Mineral wool insulation encompasses two primary types: rock wool, derived from basalt or diabase, and slag wool, which is produced from the slag of steel mills. Both types are manufactured through a process that involves melting the raw materials and spinning them into fibres, which are then formed into a variety of products, including batts, rolls, and loose-fill insulation. Mineral wool is distinguished by its exceptional fire resistance; it can withstand temperatures above 1,000°C without melting, making it an ideal fire retardant in buildings. This material also boasts excellent sound absorption properties due to its dense fibrous structure, effectively reducing noise transmission between rooms and from external sources.

The thermal resistance, or R-value, of mineral wool insulation varies depending on its density but typically ranges from R-3.0 to R-3.3 per inch. Its ability to maintain performance over time without settling or degrading adds to its appeal in both residential and commercial construction. Additionally, mineral wool is resistant to water and air infiltration, contributing to improved energy efficiency and moisture management within structures. Its natural composition also offers a level of environmental friendliness, as it often contains a high percentage of recycled content. However, careful handling is advised due to the potential for skin irritation and respiratory issues from the small fibres.

Fibreglass insulation, made from fine strands of glass woven together, is one of the most ubiquitous insulation materials in residential and commercial buildings. Its popularity stems from its cost effectiveness and versatility, as it can be installed in various forms such as batts, rolls, and loose-fill to suit different applications—from attics and walls to floors and ductwork. Fibreglass provides good thermal insulation, with an average R-value ranging from R-2.9 to R-3.8 per inch for batts and rolls, making it an effective solution for reducing energy transfer and enhancing indoor comfort. In addition to its thermal properties, fibreglass serves as a sound barrier, dampening noises to create quieter, more serene interior spaces.

One of the advantages of fibreglass is its moisture resistance, which helps prevent mould and mildew growth within insulated areas. However, it should be noted that while fibreglass itself does not absorb water, if it becomes wet, its insulative capabilities can be compromised. Proper installation and a vapour barrier are essential to protect fibreglass insulation from moisture ingress. Despite its benefits, installers must take precautions, such as wearing protective gear, to avoid irritation from the glass fibres. Environmental considerations have also encouraged the development of fibreglass products with higher recycled content, aligning with sustainability goals in construction practices.

Cellulose insulation is favoured for its environmentally friendly attributes, primarily composed of up to 85% recycled paper fibre, with the remainder consisting of fire retardants like boric acid or ammonium sulphate. This green alternative appeals to those seeking sustainable building solutions, offering superior thermal and acoustic insulation. The dense packing of cellulose allows it to fit snugly around obstacles and in tight spaces, minimising air leaks and enhancing its insulative performance with an R-value ranging from R-3.2 to R-3.8 per inch. Its ability to create a tight thermal envelope makes it highly effective at conserving energy and maintaining uniform indoor temperatures.

Beyond its thermal and acoustic benefits, cellulose’s composition includes fire retardants, providing increased fire resistance and contributing to overall building safety. It’s important, however, to ensure that cellulose insulation remains dry, as moisture can compromise its effectiveness and potentially lead to mould growth. Professionals advocate for adequate ventilation and moisture control strategies when installing cellulose insulation to safeguard its longevity and performance. Despite these considerations, its high recycled content and energy-saving potential make cellulose an attractive option for eco-conscious builders and homeowners.

Polystyrene, a synthetic aromatic polymer made from styrene monomers, comes in two variations for insulation purposes: Expanded Polystyrene (EPS) and Extruded Polystyrene (XPS). EPS, the lighter and less expensive option, offers versatility in application but with a lower R-value typically ranging from R-3.6 to R-4.0 per inch. XPS, by contrast, provides a higher R-value of around R-5.0 per inch, attributed to its denser structure and moisture resistance. Both EPS and XPS are noted for their strength, durability, and resistance to moisture and air infiltration, making them suitable for below-grade applications and areas prone to moisture exposure.

Polystyrene insulation’s rigid form factor allows for easy cutting and fitting, facilitating installation in a wide range of building scenarios. However, environmental concerns have been raised regarding its production and disposal, as polystyrene can be slow to degrade in landfills. Recent advancements aim to make polystyrene insulation more eco-friendly, focusing on recycling programs and efforts to minimise the environmental impact associated with its lifecycle. Despite these concerns, polystyrene remains a popular choice for its insulative properties, particularly in climates where moisture resistance is paramount.

Reflective foil insulation, or radiant barriers, primarily functions by reflecting radiant heat rather than absorbing it, making it uniquely effective in hot climates or sun-exposed areas. Consisting of thin layers of aluminium foil laminated to various substrates, reflective foil can achieve significant reductions in heat gain, thereby lowering cooling costs in buildings. Unlike traditional insulative materials that rely on trapping air to reduce heat flow, reflective foil’s efficacy is measured by its reflectivity and emissivity, offering a different approach to insulation.

Although reflective foil does not have a traditional R-value like bulk insulation materials, its performance is evaluated based on its ability to reduce radiant heat transfer. Proper installation is critical, often requiring an air gap between the foil and the adjacent material to function correctly. Reflective foil is lightweight, easy to install, and acts as an effective vapour barrier, enhancing its utility in comprehensive insulation systems. Its role in improving energy efficiency, especially in attic spaces or roofing systems, underscores its value in targeted applications designed to combat heat transfer challenges unique to specific climates and building designs.