There’s more to delivering the right level of acoustic performance through wall partitioning systems than meets the eye. Andrew Richardson, Technical Manager with Fermacell, takes a look at what needs to be considered from specification through to installation.
Airborne sound insulation is the ability of material separating two rooms to minimise the passage of sound through the dividing elements and its surrounding structure. The materials are assessed in a sound reduction index by relating the sound power reduction through the material itself, typically expressed as an Rw figure.
The approved Document E is guidance to acoustic performance for houses, flats, schools, hotels and hostel types of accommodation. Whether new build, or perhaps a material change of use, all projects have different criteria to improve the sound insulation and privacy between domestic and residential rooms.
There are several ways of approaching compliance, primarily with the design of separating walls and floors that will meet and exceed the requirements in the guidance document. The onus is therefore on the installer to ensure good on site workmanship and careful consideration must be given to the prevention of flanking transmission around the installed systems.
As Part E sets out a requirement for 10% pre-completion site testing of each different type of separating (party) walls and floors, this puts the onus onto the builder to prove, by site testing, that the sound insulation meets the requirement of the new regulations.
Good acoustics is typically down to the mass of the wall and good detailing. Fermacell is particularly suitable for acoustic solutions as it’s a ‘one-board type’ solution for partitions, wall linings, ceilings and even as an acoustic dried screed system. This reduces the possibility of mix and match, a common issue effecting performance.
Greater mass means that Fermacell systems are generally thinner than traditional ones and, where floor space is at a premium, we can design more floor space back into the internal area without the need to compromise on performance.
Where two boards are required, the boards can be fixed to each other, thereby enhancing the overall performance by reducing the direct contact with the substructure.
The flexibility and acoustic properties of Fermacell were instrumental in it playing a small but significant role in the transformation of the Royal Shakespeare Theatre in Stratford-upon-Avon.
Alongside the new thrust stage auditorium being built, the new complex will include substantially expanded and fully accessible public areas including a rooftop restaurant, a riverside café and three bars, as well as a new colonnade linking the Royal Shakespeare and Swan Theatres for the first time.
Architects, Bennetts Associates, in conjunction with Acoustic Dimensions, looked closely at the acoustic needs of the Theatre and specified Fermacell for many of the internal walls. These include front of house zones, the ‘void’ foyer between the existing building and new theatre, a number of dressing room areas and the toilets.
Fireclad Limited has been installing the Fermacell board, using 12.5mm Fermacell in combinations of either two or four layers thick, depending on the acoustic requirements of the individual walls to ensure outside noise levels are kept to a minimum so as not to disturb the actors, or the enjoyment of the audience.
At ground floor level four skins of Fermacell have been used either side of the partitioning, and a similar thickness used for a number of the dressing rooms, training, study and rehearsal spaces located on other floors.
The auditorium itself has concrete walls, with a number of Fermacell infills. The two main corridor walls outside the drum of the auditorium are made of Fermacell board and separate the front of house area on the riverside elevation which contains an interval drinks zone and café.
Sound and light locks built of two partitions with two layers of Fermacell 12.5mm board to each side used on the fourth floor of the theatre where the dimmer room and workshop areas are contained.
In another project, around 20,000 square metres of 12.5mm Fermacell board has been used in the creation of the interior walls of the new £15m Northolt Leisure Centre in Ealing West London.
This includes the administration areas on the ground floor, the changing rooms and dance studios located on the first floor; and also in the community areas.
Keeping noise levels down between adjoining walls was key but so was using the mass of the board in a smaller footprint to give more space. Just one layer of 12.5mm board was needed, whereas conventional plasterboard would have required two.
Clearly specifying the right materials for the acoustic job to be done is only one half of the equation – link this with correct and simple detailing and you get a robust solution that really works.
For further information please visit: www.fermacelldrylining.co.uk
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