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Glasswool Vs Rockwool: What’s The Difference?

The comparative properties of Glasswool Vs Rockwool have long been a contested topic. Perhaps what underpins the confusion surrounding both materials is the catch-all term ‘Mineral Wool‘ – which is often used to refer to both interchangeably.

What unites glass wool and rock wool in their commonalities is their similar production process. Both are made from natural materials which are spun into fibres and formed into sheets using a binding agent.

However, to mark the distinctions between each we must first understand their manufacturing process, insulating properties, and suited applications.

Without further ado, let’s get into it.

What Is Glass Wool Insulation?

Glass wool insulation, otherwise known as Fibreglass Insulation, is an insulant manufactured from a combination of natural and recycled glass.

Glass wool insulation can come in a variety of forms, including rolls or batts, loose-fill insulation, and pre-cut sections. It is a cost-effective, energy-efficient insulation material that can reduce heat loss and improve energy efficiency in a wide range of applications, including walls, floors and attics.

While it boasts the same fire rating as rock wool (A1 non-combustible) and similar thermal properties, the maximum temperature that glass wool can tolerate (without any loss to its insulation properties) is considerably lower than rock wool insulation products. In turn, rock wool products have better fire resistant qualities.

How Is Glass Wool Insulation Made?

Fibreglass Insulation.

Glass wool is made by liquifying glass which is then spun to form fibres.

These fibres are held together by a binder, typically made of a thermosetting resin. This binder helps to create an entangled fibre network and improves the material’s handling characteristics – making the end product easier to install.

What Is Rock Mineral Wool Insulation?

Rock wool also referred to as stone wool, is one of the most commonly utilised insulation materials for soundproofing. Manufactured from raw materials such as rock and stone (both of which are poor sound conductors) rock wool insulation does an excellent job of absorbing sound.

As well as providing excellent sound isolation between floors and internal walls, rock mineral wool delivers unrivalled fire performance. Not only does it achieve the highest possible fire rating (A1), Rockwool is able to tolerate higher temperatures than glass wool without it taking a toll on its thermal insulation performance.

Another ‘one up’ that rock wool has on glass wool is the fact that its fibres are slightly shorter than glass wool’s. These shorter fibres lend themselves to rock wool’s greater compressive strength.

How Is Rock Mineral Wool Made?

Rock Wool Insulation.

The manufacturing process of rock mineral wool is similar in many ways to the process used to make fibreglass insulation. The main difference, of course, is the fact that rock wool utilises rock instead of glass.

To manufacture rock wool, volcanic rock is heated until it reaches a sweltering 1,500°C and liquefies. After that, the molten rock is furiously spun in a rotary process to produce rock mineral wool fibres. These fibres are then bound with resin. This exact same resin is used in the manufacture of glass wool. However, unlike glasswool, trace amounts of oil are added to mineral wool to minimise dust.

Glasswool Vs Rockwool Applications

Rock Mineral Wool insulation can be used in a variety of applications due to its density and fire-resistant properties. It is often used in:

– Walls

– Floors

– Ceilings

Glass Mineral Wool insulation is most commonly used in residential and commercial buildings. It can be used in:

– Walls

– Ceilings

– Floors

– Lofts

– Ceilings

Glasswool Vs Rockwool – Key Differences

●     Eco-friendly – Rock mineral wool is made of up to 80% recycled content, whereas fibreglass is only made from up to 30%. Unlike rock wool, fibreglass is sourced from non-renewable materials, specifically plastic reinforced with glass fibres.

●     Weight/Acoustic Performance – Rock wool insulation slabs are far heavier and denser than fibreglass slabs, making them a better sound insulation choice.

●     Durability – Rock wool products do not bend or sag as easily as fibreglass insulation slabs.

●     Installation – Firm mineral wool slabs can friction-fit into place between studs and joists. Installing fibreglass can be more complicated because it requires staples and/or wires.

●    Fire resistance – Both fibreglass and mineral wool insulation possess exceptional fire-resistant qualities and are classed as A1 non-combustible on the Euroclass scale. This classifies that they do not burn and offer premium fire protection.

●    Thermal performance – When comparing rockwool and fiberglass batt wall insulation, both materials have a general thermal conductivity of around 0.044W/mK.

Glasswool Vs Rockwool – Conclusion

When choosing between both glass wool and rock wool, it is important to consider the specific requirements of the project at hand. Requirements to consider are: thermal performance, sound insulation, cost, and environmental impact.

In applications where sound insulation takes precedence, using rock mineral wool is your best bet. When looking for a lighter-weight thermal solution to insulate your walls/loft space on a budget, then glass mineral wool is likely the way to go.

If you’re unsure what’s best to use, then contact us and we can help advise. We sell both Rock Mineral Wool insulation and Glass Mineral Wool insulation at Materials Market.

Always consult a professional.

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