Tuffstone elements with a large length/width ratio often suffer damage in the form of cracks parallel to the surface and spalling of the outer layer. This study aimed at verifying if this damage may be the result of a differential dilation between parts with different moisture content. The research, carried out on Ettringen and Weibern tuff, comprised a weathering test and measurements of porosity, moisture transport and hygric behaviour of the stones, supplemented by environmental X-ray diffraction analyses. Results support the hypothesis that moisture gradients in tuff elements may enhance decay in this stone.