Performance of X-Lam panels in a sports center with an indoor swimming-pool

Cross-laminated timber panels (X-Lam panels) are evaluated for structural applications in Service Classes 1 and 2 conditions. The structural application in Service Class 3 conditions is not allowed, mainly because of (1) the high moisture content expected in timber and (2) some concerns related to the potential change in panels' size when significant moisture changes happen. High moisture contents in X-Lam panels are not advisable, because it will lead to high level of stresses in glue lines. Several European Technical Approvals state the insignificance of the dimensional variations of X-Lam panels due to moisture content variation; however, according to other technical documents, this kind of variation should be accounted for. X-Lam panels are widely used across Europe, but their generalized use in Portugal has just started. The Portuguese first large project was completed in spring 2012: a sports center with a 25 m-long indoor swimming-pool and a gym. Given this non-conventional use of X-Lam panels, a monitoring program was started when construction was completed. The monitoring program aims to evaluate the performance of X-Lam panels in places where high environmental humidity is expected. The major parameters monitored are (1) wood moisture content, to ensure that the X-Lam panels are in Service Classes 1 and 2 conditions and (2) the dimensional stability of the panels, to ensure that no unforeseen stresses will develop in the structure. From the monitoring results already available, it is clear that the X-Lam panels are in Service Class 2 conditions without relevant dimensional variations.