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Rockwool Insulation Slab

Rid yourself of everyday disturbances and focus on what matters with Rockwool insulation slabs. These 1200mm x 600mm slabs are the best acoustic insulation solution on the market; making Rockwool market leaders and a premium brand name within the insulation industry. These dense, easy to cut slabs are available in varying thicknesses that range from 25mm to 140mm. We recommend these insulation slabs to people seeking a robust 3-in-1 acoustic, thermal and fire insulation solution.

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What Is Rockwool Insulation?

Rockwool is one of the leading manufacturers of rock mineral wool insulation (also known as stone wool insulation) designed to impede sound transmission between rooms. At Materials Market, we sell a vast range of Rockwool insulation solutions, including Rockwool Flexi slabs and Rockwool RWA45 acoustic slabs

These resin-bonded rock mineral wool slabs are purposed to quell unwanted sounds and prevent voice leaks in your home, helping you to live in sweet, manufactured silence. Not only do these premium-quality semi-rigid slabs excel in their soundproofing abilities but they are also rated A1 (non-combustible) on the Euroclass scale, which means they are high performers when it comes to reducing fire spread. 

With a thermal conductivity of 0.035 W/mK, you can rest easy knowing they are working on protecting the thermal envelope of your home. Rockwool is a robust acoustic, thermal and fire insulation suitable for a range of general building projects as well as specialist specifications such as commercial, leisure, industrial buildings and more.

Characteristics of Rockwool Insulation Slabs

● Semi-rigid - Rockwool slabs are semi-rigid meaning you do not have to worry about bowing or sagging over time. 

● Reduces sound transmission - Rockwool slabs are designed to reduce sound transmission. Rock is a naturally poor conductor of sound, making Rockwool the perfect choice for people who want to insulate their homes against unwanted noise. 

● Fire-Protection - Rockwool slabs are manufactured using anti-flammable, thermal insulation material. They are made in part from basalt, a volcanic rock that is highly fire-resistant. The slabs rank Euroclass A1 non-combustible.


Rockwool Flexi Insulation Slabs

Rockwool has been producing insulation slabs since the early 1900s and are focused on ‘rising to the development challenges of modern living.’ One of their most innovative solutions is the Rockwool Flexi insulation slab. Like all other slabs in our Rockwool range, the Flexi slab is extremely fire and sound resistant.

Each slab comes with a unique, flexible edge along one side. The edge is patented, which means that you will not be able to get a tighter friction fit with any other slab insulation. The flexible edge allows the slab to fit to almost any framework. This innovative solution reduces the possibility of air gaps, which further strengthens the product’s insulating properties.

Rockwool RWA45 Acoustic Insulation Slabs

RWA45 is the name that Rockwool gives to their most popular acoustic insulation slab. The RW stands for “Rockwool”, A stands for “Acoustic” and the 45 refers to the fact that these slabs have a density of 45kg/m3 and 0.035 W/mK thermal conductivity, helping you to retain heat in your home. 

RWA45 is one of the top acoustic insulation products that will eliminate unwanted noise from inside and outside homes and commercial spaces. They can fit into internal and separating walls. Once in place, Rockwool acoustic thermal insulation slabs will reduce noise transmission from adjacent rooms whilst providing exceptional fire resistance. Whether you want a peaceful night’s sleep or an uninterrupted boardroom meeting, Rockwool is the perfect solution.


Density of Rockwool Insulation Slabs

The density of Rockwool is measured in kilograms per cubic metre (kg/m3). The denser the slab, the better the sound reduction.

Rockwool slabs are designed for lots of different purposes. Each product type has a different density. We stock RWA45 that are available in a range of thicknesses and have a density of 45 kg/m3. Our RWA45 products are popular middle of the range options that fit lots of insulation needs. Our RWA45 products have a Lambda value of 0.035 W/mK.

Rockwool Insulation Thickness

The thickness of Rockwool slab acoustic insulation vary. Our customers can choose from 25mm, 50mm, 75mm, 100mm, and 140mm thicknesses. The government recommends using 250mm thick rock wool insulation in loft spaces to cut your energy bill by up to 20%. With our wide range of thicknesses, you have the freedom to build structures that suit your space.

Frequently Asked Rockwool Insulation Slab Questions

Rockwool Insulation Storage & Handling

Rockwool insulation slabs have a soft, fibrous texture, very similar to a loaf of bread. Because of this, a serrated blade is all you need to slice through it.
When it comes to storage, we advise that you store the slabs inside; keeping them nice and dry.

Is Rockwool Insulation Fireproof?

Rockwool insulation’s fire performance rating is excellent. The slabs can withstand temperatures up to a whopping 1,000 C. 

Rockwool insulation slabs are classed as A1, the highest possible level on the Euroclass system, which means that they are fire retardant in accordance of BS EN 13162.

Where Can I Apply Rockwool Insulation Slabs?

Due to the rigid, semi-rigid and flexible nature of stone wool insulation, the slabs offer outstanding thermal and acoustic protection in internal walls and floors. They can also be slotted into spaces like partition walls with ease, whether these have a brick, concrete, timber frame or other base structure. This also ensures they are easy to lay in-between floors as sound insulation slabs too. Overall, Rockwool is an all-rounder given it is can be considered for roof, floor and wall insulation. 


Stone wool is water repellent while simultaneously allowing water vapour to pass through. This makes our slabs a great addition to ceilings and basements, where moisture and damp could otherwise pose problems.

The slabs can be used for the following construction types: