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Home built on cut and fill site in The Gap no longer sliding
Our Brief
This single storey house built in the hilly suburb of The Gap in Brisbane had been in a perfectly stable condition for decades. However, just over the last 5 years, the owner noticed significant movement of his home in the ground.
The owner contacted dozens of builders and contractors to determine what was going on. None of them were able to give him a definite reason for his home’s movement.
Years of stress and uncertainty eventually led the owner to finding us. He needed our help to determine if his home was in danger and if the movement could be stopped.
Our Challenge
On arrival, we were able to determine a variety of factors that had led to the shifting of our client’s home.
Firstly, the building had been constructed on a cut and fill site. Cut and fill sites are common in hilly areas like The Gap as builders are unable to construct homes on slopes. Land is cut from a slope and used as fill to create level ground on which to construct a building.
However, the ground was reclaimed land which isn’t particularly solid or stable.
To retain the cut and fill site, the original builder constructed a timber retaining wall at the rear side elevation and at the front of the plot. The timber retaining walls had failed causing the land to suddenly slip.
To add insult to injury, our client’s home had been built on top of a concrete slab poured directly against the unstable reclaimed land. This is a common building technique used in Queensland.
As the cut and fill site slipped, so did the entire slab and the house on top.
Our Solution
Voids underneath the house towards the rear elevation of the cut and fill site were so great that we could put our hands and arms straight into them.
This was a clear indicator the slab on which the home was sitting had slipped so much it was starting to bend. Left unremedied any longer, the structure’s brickwork would have begun to crack. The concrete slab might have broken too.
By injecting our proprietary geopolymer resin, GeoPoly™, underneath the concrete slab, we were able to fill voids in the reclaimed land and seal it. This stabilised the gorund, stopped the movement of the slab and raised the house back to its original level.
The Outcome
The owner of the home had been given insanely high quotes — just to investigate — by uncertain builders for years.
With our expertise, we were able to determine the source of structural problems within a few hours. The cut and fill site, the reclaimed land and the concrete slab. In two days, our client’s home was stabilised and re-levelled.
By restoring his home back to being a safe, stable structure to live in, we helped our client eliminate years of stress without hurting his wallet.
