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Elevator Pits

Mountain Grout Strong

Hydraulic elevators have a piston that goes up and down depending on your destination, Men’s Shoes or Household Goods. That means there is a large hole in the floor of the shaft that often leaks from hydrostatic pressure or wet/dry cycles.

More often than not, newer construction is CMU blocks with a thousand places to leak. Yes, there was a waterproofing membrane or other material installed at original construction, but now it leaks and its 20 feet below grade. See CMU Block page for installation tips. Poured concrete shafts are easier to address. If it’s a crack or cold joint it is managed much the same as simple crack injection (see crack injection). If the issue is poorly vibrated or honeycombed areas, the proper procedure is to drill through the wall and pump the resin to the outside of the structure. If the area is small and specific drill at an angle to cross the zone, place a packer and pump at 250+ psi. The grout will surface almost immediately as the area is likely “rubble” with many leak paths. Still, this method is worth a try and would use far less grout than a large grout curtain.

CMU Construction

CMU construction poses more problems and will certainly use more material in the sealing process. Typically,the leaks are at the mortar joints and when one is sealed, the water moves to the next available exit point. Drill into the mortar joint with a 3/8” bit, set a tap-in packer (3/8”) and pump. If the leak is active, 5 GPM or more, use extra MG Accelerator with the base resin to initiate a faster reaction time. Packer spacing is every two feet in a diamond grid pattern, if possible.

The hydraulic cylinder casing is another area that is susceptible to water intrusion. The most commonway to approach any floor leak is to pump below the slab. Drill directly through the floor, set a packer and pump the resin. If the leak is active add more accelerator to the grout up to 5% or two pints per five gallons. Care should be taken to not over pump the resins, the expanding grout could potentially lift the floor. It is always helpful to leave at least one bore hole without a packer to allow for the release of gas created by the chemical reaction, thus decreasing your chances of lifting the floor.

This is an elevator shaft in Uruguay. The concrete was poorly consolidated allowing water to enter. Water would equalize approximately 4 feet from the floor. Repair was carried out with a small hand pump and approximately two gallons of Mountain Grout Flexible. Resin choice depends on specific site conditions – call us now for advice on your best choice!


  • Mountain Grout HL-100 TDS
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  • Mountain Grout Flexible TDS
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  • Mountain Grout Gel Foam I TDS
  • Mountain Grout Gel Foam II TDS
  • Mountain Grout Ultra


  • Mountain Grout Resin of Choice
  • Mountain Grout Pump
  • FlushInjection Pump
  • High Pressure Injection Gun with extra couplers

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Green Mountain Grout International LLC, Member of the ICRI & Member of the ASDSO.