This house in the Launceston area, required a total of 16 underpinnings. The concrete deck at the front of the house had pulled the wall out and had dropped in all areas. The deck was removed to make the work area more accessible and helped make the job more economical. The owner intends to build a new treated pine deck at a later date. The holes were founded on hardpan material at varying depths, ranging from 800mm to 2400mm. This was the main reason for such severe movement.
This house in the Hobart area, had a mixture of brick and timber piers that were sitting on the existing clay, without a concrete pad. We supported the existing floor and removed the sub-standard piers. We excavated and poured new concrete pads and fixed new galvanised steel piers in the concrete and to the timber bearer. Working height for this job varied from 900 mm to 300 mm.
Underpinnings showing traditional bulk excavation, which is our main method for doing underpinnings.
This is the most reliable method and we are happy to provide a 20 year guarantee on all our works. Owners can actually look in the hole and see what the house will be sitting on. Engineers can visually see and check that the new underpinning foundation will be sitting on rock or high kpa bearing capacity. Any floating rocks or hard crust layers can be penetrated and removed if hit during excavation.
This cannot be done with resin injections or steel bar techniques.
Concrete foundations have been the main material for house foundations for many years and will continue to be so. The main reason why houses with concrete foundations have failed, is because they did not have concrete piers put in during construction, or they were not put in deep enough.
In this example, the owner’s freezer and bed had fallen through the floor. Due to the lack of ventilation in the sub-floor area, all supporting timbers had failed due to “dry rot”. Photos of different stages of the job are shown below.