Multi-Unit Lifting & Levelling
Problem: Due to earthquakes, the large building (five, two-storey units and five garages), needed re-levelling. The weight of the building when floating on the Hydraulic Jacks, was approximately 618 tonne.
Solution: The front four units and west wall of the fifth unit, were re-levelled using ‘Jack and Pack’ for the perimeter foundations and walls. The reinforced concrete ground floor slabs were re-levelled using steel trusses, and threaded steel rods were temporarily set into the floors.
Prior to re-levelling, the Geotechnical Report showed the floors had a Level difference of over 100mm, and Grades in excess of 1.6%.
The floors were re-levelled to within 7mm within the units (±10mm within the garages). Evidence before re-levelling showed the floor levels varied considerably prior to the earthquakes, so the ground floor after re-levelling was considered to be more level than it ever was.
After the floors were re-levelled, grout was pumped through holes in the floors to fill cavities below, and the filling checked by GPR: ground-penetrating radar, to ensure there were no cavities left unfilled below.
“Being in the building industry, I knew what could go wrong if I didn’t choose the right company for the job. When Rod saw the house and looked at the plans, he was confident about what needed to be done, and enthusiastic about the challenge. But the other contractors who I got quotes from, either I could tell that because the lift was so complex, they didn’t want to do it (and their price reflected that)… Or their methodology of how they were going to do it, didn’t give me confidence. The lift went well and House Lifters were very efficient at providing information and documentation to the Engineer. The ‘close-out’ paperwork was sent quickly too.”
Matt Russell – Homeowner