As a consequence of foundation settlement observed in one of the most important buildings of Christchurch – New Zealand, due to the 2010 and 2011 seismic events occurred in that city; repairs have been made enabling the Christchurch Art Gallery building to reach its original level. Building uplift consisted on the use of soil injection techniques, providing “in-situ” soil reinforcement with grout material and an increase of soil volume by soil fracture. This solution is denominated as “jack on grout” (JOG). The present article describes the adopted soil improvement solution underneath the existent building, using jet grouting columns. The mentioned technique has been used to provide an increase of soil stiffness and strength, enhancing sufficient soil reaction under incremental stresses imposed by JOG during the structure uplifting works. In addition, jet grouting was considered to be an added value on long term soil behavior regarding soil induced liquefaction mitigation.