Conventional Raft Slab

A ‘Conventional’ Raft Slab is a concrete base with thickened beams laid directly on the base.

This photo shows the base covered in poly and with reinforcement in position ready for placing of concrete.


  • Better thermal mass, and incorporates thermal mass of ground  so better suited to passive solar design.
  • Less susceptible to bad workmanship by concretors
  • More resistant to point loads, such as jacking a car.
  • A thicker overall slab makes it easier if you want Floor Drains (To allow for the dropped floor in those rooms)


  • Generally uses more concrete, than ‘Waffle Pod Slabs‘, with more waste as volume is less predictable
  • Trenches excavated in the base, that can fill with rain causing delays
  • More complicated excavation with additional cost


Also see Ground Conditions