This paper reports on the instrumentation, monitoring and some preliminary results from a real-time monitoring scheme of a hybrid concrete-lattice-girder slab flooring system. One of the key benefits of this monitoring project is improved understanding of in situ structural behaviour. Sensors were embedded in both the precast and in situ components of the floor system and were used to monitor various aspects of the behaviour of the floor during the manufacturing, construction and operational phases. Concrete strains and temperatures were measured, while environmental conditions were also monitored to assess their effects on the floor structure. The information from the real-time monitoring offered the opportunity to compare actual and predicted behaviour using structural codes, such as Eurocodes. Results on the early-age behaviour of the floor slab during the construction phase (strain, thermal cracking, restraint factors) are described in this paper.