Generally they are a ball type material made of expanded clay that is mixed with Cement then pumped or barrowed to the location where a skilled operative will install to the required depths.
Lightweight Screed is also available prebagged just requiring water and laying.
A Popular type of Lightweight Screed is Lytag which can be delivered loose or bagged. This option requires mixing with the correct amount of Cement for the floor design. It can be used in Structural Concrete or as a void filler.
Lytag or Lightweight Type Screeds are commonly used on Roofs where they can be laid to a fall and then covered in an Asphalt or Felt. They offer up to 80% less weight than a Traditional Concrete or Screed and help with the Thermal Insulation.
When used in void forming within a Floor, Lightweight Screed will require a very thin Screed Topping that is installed monolithically. This is made from Sand and Cement at a 1:4 ratio. This Topping can also be installed in a Rapid Drying Screed allowing work to carry on.
