Application of the factor method to the prediction of the service life of external paint finishes on façades

The main goal of this study is to predict the service life of external paint finishes and contribute to the subject of construction elements´ durability. The service life is estimated using the factorial method proposed by ISO 15686, since, despite some criticism, this method excels as a simple and efficient tool with great potential for use in the planning of maintenance operations. The model proposed is based on a field survey of 323 coatings. The factor method estimates the service life of building components by multiplying their reference service life by weighting values applied to several factors affecting the performance of the elements under study. In this study the durability factors are obtained through iterative simulations. The results are analysed based on a set of criteria and statistical indicators. The results are suitable and reliable for most of the deterioration variables considered and the factor method proves to be an efficient tool to evaluate the service life of external paint finishes. This work is intended as a contribution and reference for future developments within the subject of durability in the construction industry as knowledge on the performance of given materials or constructive systems over time allows estimations of when to invest in maintenance/repair and of the amount of resources that will be required.