How to Choose Glass Wool Wall Insulation?

Apr. 28, 2025

How to choose exterior wall insulation materials

At present, the exterior walls of many houses need thermal insulation. There are many thermal insulation materials on the market. How to choose them? If the thermal conductivity, fire resistance and bulk density of the thermal insulation material meet the requirements, it can be fully used. Because the specific reasons are reflected in the above three aspects.

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Thermal conductivity

The so-called thermal conductivity refers to the heat loss per unit time of the inner and outer sides of the insulating material we choose. Therefore, from this point of view, the lower the thermal conductivity of the insulation board, the better. This is also one of the most critical factors for the insulation performance of insulating board.

For example, the most commonly used external wall insulation board is basically centrifugal glass wool material, and the thermal conductivity is generally between 0.03 and 0.047 w / kg When we choose insulation board, we should refer to the thermal conductivity of polystyrene board above. In other words, the thermal conductivity of the thermal insulation materials we choose is generally less than or equal to the thermal conductivity of these thermal insulation boards, which can meet the effect of our indoor thermal insulation. Therefore, as long as the thermal conductivity of the plastic foam board we choose is qualified, it is suitable for thermal insulation performance

Fire performance

The so-called fire performance refers to the performance of this material when it is on fire. Because we use this material for external wall insulation, we have high requirements for the thermal insulation and fire resistance of the material. Because once the exterior wall catches fire, the problem will be very serious.

The basic requirement of fire resistance of ordinary exterior wall insulation board is flame retardant. When we choose exterior wall insulation materials, we should also refer to their fire resistance. In fact, the fire performance is the fire rating described above. As long as the fire resistance rating we choose meets the requirements, it is also suitable for external wall insulation materials.

Bulk density of insulating board

The bulk density of the insulating board actually refers to the density of the insulating board we choose. Because our insulation board needs to be pasted on the outer wall, if the density of the insulation board is very poor, the firmness of this material is very low, and the consequence in the later stage is that the insulation board falls off from the wall. This possibility is very high. As the external wall is greatly affected by the lateral wind pressure, the requirements for its bulk density are also very high. At present, the unit weight of some thermal insulation materials commonly used for exterior walls basically exceeds 24 kg / m3.

Glass wool or mineral wool - which is best for insulation?

When you’re insulating a building, it is important to ensure you have the best materials for the job. Fibreglass and mineral wool are two of the more popular types of insulation for this kind of project, and both will provide you with individual benefits depending on your requirements.

We’ve packed this handy guide with useful information for you so that you’re fully informed of some of the important factors to consider when deciding if fibreglass or mineral wool is the go-to for you.

Without further ado, let’s dive right in.

Glass wool insulation

Glass wool insulation, also known as fibreglass, is made from glass fibres. Glass is heated to very high temperatures until it melts, and is then spun quickly to create fibres. These fibres are then bound together to be used as insulation.

The glass fibres create pockets of air which act as barriers to prevent heat loss because air is a poor conductor of heat. Glass wool can be found in batts and rolls, loose-fill insulation and also within insulation boards.

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Mineral wool insulation

Mineral wool, also known as ROCKWOOL or stone wool, is made from a selection of raw materials, such as stone and glass. These raw materials are treated in a similar way to glass, in that they are melted at high temperatures until they melt, and then they are spun to form fibres, similar to wool. This wool is then packaged up into batts, rolls or slabs.

R-value

When comparing ROCKWOOL and fibreglass batt wall insulation, they have a roughly similar R-value of around 0.57 per inch of thickness. Because they have the same thermal conductivity – for instance, 0.044 W/mK for both Knauf Loft Roll Earthwool Insulation and ROCKWOOL Twin Roll Insulation – they will provide equal performance in this department.

Sustainability

If you’re looking at the most sustainable option, glass wool is generally made up of up to 86% recycled materials, whereas mineral wool in comparison consists of up to 70% recycled materials. As environmental impact and sustainability are becoming more of a focus, this is becoming more of an important factor when choosing the right insulation material.

Sound insulation

In terms of sound insulation, mineral wool is often the preferred choice for noisy areas. This is because it is much denser than glass wool, so much less sound travels through the insulation.

Ease of installation

If you’re considering installing the insulation yourself, mineral wool is considered much easier to handle. Although heavier than glass wool, mineral wool is much easier to cut, move and fit into place. Glass wool on the other hand is limper, which makes it hard to fit into the spaces required.

Moisture resistance

If you’re looking for a moisture-resistant form of insulation, mineral wool is the clear winner. Mineral wool is resistant to water, so it doesn’t get damp and provides good growing conditions for fungi, mould, mildew or other bacterial growth.

Glass wool, on the other hand, can get damp, as well as promote the growth of fungi, mildew and rot, causing its insulating properties to be severely reduced.

Fire resistance

Although both mineral wool and glass wool are non-combustible, mineral wool has far better fire-resistant qualities, so much so that it can be used as a fire stop. So, this is something to consider if where you’re installing insulation is going to be at risk of fire, and to what extent.

Cost

If you’re conscious of a limited budget, then glass wool may be the choice of insulation for you. It can cost around 10% less than mineral wool and still is effective at insulating your home to reduce heat loss and energy bills.

Final thoughts

Glass wool and mineral wool are both types of insulation materials commonly used in construction.

While both offer excellent thermal insulation properties, mineral wool tends to have superior fire resistance and moisture resistance compared to glass wool, making it suitable for applications where these properties are crucial, such as in high-temperature environments or areas prone to moisture exposure.

Additionally, mineral wool is denser and heavier than glass wool, providing better sound insulation capabilities.

Now that you know how these two insulation options compare, you can easily choose the right one for your specific needs.

Whichever form of insulation you choose, insulating your home is a great way to keep your home warm, prevent heat loss and reduce energy bills. Call our team of experts today for any queries or advice on 692 206.

Contact us to discuss your requirements of Glass Wool Wall Insulation. Our experienced sales team can help you identify the options that best suit your needs.