Circular Economy is a crucial factor in addressing sustainability. It is also on top of the agenda of the European Union and at a global scale. For Circular Economy to be successful in the construction industry, however, standardisation is a vital requirement. This document refers to an overview on the need for standardisation in Circular Economy. It further refers to national level standards and standardisation, together with a review of European and International level standards. To this effect, following a review of the state of the art in standardisation, key components were identified, and a questionnaire was designed and conducted across 19 countries with experts and practitioners in Circular Economy in Construction. The objective of the questionnaire was to assess and understand the level of implementation and standardization of Circular Economy across different countries. The assessment conducted was intended as a review of the perception of standards and their implementation across Europe by the participants of the survey as practitioners in Circular Economy. A review of standards in Circular Economy at a European and International level was carried out to define gaps to be addressed, together with opportunities in standardisation, to support Circularity in the Construction Industry. Case studies in implementation of standardisation are presented with respect to Deconstruction, Recycled Aggregate and Reuse of products.