A building application is not required for a retaining wall according to Schedule 1 of the Building Regulations 2006 if:
- There is no surcharge loading over the zone of influence for the wall (within 1.5m of the wall) and
- The total height of the wall and of the fill or cut retained by the wall is no more than 1 metre above the wall’s natural ground surface and
- The wall is no closer than 1.5m to a building or another retaining wall.
If the proposed structure cannot comply with any of the above, then a building application is required.
A building application is not required for a retaining wall with a fence on top if the combined fence/wall structure is:
- In any part of property within 6m from the corner facing intersection
- In any part of property more than 6m from the corner facing intersection
- Along the truncated curve which is 6m from corner
- Anywhere within the property boundary except that area within 6m of the corner facing the intersection
- Above the natural ground does not exceed 1 metre in height
- The whole structure does not exceed 2m above natural ground and
- The retaining wall component is less than 1m high.
If the structure exceeds the permitted height then a preliminary approval for relaxation of the Queensland Development Code needs to be obtained and a permit is required before starting to build.
A development application may be required if filling / excavation work triggers the requirement for planning approval. If required, this approval must be obtained before a building permit can be issued.
Retailing wall definition
The Building Act 1975 section 75 requires that if soil conditions, ground levels, excavation or filling make it necessary to protect land, buildings or structures in the neighbourhood then:
a) Retaining walls, or other suitable methods must be used, to prevent soil movement and
b) Drainage of the land, buildings or structure must be provided.
Drainage is an integral part of retaining walls. The Building Act 1975 section 76 requires that where drainage is part of the approval of the work, it must be carried out in a way that protects land, buildings and structures in the neighbourhood. If the work is self-assessable, the work must comply with manufacturer specifications or refer to NMP1.7 of the Queensland Development Code for recommended acceptable solutions/performance criteria.
Obligations of the builder
If the retaining wall does not trigger the requirement for either building or development approval this does not negate the responsibility of the owner.
Excavation / filling on a site
Schedule 1 of the Building Regulations 2006 concerns certain excavation of / filling on a site and states when this work is considered self-assessable.
Refer to Mandatory Parts 1.1, 1.2 and MP 1.4 of the Queensland Development Code. The whole of the structure, including sub-drainage, spoon drainage on the top/at the base of the wall, footings, etc. must be wholly within the boundary of a property. The owner of the property on which the wall is located is responsible for the maintenance of the structure.