In heterostructures with thick spacer layers the random potential in the channel created by remote impurity ions is smooth and can be treated classically, so that a percolation interpretation of the metal ‐ non‐metal transition (MNMT) is possible. The critical electron density,ncof the MNMT is found as a function of the spacer width and the ion density. The connection between the critical densityncfor the transition without magnetic field and the width of the plateaus of the integer quantum Hall effect (IQHE) in a sufficiently strong magnetic field is established. The width of the plateau as a function of spacer thickness and magnetic field is discussed.