Mineral Wool Insulation: An Effective Product?

Mineral wool is an effective structural insulation material. In fact, by 2030, its global market, which is valued at no less than 15.6 billion dollars, could grow by as much as 6%. 

The question is: Why is there such hype around mineral wool insulation, rockwool especially? Mineral wool insulation works well in any room in a house (from the basement to the attic, as well as inside the walls), it’s fairly inexpensive and effective for both thermal insulation and soundproofing, not to mention fire-resistant.

Below is a fact sheet on mineral wool insulation, which details why rockwool is so effective, and why it's so popular amongst construction professionals. 

Rockwool: A Variant of Mineral Wool 

Rockwool is one of the many types of mineral wool used as insulation material, together with glass mineral wool insulation. Obtained from basalt, the most common volcanic rock on the planet, rockwool was originally developed for structural thermal insulation and soundproofing by the construction industry. 

The basis of its success is a rare combination between thermal insulation, sound- and fireproofing.

Rockwool Advantages

High-quality thermal insulation and soundproofing

Rockwool has a thermal conductivity coefficient that’s between 0.033 and 0.040 W/mK. That aside, for a material to be considered an effective insulator, it must have a thermal conductivity coefficient that’s less than 0.065 W/mK, rockwool ranks as one of the best thermal insulators.

In terms of soundproofing, while rockwool insulation doesn't quite match the properties of hemp, it's still the best traditional material in terms of noise absorption, as per research done on its effectiveness.

Therefore, rockwool insulation accounts for two essential characteristics sought after for adequate building insulation: thermal insulation and soundproofing. 

A fire retardant

Rockwool is a fire-resistant material, contributing to the overall level of safety in buildings by limiting the risk of fires spreading. As a matter of fact, rockwool has the distinctive feature of withstanding temperatures of over 1000°C.

Keep in mind that during a house fire, a blaze can reach temperatures of over 1500°C, however, this type of insulation will definitely limit the dangers caused by fire.

Rockwool is lightweight

Rockwool is a particularly lightweight material that has a density of about 40 kg/m³, thus it can be installed by way of panels or a spray. 

When sprayed, it's better known as blown-in insulation. This type of insulation is particularly used in attics and has the added benefit of ensuring the watertight nature of the panels at every joint.

Rockwool isn't carcinogenic

Studies done regarding the potential adverse health effects of rockwool haven't revealed any evidence of cancer, primarily diseases related to the respiratory system. However, breathing in rockwool can cause a cough, runny nose, sore throat, and respiratory tract irritation. 

Rockwool fibres don’t linger in the lungs

Following a sanitary scandal linked to the use of asbestos in building structures, the fear of finding out that rockwool insulation materials had the same health hazards as asbestos insulation became apparent. 

Medical research on animals revealed a significant decrease in rock fibres by more than half within 4 weeks of exposure, while other studies have stressed the lungs' ability to eliminate the fibres before inflammation sets in. In other words, our lungs eliminate the presence of the fibres before damage can be done!

Safety Tips When Handling Rockwool

Installing mineral wool does have its downsides, especially in terms of health hazards. In fact, dermatological studies have noted cases of contact dermatitis induced by the alkaline nature and the spiky shape of the rock fibres.

Hence, when handling rockwool, it's strongly recommended that you wear the following personal protective equipment: 

• Pair of gloves;

• Protective goggles;

• Mask.

Before leaving any work site, we strongly recommend that you vacuum the area clean and air out the space to remove all fibres. 

Rockwool Pricing 

Rockwool is a material that’s relatively easy to find. It’s made in bulk and sold in most retailers. Therefore, choosing mineral wool to insulate the walls of your home, basement, or attic is a pretty convenient option. 

The sole factor that may deter you is its pricing, as mineral wool insulation is a little bit more expensive than other materials like glass wool. Just like with any insulation material, its price tag very much revolves around two elements: the surface area to be covered and the thickness of the product. 

To have a pretty good idea in terms of costs, we’re going to focus our attention on the material’s main manufacturer, the leading Danish company ROCKWOOL. 

Home Depot offers rockwool insulation bundles for:

• Walls with wood studs: $104.93 for 29.4 sq. ft.

• Walls with steel studs: $90.34 for 64 sq. ft.

At BMR stores, you can find something to insulate 37.5 sq. ft. for $80. 

If you’re thinking of insulating your attic with blown-in mineral wool, contact a company that specializes in this type of service. A contractor can provide you with a cost estimate based on the square footage you wish to insulate. 

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Description of Cellulose Fibre 

Source: Unsplash 

Cellulose Wadding: A Less Popular Alternative

Cellulose fibre isn't mineral wool. It's an insulation material made from recycled wood and paper. As a result, cellulose fibre is considered an ecological material. 

This eco-material, otherwise known as cellulose wadding, has an insulation factor similar to mineral wool. In fact, its thermal insulation coefficient is between 0.035 and 0.041 W/mK.

Given this, the question remains: Why is this eco-friendly material, which doesn't result in the same environmental pollution created by rockwool insulation extraction and manufacturing, not favoured in the construction industry? 

For two reasons: Its quality isn’t standardized and it doesn’t withstand humidity very well. 

Varying quality

Cellulose fibre is made from recycled materials, notably newsprint. Its composition doesn't necessarily adhere to precise guidelines, which leads to varying degrees of quality between different cellulose fibre manufacturers. 

This discrepancy is quite significant: It actually results in a 10% thermal conductivity coefficient variation. In other words, the coefficient can reach 0.045 W/mK. However, it's still reasonable in terms of an insulation material option.

Compaction problem

While rockwool is also prone to compaction issues, cellulose fibre will compress by at least 20% of its initial size. Here's why: because it's especially susceptible to humidity. 

These characteristics also contribute to its 10% thermal conductivity coefficient reevaluation. Switching to cellulose fibre means weighing the environmental benefits against the loss of thermal insulation value.

Soundproofing and cellulose fibre

Cellulose fibre offers the best soundproofing. It’s roughly 12 inches thick, and it’ll absorb all noise in your home.

Is cellulose fibre fireproof?

No. Cellulose fibre is made of up as much as 95% recycled wood or paper, so it's far from being fireproof. To ensure a certain fire resistance, at least 5% of its composition is made of boric acid or ammonium salt.

Therefore, these add-ons pose two problems:

• An environmental problem;

• Public health problem. 

In fact, boric acid is a major environmental issue. Industries producing cellulose fibre emit large quantities of boric acid, which results in high levels of localized pollution and a significant impact on biodiversity.

Public health concerns have also been brought up regarding the use of ammonium salt in cellulose fibre insulation materials. Depending on the temperature and humidity levels to which the cellulose fibre is exposed, ammonia can be released into the air, resulting in respiratory tract irritation.

However, as a way of dealing with these issues, some manufacturers mix in up to 15% of fireproof mineral wool, which further reduces the green nature of the material. In other words, using cellulose fibre will come, without a doubt, with some compromises, which may or not be worth it depending on your standards.

Want to learn more about other types of insulation materials similar to mineral wool? Check out our article Mineral Insulation Materials: What You Need to Know!

Source: Unsplash