Fibreglass insulation is a type of insulation that can resist the thermal bridge effect. It consists of fibres produced by spinning molten glass into fine, durable threads. In an effort to make it easier to install, manufacturers also produce batts which are pre-cut sections of insulation made up of a foam backing and metal facing on one side to create an airtight seal.
Insulation glass fibre is thought to be a safe alternative for homeowners who want increased energy efficiency and safety – as it is fire resistant and does not contain hazardous materials. It has been found in government studies to have about the same cost per square foot as other types of insulating materials, such as polyurethane foams or cellulose fibres.
Fibreglass insulation is made from glass fibres by fibreglass manufacturing companies. It is almost always produced using continuous filaments, which are spun into extremely fine fibres for use in commercial and residential construction. Air-filled or loose-fill fibreglass insulation is also available.
The stranding process of fibreglass rope manufacturing is similar to that of steel cable, and therefore it can be considered a type of steel product manufacturing. In the twisting process, the spiral strand composed of a series of filaments is around 3 turns, and the amount of twists per turn becomes smaller as more turns are added until the amount reaches zero.
The reduction of elasticity means that the toughness of the fibreglass rope can be increased, and it is usually twisted into fibreglass rope with a twist rate of 30-45 turns.
The mechanical properties of fibreglass rope are also improved by increasing the number in the process. Some suppliers do not heat-treat their fibres to make them stronger or provide other desirable properties, so some manufacturers blend fibres during or after spinning to obtain these benefits. For this mixed material, manufacturers use a special process to make them even more uniform and consistent in length and diameter distribution (L&D).
Other advantages include low density, slow moisture absorption, low permeability and resistance to fungus growth.
Disadvantages of fibreglass insulation in comparison to other insulation materials include:
Fibreglass installations are usually not considered a fire hazard. The fibreglass is usually not flammable and combustion of the insulation itself does not cause a fire. Fibreboard and open-cell spray foam panels can “ignite” if exposed to the burning of thermoplastic framing materials, such as wood or masonry. Such ignitions always involve the presence of overhead conductors, however. This could explain the reports of fibreglass insulation fires under electrical panels (generally in older properties).
Insulation glass fibre may contain asbestos, which is a hazardous and highly toxic mineral. Asbestos fibres can be released and inhaled when insulation is handled, or when it is disturbed by natural forces or by construction work. This may cause serious health problems, including lung cancer. It is important to use proper precautions during the installation and removal of this type of insulation, to keep it from being disturbed. Inhaling asbestos has been shown to elevate the risk for certain cancers including lung cancer and mesothelioma.
Fibreglass insulation is considered by some insurance companies to be a safer, cleaner alternative to traditional insulation materials. However, the material is not completely risk-free, as small fibres of asbestos are often present. The installation and removal processes for fibreglass insulation must be carried out carefully for this reason.