This paper presents an approach that aims to suggest to Construction experts a formal representation of given requirements. When available as formal expressions, requirements are suitable for automatic compliance checking. The goal of conformity checking is to answer the question " which components of a building project are non-compliant to a set of construction rules? ". When we consider both the size and the complexity of corpora of construction requirements, a computer-aided compliance checking process would be beneficial for experts. Such checking process requires a formal representation of building projects and construction rules. Nowadays, there are various tools for the formal designing of building products obeying to the Industry Foundation Classes (IFC) standard (e.g. Revit Building of Autodesk, ArchiCAD by Graphisoft, and ACTIVe3d by ARCHIMEN GROUP). On the other hand, to the best of our knowledge, there isn't any tool which allows business experts to convert automatically and in a formal language, construction rules written in natural language. We propose an approach which intends to convert automatically natural language requirements into formal expressions. This approach relies on the IfcOWL ontology and represents formal rules as SPARQL queries using the RAINS language as an interim result. RAINS is a controlled natural language (CNL), whose sentences can be transformed automatically into SPARQL queries, and as a CNL it hides the complexity of formal languages.