GLAVEL - Foam Glass Gravel

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Product Specifications

For sales information, please reach out to Glavel directly. 475 had a hand in the founding of Glavel: the first company to make foam glass gravel/aggregate in North America with an electric furnace - powered solely by renewable energy. This product is a much preferred Smart Enclosure alternative to foam under your slab.


As a load-bearing, thermal insulating substrate under a slab, glass foam offers a combination of properties that no other material can offer. GLAVEL replaces the aggregate layer (drainage/capillary break under slabs), the frost barriers and provides thermal insulation from the soil. This provides a simple, thermal bridge-free soil structure for a thermally separated slab in one step.


Ships in 3.5 cubic yard bags (2.7 m3)


  • The large number of closed-cell pores create excellent insulation value
  • Very water permeable, interstitial spaces allow water to drain off
  • Excellent frost resistant properties and protection against frost heave of foundations/roadbeds
  • Lightweight, bulk density of foam glass is only one twentieth of the other weight of aggregates
  • Resistant to nearly all acids, bases, bacteria, frost, aging, rotting, wetness and rodents
  • Environmentally-friendly recycled glass has an excellent energy balance
  • Inert material when exposed to soil, qualifies as “clean fill”
  • Non-combustible, glass does not burn


  • R-value: 1.7 per inch
  • Thermal Conductivity λ : ≤ 0.048 BTU/h*ft*F
  • Low specific weight: 9.5 lbs./CF (bulk volume)
  • Compressive Strength f (deformation = 10%): ≥ 116 psi
  • Compressive Strength f (deformation = 2%): ≥ 54 psi
  • Loose Bulk Density (1.3 : 1 compacting): 85 - 95 psi/1000 ft
  • Minimum Installation Thickness: ≥ 5.9 inches