FOAMGLAS® Insulation for Use Below Ground
Insulating below ground structures requires a material that can withstand challenging conditions – from high structural loads and persistent groundwater to brownfield sites and the need for consistent thermal performance.
Lifetime Performance Where It Matters Most
Below Ground
Climate change is reshaping the way we build. Rising groundwater, heavier rainfall and shifting soils are increasing risks for below ground structures – especially in commercial buildings, where insulation must perform reliably for decades. Once installed beneath the foundation, it cannot be replaced, making long-term durability and resistance to environmental stress essential.
Discover how FOAMGLAS® insulation delivers consistent thermal efficiency, high compressive strength without deformation, and long-lasting performance – making it a future-proof choice for below ground applications.
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* EPD-PCE-20200300-IBB1-EN, published by IBU. Third party verification upon request.
Applications
for FOAMGLAS® Below Ground Insulation Systems
FOAMGLAS® products offer versatile solutions for below ground insulation, catering to different project needs and specifications. The primary applications include:
FOAMGLAS® boards and slabs can be installed either as a single or double layer, loose laid or fully bonded system beneath the ground floor slab. This method provides a continuous insulation layer, enhancing thermal performance and structural integrity.
Technical Data sheets
For external wall insulation applications, FOAMGLAS® products can be applied with a combination of adhesive and / or special mechanical fixings, depending on the project requirements. This approach ensures a seamless thermal barrier, protecting the structure from the effects of thermal bridging and moisture ingress
Technical Data sheets
When internal insulation is preferred, FOAMGLAS® cellular glass offers bonded or loose laid solutions that maintain the thermal line inside the building. This method is particularly useful for retrofitting existing structures or when external insulation is not feasible.
Technical Data sheets
Where internal insulation of below ground walls is required, FOAMGLAS® boards and slabs are positioned and secured using both adhesives and special mechanical fixings. Use in conjunction with cavity drain waterproofing systems and a variety of internal finishes are additional benefits.
Technical Data sheets
Download our whitepaper
to explore the structural advantage
WHAT BUILDING PROFESSIONALS SAY ABOUT BELOW GROUND INSULATION*
In a quantitative questionnaire conducted by the FOAMGLAS® team, around 300 architects and engineers were asked about current trends.
Here is how they see the future of construction:
Industry Trends
Agree insulation should last the lifetime of the building.
Recognise recycled content as a key factor in insulation materials.
Recognise that climate change is increasing risks such as groundwater rise and soul movement.
*Insights based on a quantitative questionnaire with 300 architects and engineers, conducted by Owens Corning (May 2025).
