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Thermoblock insulation
Marmox Thermoblock insulation
Marmox Thermoblock (65mm)

Marmox Thermoblock (65mm)

  • Cavity Wall Insulation
  • Marmox

  • Free Next Day Delivery (over £500) in the West Midlands
  • Free Standard Delivery (over £500)
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🚛 Next Day Delivery (West Midlands) – FREE on orders over £500

Marmox Thermoblock insulation is made to be the perfect solution to thermal bridging. BRE accredited Thermoblock is a block of insulating material designed to be placed at the base of a timber-frame or masonry wall to ensure maximum thermal performance. Marmox Thermoblock insulation is ideal for use throughout a building and is water-resistant, meaning it can be used in damp or humid conditions without become susceptible to mould or losing any insulating properties, automatically creating a moisture barrier.  

With a low thermal conductivity of 0.05W/mK, this Thermoblock insulation features a core made of specially formulated fire-resistant extruded polystyrene for optimal strength. The compressive strength of 9N/mm2 can support up to two storeys of a building. Thermoblock is made even stronger with lightweight columns spaced 60mm apart, reinforced by an advanced epoxy composite. 

Marmox Thermoblock insulation is also coated on both sides with a special layer of alkali-resistant fibreglass mesh embedded in polymer concrete to provide a unique blend of durability and structural support.  


  • Base of timber-frame wall  
  • Base of masonry wall  
  • Base of any other wall with brick, block, or wooden frame  
  • Beneath door and window frames 
  • Roof and wall junctions  
  • At the inner leaf base in the perimeter wall  
  • On party walls  
  • Outer leaves, parapets 
  • Solid single-leaf walls 

Storage: Keep dry, flat, and avoid direct sunlight.  

Installation: See technical manual below.  


  • Highly versatile   
  • Ideal for use at junction where floor and wall meet 
  • Compatible with all block types, bricks and timber frames  
  • Excellent thermal performance   
  • Lightweight 
  • Watertight and moisture resistant 
  • Thermal Conductivity: 0.05W/mK   
  • Compressive Strength: 9N/mm2 
  • R -value = 2 m2 k/W at just 6 cm thickness 
  • Shear Strength: 0.18N/mm2 
  • BBA certified 
  • Eco-friendly with zero GDP and very low GWP  
  • Fire Resistance: Class E 

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

About the Manufacturer  

Marmox offer top-quality insulation and waterproofing products for construction and refurbishment projects. The directors boast over 40 years of expertise in designing, manufacturing, specifying, and marketing construction materials. Whether it's waterproofing, dry lining, sound absorption, or insulation products, Marmox have a wealth of experience. From bath panels to fire protection, wet rooms to mosaics, Marmox consistently provide high-quality services to customers across the UK. 


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Frequently Asked Questions

Marmox Thermoblock is made of extruded polystyrene (XPS) foam, which is a lightweight, durable, and thermally insulating material.

Yes, Marmox Thermoblock is designed to accommodate tiling directly onto its surface. It provides a solid and thermally efficient substrate for tile adhesion.

The U-value of Marmox Thermoblock is approximately 0.05W/mK. This low U-value indicates its excellent thermal insulation properties, making it an effective solution for preventing heat loss.

No, Marmox Thermoblock is resistant to mould growth. Its extruded polystyrene (XPS) foam core does not provide a suitable environment for mould or mildew to thrive. Additionally, the waterproof and moisture-resistant properties of Marmox Thermoblock make it an unfavourable substrate for mould growth. However, it's important to ensure that the surrounding materials and installation methods are also resistant to moisture to maintain a mould-free environment.

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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