Standard methods for measuring the moisture diffusivity te of porous materials are based on determining the spatial moisture distribution at the specified time levels mostly, and require rod specimens. Therefore, these methods axe suitable partic-ularly for isotropic materials and inapplicable for board materials where the ani-sotropy in at least two directions, along and across the board, is to be taken into account. In this paper, we present two methods for determining the moisture diffu-sivity in the direction across the board where it is currently not feasible to measure the moisture distribution with sufficient accuracy. The first method is based on Boltzmann transformation with a fixed spatial point (BTX method) while the sec-ond one consists in the assumption of piecewise constant moisture diffusivity with respect to the moisture content. Both methods are verified by measurements of moisture diffusivity of two typical building materials, the heat-insulating lining ma-terial Dekalux and heavy concrete for nuclear safety related structures, the results axe compared with measurements by standaxd methods. Measuring results show satisfactory precision and good applicability of the method with piecewise constant r., but reveal significantly lower precision of the BTX method if lower-order approx-imations of moisture distribution and moisture flux are used.

• measurement: vapor diffusion properties, WVT : moisture diffusivity of board materials