Sylfaen® Foundation System


Sylfaen® Insulated Foundation System

Simply put, Sylfaen is the Welsh word for a foundation. 

Tŷ-Mawr’s Sylfaen® Insulated Foundation Systems allow for the use of a reinforced concrete slab or, if preferred, a limecrete slab (as used in the extremely successful sublime® system). Sylfaen® is an Insulated Foundation Systems use Glapor’s® high performing SG 600 100% recycled foamed glass gravel (RFG) to construct a load bearing, thermally insulated foundation – a simple, fast, construction that offers substantial time advantages as well as high insulation values and potential cost savings.


Ty-Mawr has developed a system using Glapor® Gravel as an insulating hard-core for use in foundations. Insulation is provided directly by the SG 600, and the greater the depth of the SG 600, the greater the insulation value. It is easy to insulate to Passive House (Passivhaus) standards using this high-performance gravel from Glapor®. If necessary radon gas protection can be provided by the use of a radon barrier or ventilated sump. Please check requirements with your local area Building Control Officers. As Glapor® is free draining, the examples shown do not include a damp proof membrane (DPM). It is possible to include a DPM if desired, depending on local ground conditions


As can be seen in the diagram below, a reinforced concrete slab (limecrete is too weak for this purpose) is placed on a bed of compacted Glapor® Gravel. As Glapor Gravel can withstand a compressive force of 60 tonnes per square metre it is possible to construct a 5-storey building using this method. Sylfaen® has been rigorously assessed by Structural Engineers, Price & Myer. They were given the brief of assessing Sylfaen® in the worst soil conditions possible for use, their assessment is available on request. All sites should be assessed on a case by case basis by a structural engineer before construction starts.


 Advantages of Glapor

• Best in class- Glapor®’s highest performing gravel product.
• High compressive strength.
• Lightweight.
• Non-combustible.
• Frost resistant.
• Resistant to fungi, mould and rodents.
• Zero capillary action.
• Simplified floor construction.
• Flexible in regards to installation heights, fault tolerant.




  • Insulated foundation systems
  • Insulated flooring systems
  • Landscaping, roof gardens
  • Drainage
  • Lightweight hardcore for road decks
  • Insulating pipe trenches for liquid natural gas, etc
  • Lightweight tunnel backfill


  • In 1 m3 bags as standard, 1.5m3 and 3m3 on request
  • Walking floor lorry 92m3
  • No other insulation materials are required when using Glapor®
  • Glapor® Gravel is made from 100% post-consumer recycled glass.
  • 96% of everything put into a glass recycling goes to make new glass products. 4% is rejected as not commercially viable and would go to landfill. Glapor® is made from this rejected 4%.
  • The manufacture of Glapor® prevents 32,000 tons of waste glass ending up in landfill.
  • It has been calculated that a glass bottle put into landfill takes between 1 and 2 million years to biodegrade.  

To see our brochure please click here, for LABC Registered Details click here.

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