It may seem surprising six years after the Canterbury earthquakes that House Lifter owner Rod Moore is busier than ever.
But he said work is ramping up for straightening commercial buildings, while his residential work was also the busiest ever, and he was looking at contracts in Wellington too.
With the increase in contracts Moore decided to invest in a synchronous computer-controlled hydraulic jacking system from Netherlands company Holmatro.
The cost to excavate and lift the concrete floor of the 340-tonnne building at Ferrymead, Christchurch will be about $500,000, and the cosmetic repair might take the final cost to about $2 million – compared with demolition and rebuilding for about $5m to $6m.
“There are other similar jacking systems but they’re big and require trucks to bring in all the gear whereas this is small and I only need a few guys.”
“I went to the Netherlands to meet engineers at Holmatro and visited the factory.
“Two engineers came out to New Zealand to help me get things going. They were also going to talk with KiwiRail about lifting derailed trains.
“It’s our second job with the gear and after three days we’ve lifted it 200 millimetres to re-level. All the gutters run correctly now.
“We take pre-level surveys and mark out the jacking points. Digging the pits for the jacks is hard work and then we tunnel under the edges of the building so we can pour jacking pads with reinforcement under them.
“After placing 25 jacks, we connect the hydraulic pumps and the wires to measure the heights and then it’s all connected to the computer.
“With other systems you need several guys to go around all the jacking points and try to raise them simultaneously.
“This monitors all the points at once as the building is slowly lifted and if there’s a problem like a jacking support being squashed it alerts you and stops so nothing breaks.”
Once the building is raised to level, sacrificial props are placed underneath with the assistance of sledgehammers and the voids underneath are filled. The final job is to run a radar test to detect any gaps.
The centre of the floors are also monitored for sagging and a beam and screw system can lift areas that need it.
Imperfections in the original concrete floor often show up.
“We try to get it back to the original pour of the slab. We’re within 0.1mm now.
Holmatro had used the system for unusual projects such as re-leveling the Netherlands parliament buildings and a castle, Moore said.