Façade prefabrication in tall CLT buildings: time, cost and operation quality analysis through Building Information Modelling

The present work deals with the quantification of time and cost savings brought about by different degrees of envelope prefabrication for tall cross-laminated timber (CLT) buildings. First of all, the traditional construction practice is analysed as benchmark reference value to outline strategic advantages related to the adoption of a prefabricated approach. Thus, two proposals have been detailed: one requires joint completion at the construction site by acting through lifting platform from the outside of the building, the other is meant to be totally preassembled offsite with no need for action from the exterior. Both of them are based on the principle of scaffold elimination, as it usually happens in the case of tall buildings. The evaluation phase is based on a case study tower building, 9-storey high, implemented in a BIM model to give evidence of the overall construction management consistent improvements. Outputs demonstrate how façade extensive prefabrication concurs in reaching significant time and cost reduction, as well as improved work organization, safety and operation quality levels. This applies particularly in the case of timber-based multi-storey structures, where minimizing exposure to weather agents could become a crucial aspect to take into account during on-site works.