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25mm Foil Faced Two Sides RS100 Knauf Insulation Slab ǀ pack of 12

25mm FOIL FACED BOTH SIDES RS100 Knauf Rock Mineral Wool Building Slab - 100kg density
25mm Foil Faced Two Sides RS100 Knauf Insulation Slab ǀ pack of 12
  • Class ‘0’ to the Building Regulations Euroclass A1
  • Density: 100kg/m3 Excellent thermal and acoustic properties
  • Class 1 Surface Spread of Flame Non-combustible
  • Provides excellent fire, thermal and acoustic performance.
Estimated delivery:
In Stock
£ 589.85
Ex VAT: £ 491.54
  • Brand: Knauf®
  • Model: 25mm Two Foil Faced RS100
  • Dimensions: 1,200mm x 600mm x 25mm
  • SKU: 25mm FFx2
  • Product code: P1-1170
  • MPN: 25mm Double Sided Foil RS100

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25mm Foil Faced on Both Sides Rocksilk RS100 Knauf Insulation Slab is a high-density (100kg/m3) non-combustible rock mineral wool foil-faced two-sides rigid insulation slab with a great fire performance (Class A1) suitable for use in multiple applications.

Knauf RS100 1200mm x 600mm aluminium foil backed both sides insulation slab provides outstanding fire, thermal and acoustic performance for both new build and refurbishment projects.

These odorless, non-hygroscopic, and rot proof slabs are free of CFCs and HCFCs and will not encourage the growth of fungi, mould or bacteria.

Knauf RS100 Building Insulation Slab comprises a high density rock mineral wool core which is foil faced both sides.

Rocksilk RS foil range is a high-efficiency insulation with a certified lambda value (thermal conductivity) of 0.034W/mK.

RS100 is manufactured with a density of 100kg/m3, designed for use in a variety of applications including internal partitions, timber and metal studs, and in between timber rafters and floor joists.

Knauf Building Slab have excellent sound absorption thanks to excessive density characteristics providing high levels of sound reduction.

Rocksilk RS100 foil insulation slabs are easy to cut and shape with a large bladed knife or saw.

Insulation products made with ECOSE Technology contain no formaldehyde binder, dye or artificial colours.

RS100 slabs are also Zero ODP and Zero GWP which makes them more eco-friendly insulation material.




Width: 600mm

Length: 1200mm

Pack Quantity: 12

Slab Coverage: 0.72m2

Pack Coverage: 8.64m2


Density: 100kg/m3 

R-Value: 0.70m2K/W

Thermal Conductivity: 0.034W/mK

Vapour Resistivity: 5.00MNs/g.m.

Surface Spread of Flame: Class 1 

Building Regulations: Class ‘O’ 

Fire performance: Euroclass A1 (non-combustible)


Key points:

 · High-density of 100kg/m3.

 · Aluminium foil faced on both sides.

 · Formaldehyde binder free.

 · Outstanding thermal performance.

 · Fire classification - non-combustible material. 

 · Single slab can be used for variety of applications.

 · Excellent sound absorption characteristics. 

 · Provides high levels of sound reduction. 

 · Multi-purpose product range.

 · Manufactured using Knauf ECOSE® Technology.

 · A+ BRE Green Guide rating.

 · Thermal conductivity (lambda) of 0.034W/mK.

 · Fire Performance - Euroclass A1 to BS EN ISO 13501-1.

 · Free from CFCs, HCFCs.

 · Odorless, non-hygroscopic, and rot proof.

 · Do not sustain vermin.

 · Easy to cut with a large bladed knife or saw.

 · Free of dye or artificial colours.

 · Zero ODP.

 · Zero GWP.



 · Ground floors.

 · Internal floors.

 · Separating floors.

 · Fabrication.

 · Multi-applications.

 · Pitched roofs at rafter level.

 · Internal walls.

 · Acoustic partitions.

 · Light steel frame walls.

 · Timber frame walls.



 · Eurofins Gold.

 · A1 Euroclass Fire Rating.

 · CE Marking.

 · TÜV Nord.

 · Robust Details.

 · Green Guide Rating A+ - B.


*Further information may be found in our Downloads section.

Fairly easy access to all PDF files.

