In the steady-state operation the life-time performance of functional and structural materials in fusion reactor DEMO will be limited by several processes such as a sputtering erosion, transient events and neutron irradiation. The design strategy is to determine the structure and coating thicknesses which maximize component lifetime against all lifetime limitations. The sputtering erosion of the first wall tungsten armor layer due to the plasma impact during the steady state DEMO operation is considered here. It is shown that for DEMO conditions the total sputtering erosion of W armor by the charge-exchange DT neutrals could at least reach~1mm during one year of steady-state operation.
