Abstract: Finite-difference method is proposed for the first time for solving the transient heat and moisture transfer problems in 1-D multilayered building elements.Transient boundary conditions are specified for both heat and moisture transfer at external surfaces, while constant values are assumed for material properties of each layer of the structure and the discontinuity of material properties for each layer is considered.The calculations for a typical three-layer wall are conducted to obtain the dynamic distributions of the relative humidity at the interfaces of every layer during 24 hours by use of the mentioned method,and the results agree with those of the transfer function method which is empolyed in reference[6].The method can be extended to 2-D and 3-D coupled heat and moisture transfer problems.

Key words: porous media, coupled heat and moisture transfer, relative humidity, multilayer