A case study on the construction of a CLT building without a preliminary roof

Abstract

This paper focuses on cross-laminated timber (CLT) and how it is affected by the dynamic properties of moisture during installation in the cold climate of Estonia. The moisture safety principles are designed using a case study of comparable activities with 4D principles and on-site water content monitoring. On-site water content monitoring was done on the CLT elements that were installed and a parallel polygon specimen. Polygon testing was arranged with reduced size CLT elements subject to different conditions, with some exposed to the climate, some protected from precipitation, and some covered with film.

The moisture content (MC) of the uncovered horizontal CLT element that was exposed to the climate reached over 25% after higher precipitation and the MC after prolonged direct exposure can reach up to 40% in a week, giving a clear signal of high risk areas for moisture safety. Installing a partly weather protected CLT element without a preliminary roof is a high-risk arrangement, but is essentially possible in a cold climate. Moisture safety pre-planning and a lean strategy must be applied with timber construction.