English: The structure of 34Si was studied through γ spectroscopy separately in the β− decays of 34Mg and 34Al at the ISOLDE facility of CERN. Different configurations in 34Si were populated independently from the two recently identified β-decaying states in 34Al having spin-parity assignments Jπ=4− dominated by the normal configuration π(d5/2)−1⊗ν(f7/2) and Jπ=1+ by the intruder configuration π(d5/2)−1⊗ν(d3/2)−1(f7/2)2. The paper reports on spectroscopic properties of 34Si such as an extended level scheme, spin and parity assignments based on log(ft) values and γ-ray branching ratios, absolute β feeding intensities, and neutron emission probabilities. A total of 11 newly identified levels and 26 transitions were added to the previously known level scheme of 34Si. Large scale shell-model calculations using the SDPF-U-MIX interaction, able to treat higher order intruder configurations, are compared with the new results and conclusions are drawn concerning the predictive power of SDPF-U-MIX, the N=20 shell gap, the level of mixing between normal and intruder configurations for the 0+1, 0+2, and 2+1 states, and the absence of triaxial deformation in 34Si.