A screed is a construction element that comes in various thicknesses. It's main job is to provide a solid, long-lasting surface for the installation of specific flooring and/or waterproof products.
Screeds are made from sand and cement mortar, or anhydrite-based mortar.
Screeds can also be heated; this usually means a central heating system is installed and screeded over to provide a warm substrate all year round.
In New Zealand, screeds are mainly installed in showers to create the falls necessary for any water to go down the drain.