Humans and robots increasingly work collaboratively in work environments. Their synergy varies between simple co-existence, wherein they perform independently in shared spaces, to deep collaboration, wherein the joint outcome of their co-working cannot be attributed to either one of the two types of actors alone. Relevant concepts are that of human agency, when robots operate under human oversight, with humans assuming control in appropriate circumstances, and sliding autonomy, where control slides back and forth between humans and robots, depending on the situational context. This study introduces an ontology framework for human-robot interoperability (HRI) in dynamic construction environments. The ontology serves as a context model, facilitating task allocation and collaboration between humans and robots under a Construction Sliding Work Sharing (CSWS) scheme. While previous ontology designs focused either on aspects of construction processes or human-robot collaboration, the ontological formalization of the intersection of HRI and dynamic construction environments is unexplored. The CSWS ontology integrates human-centricity, dynamic task distribution, and human-robot interoperability concepts in construction settings. The ontology development process combines concepts distilled from qualitative content analysis of a construction case study with relevant concepts from previous literature and ontologies. The ontology is consistent with the Sliding Work Sharing (SWS) concept, an extension of sliding autonomy for dynamic task allocation across human and robot actors. The capacity of the CSWS ontology to support dynamic task allocation and human-robot collaboration is exemplified via use cases querying for agent safety, process errors, and human-robot collaborative activities.