Achieving a Good Separation Floor
In this article we will look at some commonly held myths surrounding the contracting world concerning thermal and acoustic insulation, condensation control, fire protection, and ground gas protection. In this article, we ask the question, is it true that a concrete floor is the only way to achieve a good separation floor? When seeking to manage the impact of sound within buildings effectively, a misconception is that you can’t achieve good acoustics with a lightweight floor, leading to the preconceived belief that a concrete floor is the best way to address the acoustic challenge. There are two types of sounds to be considered in addressing the challenge of achieving the best acoustic solutions in building design: airborne sound and impact sound. Airborne sound is generated by the source vibrating the air to create sound waves. When these waves strike the walls, roof, or floors, they are converted into vibrations in the structure, which transfers the sound around the building. This sound is then re-emitted by other surfaces in the same way as a speaker generates sounds. Airborne sound can originate from outside the building and within and typically travels throughout the structure. Building regulations require most building elements to have some degree of airborne sound resistance built in. Impact sound occurs when mechanical impacts directly cause vibrations in the structure rather than via an external sound wave. These vibrations pass throughout the structure before being re-emitted in other areas, like airborne sound. Unlike airborne sound, however, the regulations regarding impact sound are typically only concerned with sound transmission between the separating floors of a building.
The heavyweight challenge
When considering acoustics, the mass of a wall or floor is a significant factor. The heavier the element is, the harder it is for incoming soundwaves to induce any vibrations. This reflects a greater proportion of the incident sound waves, resulting in less sound being transferred into the structure. In most cases, it is correct to say that heavy elements such as brick walls or concrete floor slabs are better able to restrict the passage of sound than lighter timber frame structures. However, it is not always practical or economically viable to use high mass constructions. This is particularly true in refurbishment projects where increasing the mass is often impossible. Lightweight flooring systems can often provide the most effective solution in modern building design and refurbishment. Timber floors have also become more popular for their sustainability benefits over traditional concrete. The speed of installing a lightweight floor without the additional need for wet trades and associated drying out period can be another critical factor. Solutions for managing the sound transmission and acoustics of a lightweight flooring system will consider the aspects of isolation and absorbency at the design stage.
An effective way to prevent sound transmission through structures is by physically isolating one side from the other. This can be achieved by using entirely separate structural elements, such as independent floor and ceiling joists or resilient mountings for floor and ceiling surfaces. The aim is to break the pathway for sound to travel through the structure from one side to the other. With independent structures, there is an actual discontinuity in the pathway, leading to the best acoustic performance. However, this approach results in very thick wall or floor elements, so it is not always practical.
Resilient layers are usually a cheaper, thinner, and lighter weight solution. They can be applied as floor deck or batten systems, ceiling mounting bars, or both. These work similarly to car suspension by damping the vibrations and reducing the energy from the sound waves by allowing a degree of movement. These systems must be matched to the expected loadings on floors, as heavy weights can damage the resilient layer and reduce effectiveness.
Absorbent acoustic materials are important in reducing the echoes within cavities in a wall or floor construction. The desired effect is breaking up the sound waves in these spaces. As a result, it reduces the overall energy transfer by converting the energy in the sound waves into heat due to friction between adjacent fibres. Fibrous materials such as mineral or polyester quilts are usually used for this purpose, most commonly in timber or steel-framed structures. If voids are present, partially filling them with an absorbent material will generally help reduce the sound transfer.
Acoustic Floor Systems
Batten systems such as Profloor Dynamic battens are popular in new build timber frame floors and are the top-performing floating floor system. The extra depth introduced between the battens simplifies service runs within the floor and provides additional void space in which additional fibre layers can be added to boost sound absorbency. The downside to batten systems is that they tend to be deeper, so it may not be practical to apply them to all floors when tying into adjacent floor levels is an issue.
Deck systems are much shallower and can boost the impact sound performance of a floor. However, they offer little scope to improve airborne performance. For that reason, they tend to be used on concrete floors where the base floor mass does most of the work dealing with airborne noise transfer. Deck systems are also ideal for refurbishment projects where floor to ceiling height may limit the scope for using a batten system. Systems like the Profloor Microdeck at only 17mm can improve impact performance noticeably while having minimal impact on floor levels, services and internal trim and skirting.
Levelling systems allow a floor to be raised and levelled while introducing a level of acoustic performance. This is useful in existing buildings where the floor may be substantially out of level or in a new build where pre-stressed slabs may be used, which have an inbuilt camber that must be corrected to give a smooth level finished floor. Using a dry system, rather than a screed allows for a quicker installation period. We supply a comprehensive portfolio of batten systems, overlay deck systems and levelling systems to cover a range of project requirements and floor types.