Queensland homes are notorious for experiencing subsidence due to extreme weather conditions and soil characteristics. Therefore, it is not rare to see properties with underpinning. While house stability should be restored through underpinning, it poses other challenges such as insurance cover. Therefore, spotting these signs early will allow you to make a more informed decision when purchasing the house.
To assist you, we’ve detailed below what underpinning is and outlined a few pointers when it comes to spotting subsidence. We’ve also listed a few signs that the house you’re about to purchase has been underpinned.
What is Underpinning?
Underpinning is the process of strengthening the foundations of an existing building. It might be necessary because the original foundations weren’t strong or stable enough, or the usage of the structure has changed. Underpinning can also be a necessity if the properties of the soil supporting the foundations have changed or the structure has moved due to various reasons, including natural disasters, impacting the structure of the property. This often leads to the floor collapsing or sinking, taking the foundations with it (this is called subsidence).
However, in some cases, homeowners use underpinning to lower their floor and create more usable space. By building new foundations under the current foundations, you can lower your floor and create a brand-new room or space.
Note that underpinning can be accomplished by extending the foundation in depth or breadth.
Signs a House has Subsidence
Signs a house needs underpinning include:
Visible cracks in the walls, paths, or driveaway.
Cracks or gaps around the windows or door frames.
Sinking or sloping floors.
The property leans to one side.
Visible tree roots in the home’s walls or around the house’s foundations.
Windows or doors are jammed.
Skirting boards are separating from the wall.
Stagnating water around the home.
Signs a House Has Underpinning
Although rare, if you or your surveyor spot the edge of an exposed concrete foundation at ground level, it means the house has been underpinned.
A surveyor can also look at movement throughout the building. They would, for instance, analyse whether such movement is active and progressive or rather dormant and historic and assess the severity of the movement to determine whether the property has been underpinned.
If you’re aware that the property has been underpinned, the buyer should have all of the relevant documentation, including a certificate from the Structural Engineer, stating that the work has been completed adequately to the industry’s standards, and the house is structurally sound. Make sure you request and review the documents, as they will provide you with insurance for the work that has been done.
The best way to tell if a house has signs of subsidence or if it has been underpinned is to rely on professionals and use their knowledge and conclusions to determine if you should negotiate the price to accommodate for potential fixes or even whether the house is worth buying.
Need help with a potential purchase? At OneHome Inspections, we provide thorough Building Inspection services to help buyers make the right decision. Don’t hesitate to get in touch, as we’d love to help.