Underfloor Insulation

FoamGlass 65: The Smart Solution for Underfloor Insulation [eco]

When it comes to building or renovating floors, especially where underfloor heating is involved, choosing the right insulation system is critical. Traditional methods often require multiple layers, materials, and time-consuming installation.

That’s where FoamGlass 65 stands out.

Made from recycled glass and expanded into a lightweight, highly insulating aggregate, foam glass offers a modern, efficient alternative that combines insulation, drainage, and structural support in one material.

What is FoamGlass 65?

• FoamGlass 65 is a lightweight aggregate produced from recycled glass that has been heated and expanded to create a cellular structure. The result is a strong, insulating material that is:

  • Lightweight yet load-bearing

  • Highly insulating

  • Free-draining

  • Resistant to moisture and frost

  • Environmentally friendly

It’s increasingly used across construction projects, but one of its most effective applications is in underfloor insulation systems.

Why Use Foam Glass for Underfloor Insulation?

Traditional floor build-ups typically include hardcore, insulation boards, membranes, and screeds each installed separately. Foam glass simplifies this.

With Foam Glass 65, you can:

• Replace hardcore and insulation in one layer

• Improve thermal performance

• Reduce build complexity

• Speed up installation

  
  

It’s especially useful in:

• Renovation projects

• Older or heritage buildings

• Sites with poor or uneven ground

• Areas prone to damp

Typical Underfloor Build-Up Using Foam Glass:

A foam glass floor system is straightforward and efficient. A typical build-up looks like this:

1. Compacted FoamGlass 65

   Acts as both structural base and insulation

2. Blinding Layer (optional)

   Helps protect the membrane and create a smooth surface

3. Membrane (DPM / Radon Barrier)

   Prevents moisture or gas ingress

4. Underfloor Heating Pipes

   Installed above the membrane

5. Limecrete or Concrete Slab

   Final structural and heat-distributing layer

This system reduces the need for multiple materials while maintaining excellent performance.

Key Benefits of Foam Glass in Floor Systems

1. Thermal Performance

FoamGlass 65 reduces heat loss to the ground, making it ideal for use with underfloor heating systems. More heat is directed upward into the living space, improving efficiency.

2. Moisture Control

Unlike traditional materials, foamglass is capillary-breaking, meaning it prevents moisture from rising through the floor. It also allows water to drain freely, reducing damp-related issues.

3. Load-Bearing Strength

Once compacted, foam glass forms a stable, load-bearing layer suitable for domestic and many commercial applications.

4. Breathable Floor Build-Ups

When used with limecrete, foam glass supports breathable construction making it particularly suitable for older or solid-wall buildings where moisture movement must be managed carefully.

5. Sustainable and Eco-Friendly

Made from 100% recycled glass, FoamGlass 65 is an environmentally responsible choice with a low carbon footprint compared to traditional insulation materials.

Installation Overview

Installing FoamGlass 65 is straightforward:

• Delivered loose and spread across the area

• Installed in layers and compacted

• Typically compacted to around 60% of its loose depth

• No need for a perfectly level sub-base

Thickness will vary depending on project requirements, but typically ranges from 150mm to 600mm.

Other Applications of Foam Glass 65

While underfloor insulation is a key use, foam glass is also ideal for:

• Sub-slab insulation in new builds

• Lightweight fill for roads and landscaping

• Green roof systems

• Drainage layers (French Drain)

• Backfill where reduced load is important

Its versatility makes it a valuable material across many types of construction.

When is Foam Glass the Right Choice?

FoamGlass 65 is particularly suited to projects where:

• Ground conditions are poor or uneven

• Moisture control is important

• A breathable floor system is required

• You want to reduce excavation depth

• You’re working on a retrofit or conservation project

Cost vs Value

While foamglass may have a higher upfront cost than traditional hardcore, it replaces multiple materials and reduces labour time.

When you factor in:

• Installation savings

• Improved thermal performance

• Longevity and durability

…it often delivers better overall value.

Conclusion

FoamGlass 65 offers a smarter way to build insulated floors.

By combining structure, insulation, and drainage in one material, it simplifies construction while improving performance especially in underfloor heating systems.

If you’re planning a new build or renovation and want a reliable, efficient floor solution, Foam Glass 65 is well worth considering.

Products mentioned:

FoamGlass 65
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