The integration of a genre-based and a corpus-based instruction in ESP learning (Swales, 1990; Tribble, 2000; Ferguson, 2001; Flowerdew, 2005) has proved to be a suitable theoretical framework for describing the lexis of construction and architecture university textbooks, such as the sample compiled in the Construction Textbooks Corpus (CTC). This paper is a contribution to the study of the formal and semantic profiles of the lexis of this particular genre type and, by way of illustration, focuses on the case study of the lemmas build and construct. From a formal standpoint, the CTC reveals that the noun building (the first content word in the CTC) is six times more frequent than the verb build, and the noun construction (third in frequency) is eleven times more frequent than the verb construct. Semantically, the corpus displays a prevalence of technical meanings which refer to building and construction as the activity or business of erecting edifices or structures. By observing the lexical profile of construction textbooks, this paper will finally consider possible teaching/learning implications.