This paper reports on experimental research on the long-term performance of block-laminated timber elements. Such elements consist of various glulam beams glued together and are increasingly being used in bridges with restricted construction height. In the presented project, a laminated timber block at structural scale was subjected to controlled variable climatic conditions. Moisture contents, temperature and strains at different points along the length, width and depth were continuously monitored. The paper addresses the following questions: i) which equilibrium moisture content is reached after what period of time, ii) what are the differences in moisture content changes along and across the elements, and iii) which dimensional changes are caused by these changes. First results clearly indicate that assumptions on moisture induced stresses based on the extrapolation of available data from smaller elements are not adequate. These findings will help to assess the impact of moisture content changes on the capacity and serviceability of timber bridges using block-laminated elements.