Oaktree Developments in West Yorkshire used Regupol E48, a recycled tyre crumb product from CMS Acoustics to achieve Part E compliance

Part E compliance, material cost and project sustainability are all high on the construction agenda, but developers should exercise particular caution when evaluating the relative importance of each factor. With climate change under the spotlight and the new Code for Sustainable Homes now in place, developers are increasingly accountable to build housing that is more environmentally sound.

In a construction industry that is highly cost-driven, it is not surprising that a number of low-end, often poorer performing acoustic flooring materials have entered the market. Although these products appear more favourable on budget sheets, by and large, the compounds used to manufacture these systems have a major and negative impact upon the environment.

As such, a better understanding of which materials and compounds are safer for the environment will ultimately help secure long term sustainability and offer savings far greater than cost.

The true cost of low-end material
Although low-end acoustic flooring materials are cheaper than higher-end systems which incorporate cork, rubber and polyurethane (PUR), their long term sustainability and the manufacturing methods that have been involved in their construction can have a long term environmental detriment.

The effects of low-end acoustic flooring systems upon the environment start with the manufacturing process, with many unable to state ‘zero ODP’ (Ozone Depletion Potential). Substances with ODP degrade when they eventually reach the upper segment of the atmosphere (the stratosphere) and harm the ozone which acts as a filter for UVB radiation.

Furthermore, many lower-end products do not have ‘zero GWP’ (Global Warming Potential). GWPs measure the influence that greenhouse gases have on the Earth’s natural temperature, including the ability for gas molecules to absorb or trap heat, and the length of time they remain in the atmosphere before being removed or broken down. The GWP methodology allows the contribution that each greenhouse gas makes towards global warming to be assessed.

Developers should also be aware of what qualifies a product as recycled. Some manufacturers claim scrap materials that are reused in the production process constitute postindustrial waste, when this is not the case.

Whilst reusing scrap material is good environmental practice, since it minimises the amount of waste from the plant, it does not strictly qualify as recycled content. A manufacturer can only state its products are made from recycled matter when the materials have been recovered or diverted from the solid waste stream, either at postconsumer or post-industrial level.

The sustainability factor
Thinking carefully about the environmental impact of product manufacture is only half the battle, as the longevity of the product must also be addressed.

Quite often, the lifespan of some lower-end systems is relatively poor compared to those at the higher end. The former may meet the necessary acoustic requirements in the first instance, but some materials have been known to either ‘bottom out’ or stiffen significantly once loads are applied to floor surfaces. The implication of this is that the required acoustic performance can no longer be achieved. In some instances the developer may be called back in to rectify the problem, and consequently incur high remedial costs.

When considering these factors simultaneously, the initial higher cost of eco-friendly materials is offset by longer term performance and sustainability.

Taking the eco-friendly route
To protect the environment and achieve long term product durability, there are a number of eco-friendly and hardwearing acoustic flooring products available for both under-screed and resilient layer applications.

For screed isolation, best practice is to use acoustic flooring treatments that are manufactured from recycled rubber materials. Comprising post-consumer shredded and cleaned styrene butadiene
(SBR) tyre rubber and post-industrial ethyl propylene dione monomer (EPDM) that is bound with a polyurethane-based binder, the manufacturing process is energy efficient and creates minimal waste.

The actual recycled content in recycled rubber treatments is relatively high, ranging anywhere from 30 to 90%. Recycled rubber crumb compounds, for example, are highly durable whilst remaining entirely recyclable. They will not rot or break down over time and their physical properties will not alter.

When selecting an acoustic underlay treatment, it is recommended that a PUR foam/cork compound is chosen. Not only is this combination proven to deliver higher levels of performance than lower end rubber/cork combinations, it also removes the risk of plasticizer migration – a common problem experienced when rubber/cork compounds are used beneath certain floor finishes, such as vinyls and carpets. Furthermore, environmental benefits are not compromised when using PUR foam/cork composites, as the foam content can be re-ground and recycled.

Providing they are installed in accordance with manufacturer guidelines, acoustic solutions as described above should last the lifetime of the building in which they are installed.

Investing in the future
Although low-end acoustic materials appear more cost-effective at the outset, their potential long term costs must also be fastidiously assessed.

Taking the eco-friendly route by selecting more sustainable treatments may require a slightly greater outlay, but the cost saving for the environment and the benefits of long term performance far outweigh the initial impact on spend.

Paul Absolon is technical director for CMS Acoustics.

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