2000 – Suspended Ceilings, Design and Installation

Indoor Air Quality
How do Rockfon products contribute to indoor air quality?
Ceiling materials with low emission levels, that naturally resist mould and starve microorganisms contribute to improved indoor air quality (IAQ). The entire Rockfon ceiling tile and panel range of stone wool products is GREENGUARD Gold Certified by the United States Green Building Council (USGBC) for low emissions.
Can Rockfon ceiling tiles aid the building certification process?
The USGBC LEED building certification process is designed to inspire innovative solutions that support healthy, highly efficient and cost-effective green buildings during the design, construction, operation and maintenance process. Rockfon acoustic ceilings are the perfect choice for sustainable buildings when pursuing LEED v4 points for building interiors.
Cleaning and Hygiene
Can you clean a Rockfon ceiling tile?
All Rockfon ceilings can be cleaned with a vacuum cleaner fitted with a soft brush attachment. Tiles that have a micro-textured surface can also be cleaned using a damp cloth or sponge.

The Rockfon MediCare range of healthcare ceiling tile products have a durable, highly water-repellent surface that resists diluted solutions of ammonia, chlorine, quaternary ammonium and hydrogen peroxide. They can also be disinfected periodically following a steam cleaning protocol defined by experts and using an adapted surface mop.

Does stone wool provide sustenance for micro-organisms?
Rockfon ceiling tiles are made from water-repellent stone wool. They are tested in accordance with JIS Z 2801:2000, ASTM C 1338-96 and NFS 90-351:2013 and provide no sustenance to the following microorganisms:

- Escherichia coli
- Staphylococcus aureus
- Methicillinresistent staphylococcus aureus (MRSA)
- Stachybotrys chartarum
- Penicillium brevicumpactum
- Alternaria tenuissima
- Aspergillus Brasiliensis
- Sporobolomyces roseum
- Rhodotorula rubra

The Rockfon MediCare range are designed to meet the requirements of zones with different levels of infection risk in healthcare facilities. The products all meet low particle emission requirements and have a clean room classification of ISO Class 5 or better (ISO 14644-1).

Humidity and Sag Resistance
Do Rockfon products absorb water?
Stone wool is by nature a hydrophobic material.
This means it does not absorb water and nor hold moisture. This makes our stone wool ceiling panels and tiles humidity-resistant and allows them to remain dimensionally stable even up to 100% relative humidity (RH), and in temperatures from as low as 0°C to as high as 40°C.
Will the tiles sag in humid conditions?
Huumidity can weaken the structure of some acoustic ceiling tiles, causing them to sag and droop beneath their ceiling suspension system. In extreme cases, sagging ceiling tiles may even fall from their grid entirely. This generally occurs in buildings under construction before the building is temperature and humidity-controlled, or prior to the installed materials drying out appropriately.

Stone wool ceiling panels can be installed in the early stages of construction, when the windows are not fully sealed, without any risk of sagging. The moisture resistant characteristics of stone wool acoustic ceiling tiles means they will remain unaltered throughout the building’s lifecycle, maintaining their shape and physical characteristics.

Rockfon stone wool ceiling panels do not warp, curl or cup. They will not rot, and nor will they corrode. In fact, with virtually no organic content, they are naturally resistant to the issues associated with mould, mildew and microorganisms. Even in consistently ”wet” areas like kitchens, restrooms and leisure centres, the product will not sag.

Can the products be recycled?
The Rockfon business model incorporates circular economy thinking. In many instances, waste materials are upcycled, our own waste is recycled in closed loops and the products are designed for a long life.

One of the most valuable features of stone wool is that it can be made with materials that would otherwise be landfilled or downcycled. Overall, around one-third of our raw materials consist of repurposed waste from metals manufacturing, power plants and wastewater treatment. We can upcycle slag from the metal industry and sludge from water treatment plants for example, and even in small amounts old ceramics like broken bathroom sinks and toilets.

What does “design for disassembly” mean?
Rockfon as a business focuses on a key aspect of the circular economy that is referred to as “design for disassembly”. In order for products to be recycled they must be easy to take apart and separate into different materials.

Using building materials that are modular and easy to dismantle also make it possible to reuse them when making changes to spaces, rather than having to dispose of them.

Certifications and Labels
What is an EDP?
An Environmental Product Declaration (EPD) is an independently verified and registered document that communicates transparent and comparable information about the life-cycle environmental impact of products. It is a voluntary declaration of the life-cycle environmental impact of a product.
How does an EDP aid in the building certification and verification process?
Rockfon’s EPDs clearly communicate and document the environmental performance of the products.

The impact on the environment is considered by calculating the effect of a product from ‘cradle-to-gate’. In other words, it must account for upstream environmental impact (the raw material resourcing/extraction and their transportation to the manufacturing facility) and the impact of the production itself.

In order to communicate the environmental profile of Rockfon products, the company has taken steps to simplified their EPDs. You will now be able to find two EPDs; one for its high- density products and a second for its low-density products.

By using Rockfon specific EPDs, which are independently verified, a customer can achieve maximum credits in their LEED®, BREEAM® or DGNB® building certification efforts. The transparency and consistency of the Rockfon EPDs, according to the EN15804 standard, allows the customers to use the results and calculate the building’s life cycle assessment (LCA) that is required to gain elite-level certifications.