As time as progressed, as have the machining methods of solid oak flooring. This has led to the incorporation of grooved undersides (or stress grooves) into much of the modern day oak flooring. Grooved undersides are small grooves which have been cut into the bottom of the oak board, and usually measure at just a few millimetres in depth.
These grooves are specifically designed to reduce the natural tension of the boards, taking out the pressure. Rather than just one single large groove, a series of grooves are cut, the number of which depending on the width of the board. The incorporation of these grooves help to improve the overall stability of the boards.
Further to this, stress grooves are also designed to help to reduce the possibility of your solid oak boards from cupping. Known as the opposite of crowning, cupping is a condition where the centre of a board is lower than its edges. This creates a concave appearance across the board, which is normally created when moisture is present.
Due to the construction of engineered oak boards, stress grooves are not needed. This is because engineered boards will cope with any moisture much better than solid boards, making it a popular choice for use inside kitchens and bathrooms.