Circular Economy (CE) is proposed as an solution to the problems the world is facing concerning global warming and resource scarcity. The construction industry however struggles with the new concept of CE. Practitioners lack knowledge, experience and examples. Therefore, embedding circularity in the contract may work as a stimulation. The purpose of this research is to determine a list of requirements on how the client can embed circularity in official documents of infrastructural commissions in an integrated contract in such a way that the contractor can understand, relate and implement the concept in the commission. The results of the research should answer the main research question: What requirements, according to the contractor, do clients of infrastructural projects have to uphold in embedding circularity in the official documents of their commission to stimulate the contractor in implementing circularity in the project? The intention of this research is to form consensus amongst contractors concerning which re¬quirements are necessary for the client to uphold and include in the contract in order to stimulate the contractor in implementing circularity in the project to its fullest potential. To reach consensus, the Delphi-method is applied, which consists of three rounds in this research. The first round is the scoping round in which semi-structured interviews were held with contrac¬tors and clients. From the first round, six themes in which participants encounter struggles with CE were identi¬fied. The second round was a questionnaire in which contractors are asked to judge statements, which were drafted based on six themes from round one. General statements were used as a validation for the six themes identified, example statements were used to determine how currently embedded circularity is perceived by contractors and which improvements have to be made. Moreover, contractors were asked to pro¬vide arguments that support their judgement. Statements on which no consensus have been reached were questioned again in round three. Along with the statements, the arguments given by contractors in round two were provided as well. These arguments enabled respondents to revise their judgement, which is necessary to reach consensus on more statements. The Delphi-method ended with round 3. From the 29 statements, 23 have reached consensus after the third round of the Delphi method; 6 statements did not reach consensus. From the arguments given, combined with the results of the questionnaire, it became clear that in general, clients need to adhere more to the tender-requirements stated by the European law. Concerning the answer to the main research question it becomes evident that clients need to be clear about the by them used definition of the concept of CE. Moreover, direction and scope is appreciated. Award criterion are better for stimulation and a more objective measuring method is necessary. Collaboration is necessary for finding the best solution possible.