Quantitative Reliability Analysis of Mitigations Against Construction-Stage Wetting of Cross Laminated Timber Roof Structures

Abstract

The built environment produces about one third of global CO₂ emissions, making rapid decarbonisation essential. Timber buildings could significantly reduce these emissions, yet recent failures caused by moisture intrusion during construction have led to timber decay. Despite broad recognition of the issue, designers and contractors lack quantitative guidance, relying instead on incomplete and anecdotal recommendations. Real construction projects are too complex to replicate in laboratories, creating a shortage of scientific evidence, while valuable industry knowledge remains fragmented and underused. This study introduces a structured expert‑elicitation method that weights expert opinions by calibration performance. A panel of leading industry experts evaluated 19 commonly recommended construction‑stage moisture mitigation strategies. The method offers greater rigour, accuracy, and transparency than standard surveys. Results show, for the first time, that several widely endorsed measures perform poorly in practice or impose major design, cost, or time burdens. The findings provide new evidence to improve design guidance and strengthen moisture‑risk decision‑making through objective identification of effective mitigation strategies. This will support more reliable outcomes and help ensure the safe expansion of timber construction as part of broader decarbonisation efforts.