There is a continuous spectrum of wood-based products within a density range of 200 to 1000 kg/m3 produced by the wet-process method of fibreboard production: for convenience, these are classified into three groups, traditionally known as softboard, medium board and hardboard. Within each group, boards of differing densities are produced, each finding a set of applications either within or outside the construction field. While a number of applications have now been lost to medium density fibreboard (MDF), wet-process fibreboard is still manufactured in considerable quantities in a number of countries. This Digest describes wet-process fibreboards and provides guidance on their use when manufactured to the European Standard EN 622 Parts 1 to 4. It demonstrates how, when the product is used in construction within Europe, mandatory compliance with the Construction Products Directive can be achieved by using the new European Harmonised Standard (EN 13986). 8 pages.