Mineral Wool Insulation

What is Mineral Wool Insulation?

Mineral wool is a category of insulation produced by heating natural and recycled mineral materials to extreme temperatures and spinning the molten mass into fine, fibrous strands. These fibres are then compressed and formed into finished products including slabs, rolls, boards, batts and pipe sections. The raw materials vary by product type: stone wool is derived from volcanic basalt rock, while glass wool is produced from silica or recycled glass cullet. Both processes result in a robust, non-combustible insulation material that performs consistently across thermal, acoustic and fire-resistance requirements. Mineral wool has been a staple of UK construction for decades and remains one of the most widely specified insulation materials on the market. Its versatility across applications and sizes such as 100mm and 200mm, combined with a strong fire classification and genuine acoustic credentials, makes it a practical choice for residential, commercial and industrial builds alike.

Stone Wool and Glass Wool

The two principal types of mineral wool differ in their raw material composition and, as a result, in certain performance characteristics. Stone wool, sometimes referred to as rock wool, is manufactured from volcanic basalt and is capable of withstanding fire temperatures in excess of 1,000°C without structural failure, carrying a Euroclass A1 or A2-s1,d0 non-combustible fire classification under EN 13501-1. It is the preferred choice wherever fire compartmentation, party wall compliance or protection of structural elements is required. Rockwool is the leading stone wool manufacturer, offering a broad range of slabs and rolls suited to walls, floors and roofs.

Glass wool is produced from silica or recycled glass and typically achieves slightly lower lambda values, making it a highly effective thermal performer in loft and partition applications. Knauf, Superglass and Isover manufacture the leading glass mineral wool products in the UK, including loft rolls, acoustic partition rolls and between-rafter batts.

Applications

Mineral wool insulation is suited to a broad range of applications across the building envelope. In wall construction, stone wool slabs are used in full-fill and partial-fill cavity walls, external wall insulation systems, and internal stud or metal frame partitions. Glass wool rolls and batts are commonly installed between ceiling joists, across loft floors and within rafter bays for pitched roof insulation. Pipe sections of mineral wool provide thermal protection and fire resistance for mechanical services in commercial and industrial settings.

Acoustic performance is one of the defining characteristics of mineral wool, and it is the material of choice for separating floors, party walls and stud partitions where compliance with Approved Document E is required. High-density stone wool slabs are particularly effective in these applications, absorbing airborne sound while also contributing to thermal performance.

Performance

Mineral wool products carry lambda (thermal conductivity) values typically in the range of 0.033 to 0.044 W/mK depending on product density and type, covering the majority of standard wall, floor, loft and roof U-value targets. Both stone and glass wool are manufactured from inorganic materials and do not promote mould, rot, fungi or corrosion in service.

Safe to Specify, Simple to Install

Mineral wool is manufactured from natural and recycled minerals and carries no hazardous classification under current UK regulations. Products are non-combustible, do not off-gas in service, and many modern formulations are free from added formaldehyde, making them straightforward to specify for occupied residential and commercial buildings with confidence. As with any fibrous insulation, gloves and a dust mask are recommended during cutting and installation to avoid temporary skin and respiratory irritation, but these are standard site precautions rather than indicators of any lasting health risk.

Correct detailing is straightforward: mineral wool should be installed alongside appropriate vapour control layers and breather membranes as required by the build-up. Rockwool stone wool products carry a factory-applied water-repellent treatment, so any incidental wetting during the construction phase does not compromise the product, which returns to full thermal performance once dry. Less waste, less rework, less downtime on site.

Why Choose Insulation UK?

Rockwool, Knauf, Superglass and Isover in stock. A comprehensive range of stone wool and glass wool insulation products available for fast UK-wide dispatch.

Free delivery on orders over £500 ex VAT. Competitive trade pricing across the full mineral wool range, with no minimum order on smaller quantities.

Over 50 years of industry experience. A specialist team with detailed product knowledge across the full range of insulation materials and applications.

Trusted by 20,000+ customers. From individual tradespeople to national contractors, we supply to projects of every scale across the UK.

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