Ontologies have a place in knowledge sharing with their ability to capture real world information in a machine readable environment. Their application varies from any approach structured on ontological commitment to meta -level ontologies serving for variety of purposes. This variety continues also in methodologies for constructing the ontologies. There are wide range of ontologies differing in size and complexity that are created with different design criteria. The main point with the ontologies is their structure and ability to serve for the intended purpose. This is only granted with the continuous evaluation of ontologies in the construction process, and also before release or reuse of the ontology. Ontology evaluation methods cluster around two concepts such as verification methods that ensure the structure of the ontology, and validation methods that examine their applicability in real world. In light of these, different approaches as quantitative and qualitative methods are depicted in literature from subjective evaluations by experts to tools, all of which investigate different characteristics of ontologies. Objectives of this study are to underline the importance of ontology evaluation and to present an employed validation method used during ontology development for delay analysis. In this context, first; literature review on ontology evaluation is presented. Second, a delay analysis ontology is introduced with its basics to lay the foundations of the study. Cases taken from the Turkish construction industry are exemplified to explain the utilized ontology validation process. Comparison of the concepts in the constructed ontology with the expert reports written for each case is used to evaluate the ontology. Furthermore, alternative validation techniques are discussed as well as possible attempts to keep it responsive and up-to-date. (C) 2014 The Authors. Published by Elsevier Ltd.