In Echallens (Canton Vaud) Dettling Péléraux have transformed the hall of a stone masons’ business into a training facility. Thanks to the north-light roof trusses and aluminium facades the building retains its industrial character, while generously glazed openings suggest its public function. The side halls in this tripartite complex, one of which was already in existence, are used for practical exercises, while the two-story central part houses classrooms, ancillary rooms, and the circulation. The new hall is built in part of materials reclaimed from the site. What were once concrete facade elements are used for internal walls running along the facade, load-bearing timber elements become external roofs, and galvanised steel sheets are re-used as roofing. The restrained, uniform expression of the new vocational school is convincing, as are the figures: more than three-fifths of the building consist of existing elements or are newly built from re-used components.