This study evaluated the applicability of substituting flakes in the core layer of oriented strand board (OSB) with chips from comminuted and unrefined particle boards and wood waste. Results from the analyses show that the applied modification of the core, even at a relatively high proportion of chips (amounting to 75%) makes it possible to manufacture OSB with good mechanical properties, meeting the requirements of the standard EN 300. In contrast, the use of melamine–urea–phenol–formaldehyde resin does not guarantee the requirements (in terms of moisture resistance) will be met.