Research into the organisation of building project information began to bear fruit in the 1950s when the first classification system for the construction industry was introduced. Driven by the growing use of digital tools and technologies and by the first publication of ISO 12006-2 in 2001, this research topic has become incredibly popular in recent years. However, the absence of accurate historical traceability in the literature makes it difficult to understand the origin and evolution of the most prominent classification systems. The aim of this paper is to provide a comprehensive review of selected commonly used classification systems published in the last seven decades, delving into those developed in Sweden, the UK and the USA/Canada. Furthermore, the latest classification system launched by each of these countries (CoClass, Uniclass 2015
and OmniClass®, respectively) has been chosen to analyse, compare and discuss its strengths and weaknesses. The results of this research show that there is no consensus on the use of a common international classification system for the built environment. Although organisations worldwide are working diligently towards an internationally accepted standard classifier, the use of national classification systems still prevails. The main gaps to be bridged in this area are discussed in the paper and can be summarised as follows: (i) barriers are found to classify construction elements of residential buildings in a consistent, unambiguous and standardised manner, (ii) commonly used classification systems are designed so that the information required is acquired during the design and construction stages, and (iii) further work is needed to address the challenges of properly classifying construction elements at the operation and maintenance stage.
