Knauf Rocksilk® RS45 Building Slab | 1200mm x 600mm | All Sizes

KnaufSKU: IUK00869

Sale price£48.28 

inc VAT

Pay in 3 prices shown are an example only. Total calculated at checkout.

Delivery within 3 - 5 working days

Free Delivery On Orders
Over £599.95 Ex-Vat

Need something quicker?

Contact us on 0300 303 4578
or email here!

Knauf Insulation Rocksilk® RS45 Rock Mineral Wool Slabs: The Ultimate Solution for Thermal, Fire Protection, and Acoustic Applications


Discover the versatility and superior performance of Knauf Insulation Rocksilk® RS45, an exceptional rock mineral wool slab designed to excel in a wide range of applications.

Certified non-combustible with a Euroclass A1 fire classification, this product ensures maximum safety. Manufactured using Knauf Insulation's innovative bio-based ECOSE® Technology, Rocksilk® RS45 not only meets but exceeds the most stringent environmental and health standards.

Key Benefits

  • Multipurpose Efficiency: Ideal for diverse applications, from ground and internal floors to roofs and partitions, ensuring comprehensive coverage and convenience.
  • Superior Sound Absorption: Crafted from high-density rock mineral wool, Rocksilk® RS45 offers unmatched sound reduction capabilities, making it a top choice for acoustic management.
  • Enhanced Fire Resistance: Boasts a melting temperature exceeding 1000°C, providing extended fire resistance superior to many other insulation materials.

Knauf Insulation Rocksilk® RS45 Rock Mineral Wool Slabs available sizes:

Thickness Thermal Resistance Length Width Slabs Per Pack
25mm 0.70m2K/W 1200mm 600mm 20
30mm 0.85m2K/W 1200mm 600mm 16
40mm 1.10m2K/W 1200mm 600mm 12
50mm 1.40m2K/W 1200mm 600mm 10
60mm 1.70m2K/W 1200mm 600mm 6
75mm 2.10m2K/W 1200mm 600mm 6
100mm 2.85m2K/W 1200mm 600mm 5

Product Specifications

Specification Value
Thermal Conductivity  0.035W/mK
Fire Classification A1
Generic BRE Green Guide Rating A+
Vapour Resistivity 5.00 MNs/g.m
Material Rock Mineral Wool
Density 45kg/m3


Rocksilk® RS45 is perfect for:

  • Floor Insulation: Including ground floors and separating floors where thermal and acoustic insulation is crucial.
  • Roof Insulation: Ideal for pitched roofs at rafter level, enhancing both thermal efficiency and fire safety.
  • Wall Insulation: Excellent for internal walls, partitions, and frameworks in both light steel and timber constructions, providing robust fire protection and soundproofing.

Frequently Asked Questions (FAQs)

What is Knauf Insulation Rocksilk® RS45?

Knauf Insulation Rocksilk® RS45 is a rock mineral wool slab designed for versatile applications in thermal insulation, fire protection, and acoustic improvements. It is recognized for its non-combustible properties with a Euroclass A1 fire classification and is made using an eco-friendly, bio-based binder known as ECOSE® Technology.

What is the difference between Knauf Insulation Rocksilk® RS45, RS60, RS80, RS100 and RS140?

The Knauf Insulation Rocksilk® RS range consists of mineral wool slabs that differ primarily in density, which affects their thermal and acoustic insulation properties. The RS45, RS60, RS80, RS100, and RS140 are all designed for various applications but vary by density and, consequently, by their specific use-cases:

  • RS45 has a density of 45 kg/m3, making it suitable for a broad range of general applications where moderate insulation is needed.
  • RS60 has a density of 60 kg/m3, offering enhanced thermal and acoustic performance suitable for more demanding environments.
  • RS80 and RS100 increase in density and are typically used where higher performance insulation is necessary, such as in industrial applications or where superior fire resistance is required.
  • RS140 has the highest density at 140 kg/m3, providing the maximum level of insulation and fire protection, making it ideal for specialized applications needing the highest performance material.

Each slab type is also available in various thicknesses to accommodate different requirements, ensuring versatility across a range of construction scenarios.

How does Rocksilk® RS45 contribute to fire safety?

Thanks to its high melting temperature of over 1000°C, Rocksilk® RS45 provides enhanced fire resistance compared to other mainstream insulants. Its composition and structure make it an ideal choice for areas where high levels of fire safety are required, as it effectively helps in containing fires and preventing the spread of flames.

Can Rocksilk® RS45 be used for both thermal and acoustic insulation?

Yes, Rocksilk® RS45 is extremely effective for both thermal and acoustic insulation. It offers excellent levels of sound absorption and reduction, making it suitable for environments where noise reduction is critical, such as in multi-residential buildings or offices. Additionally, its thermal insulation properties help maintain consistent indoor temperatures and reduce energy costs.

What are the environmental benefits of using Rocksilk® RS45?

Rocksilk® RS45 is manufactured using Knauf's ECOSE® Technology, a bio-based binder that is free from formaldehyde, phenols, acrylics, and artificial colours. This makes it more environmentally friendly compared to insulations that use traditional chemical-based binders. Furthermore, the rock mineral wool is sustainable and contributes to a healthier indoor air quality.

Is Rocksilk® RS45 suitable for all building types?

Rocksilk® RS45 is versatile enough to be used in various building types, including residential, commercial, and industrial properties. It can be applied in multiple areas such as internal floors, separating floors, pitched roofs at rafter level, and various wall systems including light steel frame and timber frame walls.


Data Sheet PDF download - Click Here


    Order Value Delivery Charge
    Up to £200.00 ex-vat £100.00 ex-vat
    £200.00 - £599.95 ex-vat £59.95 ex-vat
    Above £599.95 ex-vat Free Delivery


    Weekend Delivery
    Available upon request


    Parcel Rates
    Delivery charge may vary depending on quantity and volume of your order.
    Pricing will be calculated during checkout.


    Local Delivery Charge
    Within 35 miles of Postcode S63 9BL - Up to £500.00 ex-vat
    Delivery Charge £35.00 ex-vat
    Please contact us to arrange collections
    Tel: 0300 303 4578 | Email:


    Delivery charges will automatically be calculated within the checkout process.
    Orders are only processed for delivery between 8.00am - 5.00pm Monday to Friday excluding bank holidays.
    Moffett offload will be used for large bulky deliveries and only when agreed with you.
    Please advise of any access issues on ordering.
    Delivery is Kerbside only.
    In the unlikely event that your delivery is not correct or damaged please notify us immediately and mark any issues on the delivery slip.


      Where We Deliver

      Delivery Areas

      We have a fleet of FORS delivery vehicles all with Moffett mechanical off loads that deliver nationwide. Sometimes we may use 3rd party carriers for smaller orders.


        Product Delivery Times

        The vast majority of our orders are dispatched within 3 working days, this can however be up to 5 working days, please contact us if you require something urgent.
        Speciality items may take up to 5-7 working days.
        We will contact you with in 24/48hrs of your order been placed to confirm delivery times and dates.

          Enter the width(m) and length(m) of your project below:

          You may also like...

          Customer Reviews

          Based on 2 reviews
          Paul Townsend
          Knauf Earthwool / Rocksilk Building Slab RS45 | 1200mm x 600mm

          Expert advice an delivered quickly.

          Knauf Earthwool / Rocksilk Building Slab RS45 - 1200mm x 600mm

          Easy to work with (make sure you cover up or it gets a bit itchy). Time will tell how effective it is, but it looks to be better than insulation I’ve used previously.