Updated October 2026
Forrestfield is a Swan Coastal Plain suburb below the scarp, developed through the 1970s, and it is flat. That changes the retaining wall conversation completely. We connect you with builders who work the 6058 area.
Common wall situations in Forrestfield
With no slope to hold back, the work here is garden terracing, driveway and crossover edges, pool surrounds, raised beds and levelling a yard that drains the wrong way. These are low walls doing a landscaping job, which means interlocking block, limestone block or timber more often than engineered systems.
That also makes the approval question simpler, though not automatic. A low garden wall well inside your boundary is usually exempt. A wall on the boundary is not.
The City of Kalamunda's strategy records that the urban areas of Wattle Grove, Forrestfield, Maida Vale and High Wycombe are either sewered or have access to a reticulated sewer system, so the on-site effluent constraints that shape jobs higher up generally do not apply here.
Drainage still matters on flat ground
A flat block does not mean water is not a problem. A low wall still needs ag-pipe at its base, free draining gravel rather than the spoil that came out of the hole, geotextile fabric so the drain cannot silt up, and somewhere lawful for the water to go. Walls that fail on the plain usually fail because the drainage was left out to win the price. Our retaining wall drainage page covers what to look for.
What a wall costs in Forrestfield
Published Australian guide figures run from around $200 per metre for timber to $700 or more per metre for stone and engineered block at about a metre high. Garden-height work on a level block is cheaper again, and access here is usually straightforward. Read the retaining wall cost guide before you compare quotes.
Approval, and who to ask in Forrestfield
Approval in WA turns on 500mm of retained ground, not on the height of the wall, and the exemption only applies where the wall is also clear of other building work and is not holding up or affecting the land next door. All three have to be true at once. A wall on or at a boundary is dealt with separately under the Building Act and needs the neighbour's consent or another authority whatever its height. Development approval under the local planning scheme can apply as well, so confirm the position with the City of Kalamunda before anything is quoted.
Who is allowed to build it is a statutory question in WA, and it turns on how the work is classified under the building legislation rather than on a figure you can look up and apply yourself. We are not going to settle that on a web page. What is worth doing is simple: ask the builder what registration or licence they hold, check it with Building and Energy, and ask your permit authority what your particular wall requires before you sign anything. Before any digging, your builder should lodge a free Before You Dig Australia (BYDA) enquiry so underground services are located.
Frequently asked questions
Do I need a retaining wall on a flat block?
Often not a structural one. On flat Forrestfield blocks the usual reasons are levelling a yard, edging a driveway or crossover, building raised garden beds, or creating a level pool surround. All of that is low wall work.
What is the cheapest option for garden terracing?
Treated pine timber is usually cheapest to build, and dry-stacked interlocking block is often the cheapest long-life option at garden height. Reconstituted limestone block costs more and looks like stone.
Is approval needed for a low garden wall in Forrestfield?
A wall retaining no more than 500mm of ground can be exempt, provided it is also not tied to other building work and is not holding up or affecting the land next door. A wall on the boundary needs a permit at any height. Check with the City of Kalamunda.
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We also cover nearby High Wycombe and Maida Vale.