BS8201:1987 recommends that wood flooring is protected from ground water. If installing at ground level or below we recommend that you employ a surface applied damp proof membrane as a standard part of the flooring specification. This is because old buildings may not have an integral DPM, and the integral DPM below screed in newer buildings may be breached now or in the future, resulting in moisture ingress and damage to wood flooring. Hearths must always be damp proofed as these rarely have a damp proof membrane.
If installing at 1st floor level or above (i.e. well above ground level), a DPM may not be necessary. First check the moisture condition of the floor at frequent intervals using a non-destructive method such as Protimeter on search mode, or a Tramex Concrete Encounter, being sure to check any known risk areas such as near exterior walls. Then take the points of highest readings and further test these areas using the 72 hr ‘equilibrium relative humidity’ test method as described in British standards. See: manufacturer details for critical moisture levels. (Further advice on request). If in doubt employ a moisture barrier suitable to the installation method (e.g. Epoxy DPM, polythene membrane etc).