Datasheet ǀ Declaration of Performance - DoP ǀ BBA Certificate ǀ Installation Guide ǀ Certificates ǀ Brochure ǀ SPEC Sheet 


*Special Product - Non returnable cancelable.

Board covarage 8.64 m2
Colour Brown ǀ Silver
Density 100kg/m3 
Length 1200mm
Material Rock mineral wool ǀ Aluminium Foil
Pack Coverage 8.64m2
Pack Quantity 12
R-Value 0.70m2K/W
Thermal Conductivity 0.034W/mK
Thickness 25mm
Width 600mm
Fire Classification Euroclass A1
Vapour Resistivity 5.00MNs/g.m.
Slab Coverage 0.72m2
Fire Reaction Non-combustible
Building Regulations Class ‘0’ 
Coverage 8.64m2
Finish Composite foil facings
Quantity 12
Shipping method Articulated Vehicle ǀ Courier
Applications Multiple applications
Foil faced Both sides
ECOSE Technology Yes
ETA Notification Yes
Features Foil-faced two-sideds Fire Slab
Manufacturer Knauf Rocksilk®

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We deliver insulation materials to Mainland UK only. Deliveries to Highlands, Northern Ireland, Isle of Wight etc.. might be possible at additional cost.
We offer free delivery on most of the orders above £300 (excluding VAT) (except special products - shipping cost via courier - products marked ''Request A Quote'')

Delivery of some insulation materials might be extended due to the current situation (Covid-19, stock shortages, allocations).
If you need materials quickly please contact us - we will do our best to help you source materials needed.

We do not deliver on weekends and bank holidays. Sometimes we can deliver on Saturdays - please check with us before placing the order.
If you need any further information please contact us tel. 02081910776

We can help to calculate price per m2 or linear meter (one meter in length) cost, please just contact us via phone 02081910776, email or live chat. Alternatively, you can work it out yourself quickly and easily: to get cost per meter square please divide price shown in orange area by ''Required area (m2)'' Example price of £28.80 divided by board coverage 2.88m2 = cost of £10.00 per m2.


No matter whether you choose a local installer or a national company, there’s a few tips to help you find the right installer for your home insulation improvements, such as asking for recommendations and making sure that they’re part of a certification scheme. This makes sure that they have the right skills and standards of workmanship to carry out the installation, and you can be sure that they know exactly what they are doing.


1. Thermal inspection picture in portfolio

It’s worth seeing a installer’s previous work. There’s no harm asking if you can see any properties nearby that they’ve installed insulation in. Best way would be to see Infrared Thermal Imaging Inspections. Thermal cameras spot small, but key changes in temperature in different areas of a house, identifying problematic areas that the human eye never could and some that a visual inspection could only hypothesize.

2. Reviews

Along with checking recommendations and previous work, finding reviews online can often be a great way to find out if they provide a good service or not. However, it’s best not to solely rely on reviews you may find or review websites, as there’s no controlling who writes them.

3. Compare prices

Comparing prices will also ensure companies can’t take advantage of you and give you a fair price. 

4. Word of Mouth

The best way to find a great insulation installer is through recommendations. Make sure you ask friends and family. They will most likely give you their honest opinion and can tell you from first hand experience.


Whether you require a wall, cladding, external wall, loft or floor insulation fitted, you can find and hire your local insulation installers from popular UK web pages. A simple internet search will return thousands of potential installers near your area.



We are the stockist of construction materials and related products for both trade and DIY from most recognizable brands in the UK like Cordek, RCM, Promat, Rockwool, Isover, Celotex, Xtratherm, Ursa, Low-E, Cedral, Kingspan, Dufaylite, British Gypsum, K-rend, Ecotherm, Iko enertherm, Kay-Metzeler, Terrawool to allow you to complete your insulation job on time at competitive prices and the highest standards.


Whether you are a large company or a DIYer, if you need a large amount of insulation materials, we can offer quantity discounts at the best prices. Please contact us and our friendly customer service will try to find the best and cheapest solutions for you. We value your time and we will try to deliver the products as soon as possible at a reasonable price to your construction site or house. The UK's leading insulation supplier near you and your needs. Price List available upon request.
25mm FOIL FACED BOTH SIDES RS100 Knauf Rock Mineral Wool Building Slab - 100kg density
25mm Foil Faced Two Sides RS100 Knauf Insulation Slab ǀ pack of 12
£ 589.85