Mineral Wool Glass Fibrous Insulation
Acoustic Grade Insulation
Mineral wool, mineral fibre, mineral cotton, mineral fibre, man-made mineral fibre (MMMF), and man-made vitreous fiber (MMVF), is the general precise terminology used for labelling or describing fiber materials that are formed by spinning or drawing molten minerals to create a substance.
They are more commonly known to us under brand names like: Rockwool, Roxull, Rockinsul, Rocksul, CSR Rrockwool, Bradford Insulation, Tombo, Nichias, KCC to name the most popular. The most popular labeling term for this type of material is rockwool.
There are four diffined types of insulation all with their own characteristics and properties.
Thermal Insulation Grade is the most used material standard worldwide on the market. It's appropriate usage is for installing intro partitions, roofs and floors to keep homes warm (thermal retention). It also provides excellent fire protection and is used in fire rated partitions in offices and other building constructions.
The material works by trapping heat in air pockets found within the multitude of layers in the material itself. Thermal insulation densities start from 30kg density - 120kg density. Thermal Insulation is often used as a substitute for soundproofing insulation because of its price consideration however its ability to work as a soundproofing insulation material is three times lesser than that of a soundproofing insulation.
Marine Grade Insulation is specifically designed and manufactured for use in marine vessels and offshore structures. It has much higher fire resistance capabilities than any other type of insulation group and it also has the ability to soak up oil. Marine Insulation also has to comply with ever increasing fire safety standards such as the IMO 2010 FTP code that every few years gets upgraded such as in 1st July 2012.
Soundproofing Grade insulation is designed with the purpose to act as a barrier to prevent noise transference. Unlike thermal insulation material soundproofing does not work well as a thermal barrier. In order to reduce more noise in terms of decibels it needs to be of a very high density such as 150kg density - 250kg densities.
Another difference in the material is the composition characteristics. Soundproofing grade insulation will have a high level of polymer binder, multitude of difference minerals, and not limiting to one type of fibre. This results in the material being extremely difficult and costly to manufacture which leads to very few companies willing to develop machinery to produce.
Acoustic Control or Absorption Grade Insulation will always be quiet low in density, with a reduce amount of binder used and the formation of fibres used are much looser than that of other insulation. Typically Acoustic grade insulation does not necessary need to be formed from just mineral glass fibre alone, Modern methods will use other types of fibres such as manmade and organic.
When using traditional methods of fibres such as Mineral Glass Fibre from mineral or glass based means that a protective membrane must be used to act as a barrier between the material and the environment and then the end user. This is because the nature of the material has low amounts of polymer or resin binders used and will decompose overtime allowing particles to escape into the air; thus resulting in human exposures.
Modern / Current
Modern methods avoid using mineral glass fibres and either use manmade, organic fibres or use polymer foam replacements and in even new developments use synthetic 'rockool' insulation.
Synthetic 'rockwool' insulation is material that works in the same way as mineral glass fibre but with the key difference that it contains no mineral fibres, glass particles, stone or any other such materials.
Misuse of mineral glass fibre material insulation
One of the worst cases of misuse of insulation is the installation of the insulation in Air-Conditioning Systems. The insulation is often placed above ceiling tiles exposed to the open air conditioning return cavity space. The Return cavity works by using fan coil units being distributed in the void area that when working suck into them air from this void and then recirculated back into the environment area below. The main question to mind is if the FCU has a filter installed, and secondary is the filter able to prevent the microscopic particles and fibres from being blown back into the office space. It is a question that many contractors are not willing to answer.
We ask Victor Hipgrave of Microtec who said "rockwool fibres are very similar to asbestos and we know how bad that stuff is... If the fibres and particles are able to circulate and breathed in by people, then it's safe to say it's not going to be good for you".
As well as in the air conditioning open air return system, they can also be found in the ducting itself, sometimes behind perforated metal sheeting, sometimes with a tissue like membrane in front of it. Even with the membrane present should we really be using the material when there is easily available on the market replacements.
One of the other main uses of the material is in the creation of acoustic panels, whereby the insulation is inserted into a timber frame and then fabric is covered over the top to create a panel. They work reasonable well in terms of reducing reverberation noise in the environment they have been installed in. But over a period of time the insulation starts to break down and expel into the nearby area environment.
It is always essential to select the right type of insulation for your purpose of application. The miss use of insulation will result in the poor performance of the material overall.