Written from the 1970s onwards, Roofs collects practical information (tested for UNESCO by the author himself) on the construction of roofs and shelters, which were intended to meet the material needs of the poor in the global South. It consists of manuals written independently of each other, and is happily representative of the maturity of Friedman, who in those years had already decided to focus his interventions on how to include the inhabitants in the design of their habitat, because "participation is not spontaneous and cannot be claimed out of the blue." While Utopies réalisables (literally, "Achievable Utopias," 1975 - no English edition to date) represents the theoretical summa of this intense period, the manuals are the main communicative tool the Franco-Hungarian architect created, which was aimed at making such utopias concrete. The manuals are composed of essential "blackboard" sketches, which can also be read and interpreted by illiterate people - a feature that convinced Indira Gandhi to print a large number of copies, and also contributed to the establishment of the Museum of Simple Technology founded by Friedman in Madras (currently Chennai), in the mid-eighties.