Insulated Concrete Form (ICF) is a polystyrene (or similar) formwork filled with concrete and rendered to create a wall. The polystyrene formwork has a high insulation (R‑value) and generally does not require additional insulation.
BASIX calculates the R‑value of the wall based on the thickness of the form and the concrete. These values can be obtained from manufacturers of these wall systems.
Diagram showing a section through an Insulated concrete form wall