Application of the factor method to the estimation of the service life of natural stone cladding

Abstract The last few years have seen expressions of concern about the sustainability of construction from all actors in the sector. The durability of the materials used has, in particular, been mentioned as a determining factor in increasing the service life of structures and consequently in reducing energy consumption and environmental impacts as a whole. With the introduction of new products and/or the adoption of new constructive techniques it has become necessary to develop the fields of durability and service life prediction of construction products, with the purpose of evaluating their performance throughout their life cycle. A model to estimate the service life of natural stone claddings is put forward, based on the factor method initially proposed by the Architectural Institute of Japan. This method involves the appraisal of the degradation phenomena in stone claddings under real use conditions, through a field survey. 269 stone claddings located in Portugal were analysed. The factors that affect the durability of natural stone claddings were examined. The quantification of the factors affecting the durability of stone claddings is affected by some subjectivity. Therefore it does not seem viable to propose standard values that can be applied in all circumstances. Analysis of the scenarios proposed for that quantification shows that the use of generic values for durability factors, such as those in ISO 15686:2000, does not lead to the best results. The best solution is to adopt durability factors adjusted to the reality of the phenomenon to be modelled at a regional or local scale. This is a first approach to applying the factor method to estimate the service life of natural stone cladding. It is considered that the method proposed shows very promising results, though it still needs to be supplemented, particularly in terms of the comprehensiveness of the sample.