ROCKWOOL® launches the UK’s most thermally efficient stone wool for cavity walls

  • 28 Sep 2022

ROCKWOOL has launched NyRock® Cavity Slab 032, providing specifiers with a low lambda, non-combustible stone wool slab for full and partial fill masonry cavities that enables a thinner wall construction.

NyRock Cavity Slab 032 has been developed using NyRock technology, the manufacturer’s patented production process that creates a more efficient fibre structure than traditional stone wool products. 

With its 0.032 W/mK thermal conductivity value, users can achieve a U-value of 0.18 W/m²K with a thickness of 150mm, depending on construction type, which is 25mm thinner than standard stone wool cavity products within the same wall build up.

As with all ROCKWOOL stone wool insulation, NyRock Cavity Slab 032 can withstand temperatures in excess of 1000°C, achieving the highest Euroclass A1 non-combustible reaction to fire classification.


It also benefits from a high density semi rigid composition meaning it will not slump in the cavity and retains the same thermal and fire resistance properties more than 55 years after installation according to independent research.[1]

NyRock Cavity Slab 032 comes in 455mm widths to suit standard vertical wall tie spaces and achieves a closely knitted joint with adjacent slabs, without the need for taping of the joints. This helps eliminate gaps allowing for continuity of insulation across the cavity.

‘Real and immediate challenge’

Paul Barrett, Head of Product Management at ROCKWOOL UK, comments: “Energy efficiency is a very real and immediate challenge for the construction sector.

“Alongside the need to improve the thermal effectiveness of existing buildings against a backdrop of rising energy bills, our eyes must also be on the more onerous requirements of the Future Homes Standard and the UK’s wider 2050 net zero carbon target too.

“NyRock Cavity Slab 032 gives specifiers a new level of thermal performance for stone wool alongside spacing saving capabilities, and acoustic and fire performance that are equally critical when providing occupants with comfortable and safe spaces.

“These performance benefits are also backed by a strong commercial offer including a competitive price point and installation efficiencies such as ease of cutting and fitting on-site.”

Having undergone an extensive testing programme, NyRock Cavity Slab 032 is suitable for new build, renovations and extensions and has British Board of Agrément (BBA) certification[2] for full and partial fill applications.

All ROCKWOOL stone wool insulation comprising NyRock technology have water repellent properties and can be recycled indefinitely. Stone wool insulation is manufactured from naturally occurring volcanic rock that is abundant in supply as it is continually replenished by the earth’s crust.

For more details on NyRock Cavity Slab 032 and the wider NyRock range, visit


United Kingdom,
CF35 6NY

Phone: 01635 862621
Fax: 01656 862302

Visit the ROCKWOOL website

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