In relation to the call for investigation held in 2004 in this city by the Iberoamerican Biennale of Architecture and Planning, ten years ago the Experimental Housing Project (Previ), from Lima, awakened renewed interest among young and senior architects who were approaching this experience with the watchful eye of those who want to learn to build social housing with an inalienable urban vocation. Likewise, the unfinished business of industrialization in low-cost housing has led to the study of this case. After setting out the basics of Previ that allow us to understand and project it in context, this article analyzes that experience again in order to understand it from projectual typological keys that, from our point of view, build a bridge between life flowing (the utilitas) and the rigour that rebuilding demands (the firmitas).