1 INTRODUCTION A serious problem of the construction of buildings is produced by the need to work at high lev- els. This implies a high risk to workers and increases the cost and timing of the work. Figure 1.Vaughtborg Lift Slab System. Figure 2.Lift Slab System. Much years ago it has tried to get building systems that allow building, usually the structure, at ground level and then to raise the building. Some of the most used has been the lift slab. This is a method of constructing concrete buildings by casting the floor or roof slab on top of the previ- ous slab and then raising the slab up with hydraulic jacks, so being cheaper and faster as not re- quiring formwork and propping for casting in situ. A new building system: Structural aspects of COTaCERO system J. P. Valcárcel Senior Professor of Structures. E.T.S. Arquitectura. A Coruña. Spain. V. Hermo Professor of Architectonical Construction. E.T.S. Arquitectura. A Coruña. Spain. J.B. Rodriguez Cheda Senior Professor of Architectonical Construction. E.T.S. Arquitectura. A Coruña. Spain. ABSTRACT: A great problem for the building construction is the need to work at high level. That is a serious risk to workers and increased cost. The patented COTaCero system, developed by a research group of the University of A Coruña, allows the construction at ground level and the subsequent lifting of the structure. The upper level of the building is the first to be built at ground floor. This level is lifted through hydraulic lifting jacks and a new level is built under it. Subsequent phases allow build the entire building, always from the ground level. This article discusses the structural aspects of the solution. The building structure is com- posed of welded steel plates. These plates define the walls and partitions and themselves are re- sistant. It is therefore not necessary an additional structure. The paper provides the calculations that support the effectiveness of the solution. Complete this paper the experimental results obtained in a series of tests performed within a research project. Structures and Architecture: Concepts, Applications and Challenges – Cruz (ed) © 2013 Taylor & Francis Group, London, ISBN 978-0-415-66195-9 1056