VIEWPOINT
ROCK OR GLASS:
MINERAL WOOL INSULATION equated to almost half of all insulation sold in the UK in 2022. It’s really no surprise. As well as thermal efficiency, it offers the unique combination of non-combustibility, acoustic performance and sustainability. And it’s easy to install correctly, which means it’s much more likely to deliver its ‘as designed’ performance than rigid insulation boards.
There are two types of mineral wool insulation, glass and rock (also known as stone wool) which look almost identical and have very similar properties. But there are key differences, so it’s important that merchants understand how each material performs so they can recommend the right product for the application. Myth: Use rock mineral wool insulation for acoustic applications Fact: When engineered for acoustic performance, both materials can meet and exceed the noise reduction standards required by Approved Document E. When an absorption layer is required to reduce airborne sound transmission in applications such as internal partitions and floors, we recommend glass mineral wool insulation such as our Acoustic Roll or OmniFit® Slab 35. That’s because glass mineral wool is lighter and easier to handle. We only recommend rock mineral wool insulation where the acoustic design requires additional properties. A good example is warm flat roofs where compressive strength is needed. Myth: Glass and rock mineral wool insulation have different Euroclass Reaction to Fire Classifications Fact: Unlike other mainstream insulants, both glass and rock
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WHICH IS BEST? Matt Neary, National Sales Manager at Knauf Insulation
and is 70% less energy-intensive to manufacture than traditional binders.
mineral wool insulation are non-combustible with the best Euroclass A1 or A2,s1-d0 reaction to fire classification. This means they will not contribute to the development or spread of fire should it occur.
The difference comes when fire resistance is required. Fire resistance measures the ability of a material or a system to resist, and ideally prevent, the passage of fire from one distinct area to another. Rock mineral wool insulation has a higher melting temperature, so is often used in applications where longer periods of fire resistance are required.
Whether the fire resistance of insulation is a critical consideration depends on the application and the rest of the build-up. For example, the insulation used in the separating floor of a loft conversion needs suitable fire resistance because the plasterboard is unlikely to be replaced during the loft upgrade. In this instance, we would recommend a rock mineral wool product such as Rocksilk®
Flexible
Slab, which has been tested to provide 60 minutes fire protection in this application. But in a party wall, the fire resistance comes from the structure, so we’d recommend using a glass mineral wool product such as Knauf Insulation Masonry or Timber
Frame Party Wall Slabs or Supafil® Party Wall. Myth: All glass and rock mineral wool insulation have the same level of embodied carbon Fact: The carbon footprint of a product comes down to what it’s made from and how it’s manufactured. While glass and rock mineral wool insulation are both made from materials that are recycled or come from naturally abundant sources, recycled glass is more readily available and needs less energy to process. Our glass mineral wool products contain up to 80% recycled content such as bottles and jars from household waste that would otherwise go to landfill. Glass mineral wool insulation has other sustainability benefits too. It can be compressed during manufacture, so there’s more product per pack or per pallet. This helps reduce transport- related carbon emissions because more insulation can be transported in one go. These benefits mean that glass mineral wool has the lowest embodied carbon of any mainstream insulant.
Another way we have lowered the carbon of our mineral wool products is through the use of our unique bio-based binder, ECOSE®
Technology. It contains no added formaldehyde or phenol
Of course, merchants can only recommend products with low embodied carbon if they have accurate information. The best way to check is through a manufacturer’s Environmental Product Declarations (EPDs). Another way to check sustainability claims is via the Declare label a ‘food nutrition’ label for construction products. This includes a straightforward ingredients list and shows whether products contain harmful chemicals featured on the ‘Red List’. Knauf Insulation’s entire glass mineral wool product range is Declare ‘Red List Free’. Myth: A pallet of rock mineral wool products holds the same amount of insulation as a pallet of glass mineral wool products Fact: A pallet of our OmniFit® Slab 35 (100mm x 600mm) contains 167% more insulation than a pallet of one of our competitor’s equivalent low density rock mineral wool products. As a result, when we deliver one load of insulation (22 pallets), they need to deliver more than two (47 pallets). It’s all thanks to the compression packaging, I mentioned previously. It means merchants can hold more stock on a pallet, free up space in their delivery vehicles and need to handle much fewer products in the branch.
Thanks to its versatility and unique combination of benefits, mineral wool insulation is an essential part of a merchant’s stock list. So, it’s important merchants understand the differences between how glass and rock mineral wool perform respectively so they can better advise customers about which product to use for the application. BMJ
www.buildersmerchantsjournal.net July 2023
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