Retaining Wall Inspections
In the excitement of inspecting your potential dream home it’s easy to focus on the house itself. You might have cast a cursory glance over the garden and outdoor area. You might even have admired a nicely landscaped garden around a rock retaining wall. But unfortunately these aesthetic touches sometimes conceal a major money pit or potentially deadly hazard. A teetering, unstable retaining wall or a hastily and poorly-repaired retaining wall may be lurking under a foliage disguise. Retaining wall inspections identify any faults in retaining walls that could lead to harm.
Retaining walls aren’t there for their good looks. They perform a number of critical functions. For that reason, if a retaining wall is unstable, the consequences can be disastrous, even deadly. When you gleefully accept the keys to your new property you’re taking on the responsibility of ensuring that your retaining wall is stable and safe. Getting a retaining wall inspection can set your mind at ease and assist you to avoid a financial nightmare.
Having received a pre-purchase inspection which has identified the presence of retaining walls, there
are a few questions that could have significant financial implications, including:
● Who is responsible for retaining walls?
● How high can a retaining wall be without council approval?
● At what height does a retaining wall need to be engineered?
● What causes a retaining wall to fail?
● How do you stop a retaining wall from failing?
Who is responsible for retaining walls?
As a prospective homeowner, it is imperative to ensure that retaining walls are inspected prior to
purchase as you could be the party responsible for the cost of maintaining the wall. Unlike fences, if the
retaining wall is a boundary retaining wall and shared with a neighbour, the retaining wall is the
responsibility of the property owner who benefits from the retaining wall.
In some instances both parties benefit (one side has cut into the land, and the neighbouring side has
retained fill) and it may be a shared responsibility. This type of wall would often have required council
approval and their records subsequently reflect who “owns” the retaining wall. Where doubt over
“ownership” exists, experts such as geotechnical engineers or surveyors will be required to determine
who benefits from the retaining wall.
Poorly constructed or maintained retaining walls have the potential to fail and pose a significant risk to
health and property, which may not be covered by insurances. Failing retaining walls can involve
expensive remediation costs that will be borne by you if the retaining wall is your responsibility.
How high can a retaining wall be without council approval?
Council requirements around retaining walls will vary between local councils. In the Brisbane City
Council area, approval may not be required if the height of retaining wall is less than one metre above
the wall’s natural ground surface. However, the height of the wall is not the only factor determining
whether approval needs to be obtained, as you can see on the Brisbane City Council website.
A retaining wall inspection conducted at the pre-purchase inspection of a property may reveal
unapproved works that will require retrospective approval. The cost of retrospective approval will likely
include council fees, soil testing fees and engineering and drafting fees and is something you should
consider carefully prior to committing to purchase.
At what height does a retaining wall need to be engineered?
Your local council will stipulate at which height retaining walls need to be engineered. Generally, any
retaining wall above one meter in height will require the services of a structural engineer in order to
gain council approval.
Engineering of retaining walls ensure that the load being retained is properly supported and takes into
account such factors as drainage, soil type, size of the load and more when choosing the type of
retaining wall construction. If a retaining wall inspection identifies walls greater than one meter in
height, the best course of action is to check with your local council as to whether it is an approved
retaining wall. Unapproved retaining walls above one metre in height will require the services of a
structural engineer to obtain retrospective approval.
What causes a retaining wall to fail?
Depending upon the material used to construct the retaining wall, failure can be caused by many
factors. Poor design and construction, poor or no drainage (leading to hydrostatic pressure), soil type,
trees and invasive tree roots, subsidence, pests and instability of soil caused by excavation work on that
or neighbouring sites can all cause a retaining wall to fail. We discuss these issues further below.
A retaining wall inspection will identify whether the wall is failing or likely to be in danger of failing and
whether the additional services of a structural engineer are required to provide a further assessment of
the retaining wall integrity. Depending on the cause, treating the cause of retaining wall failure can
necessitate engaging specialists in their fields, including pest control, arborists, plumbers and drainage
specialists, excavators, structural engineers and soil testers.
How do you stop a retaining wall from failing?
In the worst case scenario, a failing retaining wall may need to be completely rebuilt at significant cost.
Other steps that might be taken to prevent retaining wall failure include a reduction to the wall height,
ensuring proper drainage of both surface water and behind the retaining wall, reinforcing the front of
the retaining wall and extending the footing of the retaining wall, amongst others, all of which will likely
require the use of specialists in their fields.
A retaining wall inspection will assist with identifying whether the retaining wall integrity is
compromised, however, the services of an experienced engineer is usually required to provide an
assessment of the state of the retaining wall, the solutions and the costs of remedial works.
Think you might have a dodgy retaining wall? Book online or call and talk to Action Property Inspections on 1800 642 465 or (07) 3201 2666 and arrange your retaining wall inspections today.