Dangers of retaining wall movement.
Retaining wall movement dangers. By Peter Weddell, owner/operator of Qld Home Buyers Inspection Service and Queensland Building Inspection Service, QBIS.
These unsuitable retaining walls have moved and would need a large amount of money to remove and replace. Due to limited access with machinery. Therefore replacing them would be labour intensive and very costly.
Large gaps caused by the soil pushing against the loose tubes of concrete. Concrete tubes are not designed for retaining large volumes of soil, certainly not soil levels over 1 metre in height.
Loose block walls are suitable for retaining small volumes of soil only, less than 1 metre in height. They are not suitable for retaining large volumes of soil.
Another example of retaining wall movement with loose concrete tubes used in construction.
Retaining walls that are over 1 metre in height must be:
- Council approved.
- Engineer designed.
- The soil must be tested.
- Concrete filled and reinforced (most block walls).
- Have drains fitted to the lower section (to help relieve water pressure build up).
Although retaining walls that are less than 1 metre in height don’t require the above they must be constructed well enough to avoid movement from occurring.
Retaining walls can be built in different forms:
- Rock (small and large).
- Timber sleepers.
- Concrete sleepers.
- Blocks (loose or reinforced).
- Formed concrete (crib-lock).
Their life expectancy is dependent on:
- Materials used in their construction.
- Differing weather conditions.
- Proper drainage.
- Type of soil.
- Method of construction.
Dangers of retaining wall movement and common concerns:
- Effect movement of the retaining wall may have on a house, if up against them.
- Movement of retaining walls should have no direct effect on a building unless the building has been incorrectly built or is reliant upon the retaining wall for support.
- on a building if they have bee If the wall has been constructed below the lower side of the house on a property with a significant slope. In the majority of cases, the answer would be, no affect.
In the majority of cases a house is built and supported by its own footings that are independent of a retaining wall.
For independent Building Inspections Brisbane in all suburbs, Qld Home Buyers Inspection Service. qbis.com.au