Slab on grade

Slab on grade is a concrete slab in contact with soil.

Often, the slab on grade is confused with the foundation slab, which carries the building's load. In the case of slab on grade, the load-bearing function is taken over by strip or point foundations. Depending on the intended use of the space above, the slab on grade may or may not be a structural load-bearing element, and similarly, it may be thermally insulated or left as is.

Most often, slab on grade describes levelling concrete covered with waterproofing and other layers, depending on the intended use of the space (e.g. basement or, in older buildings, residential ground floor). Also, slab on grade is used in industrial flooring, where instead of levelling concrete, a structural load-bearing reinforced concrete slab is poured. Naturally, this implementation is, contrary to the first instance, quite more demanding.

Despite the nearly-zero-energy demands of energy efficiency in buildings, slabs on grade using levelling concrete will continue to be implemented in multi storey buildings with unheated basements, while lower buildings are built on foundation slabs.

Slab on grade assembly

  • final layer (e.g.tiles)
  • cement screed
  • PE foil
  • sound insulation – foamed polyethylene foil
  • FIBRANxps 300-L
  • waterproofing
  • levelling concrete
  • sand levelling
  • gravel
  • compacted (vegetated) soil