A freestanding wall is a standalone wall that is not connected at either end to a building or other structure, and not restrained along the top. Brick front fences are typical examples of freestanding walls.
Over time, a lack of maintenance and other factors can affect the structural integrity of a freestanding wall, creating a safety risk.
You should be aware that the middle sections of long walls connected at their ends to another building or structure can behave as freestanding walls. Unintentionally freestanding walls, such as walls built before a construction project is complete, or walls remaining after demolition, are particularly unsafe.
If you have a concern about the structural safety of a freestanding wall on your property, contact a builder. If you are concerned about someone else’s wall, contact the local council.
Walls that may be unsafe
Older walls can have weak lime mortar, making them more susceptible to damage from high winds or impacts. Walls constructed many years ago may have footings that complied with the standards at the time of construction, but are far less stiff than footings required by current design codes.
Look out for cracks appearing in brickwork – this can weaken the walls considerably. Cracked walls may be caused by differential movement, which is when part of the footing rises or falls in relation to the rest of the footing. This may be caused by changing moisture in the soil or tree roots.
Long walls are susceptible to cracking if they do not have articulation joints (joints that allow movement without causing damage to the structure).
Walls with rotated footings
When the footing of a wall rotates away from its original horizontal position, the wall may lean or crack. As the footing gets lifted on one side, the wall starts to lean out towards the other side. This can be caused by roots of trees pushing up one side of the footing, or changing soil conditions.
Clay soils are particularly prone to changes in moisture content, as they shrink in dry conditions and swell in wet conditions. This causes the footing to rotate higher on the wet side and lower on the dry side, and the wall will lean towards the dry side.
Footing rotation can also occur if the soil on one side of the wall becomes excessively wet, due to poor drainage or plumbing leaks.
Walls being used for a new purpose
If a wall is adapted for a use that was never intended, it may not be strong enough to remain stable. For example, a front garden wall may be used by a later owner as a retaining wall if they decide to create a raised garden bed behind it. This can cause new horizontal pressures on the wall and result in leaning or bowing.
Unintentionally freestanding walls
Walls are sometimes unintentionally freestanding due to construction or demolition, for example:
- one wall of a new garage has been built, but not yet connected to a roof structure
- a masonry façade is retained for heritage significance but the rest of the building is demolished.
When a wall is temporarily freestanding, it must either be propped on both sides or have suitable tension/compression props on one side. Props must be securely connected to the wall and to a suitable footing to provide adequate capacity to resist wind loadings.
Building practitioners should be aware of the precautions and temporary measures they should take when constructing a free-standing wall. Refer to WorkSafe Victoria’s Safety Alert 2013-04 for more information on preventing structural collapse when doing construction, demolition and refurbishment works.