Because it offers good milling properties, especially for self-locking tongue and groove, medium- and high-density fiberboard (MDF and HDF) have gained acceptance as a substrate in the manufacture of engineered wood flooring (EWF). Depending on the component selected, delamination in the fiberboard or severe cupping deformation have, however, been observed. The aim of this study was to identify key design parameters in EWF made with MDF and HDF substrate, taking into account the density of the fiberboard, the characteristics of the face layer, and the type of backing process selected to meet quality requirements. A sliced face layer led to lower cupping deformation than a sawn face layer. With a sawn face layer, denser HDF provided a better substrate for EWF. The use of melamine-impregnated paper as a backing layer significantly contributed to reduced cupping deformation in all cases.