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Rockwool Flexi Slab Insulation

Rockwool Flexi Slab Insulation

  • Cavity & Timber Frame Insulation
  • Rockwool

  • Free Next Day Delivery (over £500) in the West Midlands
  • Free Standard Delivery (over £500)
  • View our guides for Help & Advice
 (   Ex. VAT) £60.00
 - £63.60
All prices are including VAT

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🚛 Next Day Delivery (West Midlands) – FREE on orders over £500

Created using patented technology, ROCKWOOL FLEXI® is designed to be a flexible and unique insulation product. With a quick and simple and secure friction fit, the flexible edge allows for a perfect fit between the product at the supporting framework for the best possible results.  

This material can be used for cavity wall insulation, and is fire-resistant with acoustic properties.  

ROCKWOOL FLEXI® can be used for a variety of different applications, including rafter, external walls, partitions and floors.


  • Uniquely designed
  • Made of rock mineral wool 
  • Ideal for cavity wall insulation  
  • Fire-resistant with acoustic properties  
  • Flexible for perfect fit  
  • Easy installation 
  • Thickness: 50mm / 100mm 
  • Length: 1200mm / 1200mm 
  • Width: 400mm / 400mm 
  • Coverage: 5.76m² per pack / 2.88m² per pack 
  • Thermal Conductivity: 0.035 - 0.038W/mK / 0.035 - 0.038W/mK
  • Euroclass Fire Classification: A1 / A1  
  • Unit pack Quantity: 12 / 6  

DISCLAIMER: Please make sure this product meets fire safety regulations for your project.


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Frequently Asked Questions

ROCKWOOL FLEXI offers versatile insulation solutions and can be installed in a variety of applications. This material is commonly used for cavity wall insulation, where it helps reduce heat loss and improve energy efficiency. It is also suitable for applications such as insulating rafters, external walls, partitions, and floors. Its adaptability makes it a valuable choice for various construction and insulation projects, providing effective thermal and acoustic insulation where needed.

Rockwool Flexi Slab Insulation can be installed in various ways, including between wall studs, ceiling joists, and floor joists. To install, measure and cut the insulation to fit the designated area, ensuring a snug fit without gaps. It can be friction-fitted or held in place with mechanical fixings, depending on the application.

At Insulation King, we offer both ROCKWOOL FLEXI Slab 50mm and 100m ROCKWOOL FLEXI. Factors to consider when choosing the right size for your project include local building regulations, insulation goals, climate, available space, energy efficiency, and soundproofing needs. Thicker insulation generally provides higher thermal resistance and is suitable for colder climates, while thinner options may suffice in spaces with limited room. Consulting local regulations and our insulation experts can help you choose the appropriate size for your project.

Yes, ROCKWOOL FLEXI is considered environmentally friendly. It is made of sustainable and recyclable materials and has a low environmental impact. Additionally, it is energy-efficient, helping to reduce energy consumption and greenhouse gas emissions in buildings. Discover everything you need to know about ROCKWOOL insulation here

Free shipping will automatically be applied to all orders over £500. Simply add over £500 to your cart and you will see the discount while checking out.

Orders under £500 - £50 charge.
Over £500 is free.

We typically deliver orders within 2-3 business days of ordering.

Orders for the West Midlands will be completed in 1 to 2 working days.

Orders for areas out of the West Midlands will be completed in 3 to 4 working days.

Orders made after 5pm will be processed on the following working day.

Our deliveries are typically made between 8am and 5pm, Monday - Friday excluding Bank Holidays (Great Britain).

We are unable to offer timed deliveries.

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