RETAINING WALL EXCAVATION — GOLD COAST & BRISBANE

Retaining wall excavation is one of those jobs that goes badly wrong if it's done by someone who isn't paying attention to the engineering. Trench width, depth, footing dimensions, batter angles, drainage behind the wall — every one of those matters, and every one of them shows up in your final cost if it's wrong.

We dig retaining wall trenches and batter cuts to engineer's drawings, every time. Sleeper walls (timber, concrete sleepers, steel posts) typically need a 600mm wide × 600mm deep post footing trench. Block walls (besser, masonry) need a wider strip footing — usually 800mm wide × 400–600mm deep. Crib walls and reinforced concrete walls need bigger again.

Batter cuts behind retaining walls are critical and often skipped by less experienced operators. The batter angle (typically 30–45°) lets the wall installer get the full wall built without the bank collapsing into the trench mid-job. We cut the batter to the engineer's angle, install temporary sediment fencing, and protect the cut from rain until the wall goes in.

Drainage behind the wall is mandatory and built into the dig. Ag-line in gravel behind the wall, dropping to a stormwater connection or absorption trench. We dig the drainage trench at the same time as the wall trench, and rough-grade the gravel base ready for the wall installer's drainage detail.

We build retaining walls up to 1 metre ourselves. Taller engineered walls over 1 metre are done in coordination with retaining wall builders we work with regularly across the Gold Coast — Tallai sloping blocks, Mudgeeraba acreage cuts, Currumbin Valley split-level houses, Pimpama and Coomera new estate retaining walls — where we dig, they build, and you get a clean handover.

Cost varies with wall length, height, ground conditions and access. A typical residential 12m × 1.2m sleeper wall trench is $1,200–$2,500 to dig (excludes the wall itself). A 30m × 1.8m block wall footing trench with batter cut and drainage is $4,500–$8,500. Always quoted after a site visit so we can see the access, soil and rock indicators.