FAQs
Underpinning FAQs
Underpinning is the process of supporting or strengthening the foundation of an existing house, building or similar structure. This is accomplished by reinforcing the existing foundation, strengthening the soil by introducing an expanding filler, or extending the foundation so that the load is distributed over a greater surface area.
For most homeowners, underpinning is required when the original foundation is not strong enough to support the house. This is usually a result of:
the soil supporting the foundation has changed in some way e.g. through subsidence, expansion/contraction due to moisture, large trees nearby, damaged plumbing left unrepaired.
the properties of the soil were not adequately understood during the original design of the foundation - meaning the foundation is not adequate for the conditions.
In less common cases, underpinning is also required for the following reasons:
The way the structure is used has changed e.g. following a major renovation
New construction nearby resulting in the excavation of soil supporting existing foundations
To increase the capability of existing foundations e.g. to support another storey to the building
Natural disasters such as earthquakes, floods or droughts that have caused the structure to move or become unstable.
To help understand if and when underpinning is needed, let’s take a closer look at the key elements that impact a foundation.
There are some indicative signs to look for when doing a DIY evaluation of your own property. When reading through this list, it is important to understand that subsidence occurs on many properties to varying degrees. Underpinning is only required where subsidence is actively occurring. Sometimes after subsidence initially occurs, the structure reaches a state of equilibrium and there is no further danger. As always, if you are unsure, it is best to ask a professional - which is why we provide a complimentary Home Checkup service.
The answer to this will ultimately depend on the soil your home is sitting on (the site classification) and the type of underpinning service you choose to remedy your problem.
Not all types of underpinning are suited to all foundation problems. When we do our complimentary home checkups, we let you know up front if our method of underpinning is able to provide a permanent fix for you. If not, we won’t quote you and will recommend an alternate course of action.
The reason we exclusively use screw pile underpinning is because it is the most reliable underpinning method available.
Answering the question of “how much will it cost to underpin my house” is similar to asking “what will it cost to renovate my house?”. It depends on a number of variables that can result in significant variance in the cost. Most foundation repairs range in cost from $5,000 to $35,000. In cases where major works are required, the cost can be in the range of $40,000 - $80,000.
When it comes to underpinning costs, the key things to consider are:
What type of foundation do you have?
What is the root cause of the foundation problem?
How extensive is the problem and damage to foundation and home?
How easy is it to access the foundations?
General FAQs
When we do our Home Checkups, one of the things we do is determine if a structural engineer (aka forensic engineer) is required to do a more detailed assessment of the site. We have our own structural engineers we use, so you don’t need to ring around to get separate quotes.
If you have any uncertainty, why not book in a Home Checkup with one of our experts. Or if you just want to pick our brains a bit, then pick up the phone to us now. We will be more than happy to help.
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