Perth's sandy soils — the defining challenge
The vast majority of Perth is built on sandy, free-draining soil — the Swan Coastal Plain. This affects concrete work in two critical ways. First, sand requires compaction and in many cases lime stabilisation before a concrete slab is poured — the cost of this preparation is sometimes excluded from low quotes and revealed only during the job. Second, sand allows good drainage, which is beneficial for concrete longevity, but tree roots in sandy soil travel significant distances and can undermine slabs over time. Always ask what subgrade preparation is included.
Cracking risk in Perth's climate
Perth's temperature swings — cold mornings and very hot afternoons in summer — create thermal movement in concrete. Control joints (saw cuts) at regular intervals are essential to manage cracking, and they must be placed before the concrete has cured to be effective. A concreter who does not discuss control joint placement before pouring is cutting corners. This is particularly relevant for large areas like driveways and alfresco slabs.
Exposed aggregate — Perth's dominant choice
Exposed aggregate driveways and paths are the dominant choice in Perth residential construction — more so than any other Australian state. The local aggregate varieties (Donnybrook stone, pink quartz, river pebble) vary in availability and price. Local aggregates sourced from the Swan Valley or Gingin are cheaper than imported stone. Ask specifically what aggregate is being used and where it is sourced.
Access and pump requirements
Many Perth homes in established suburbs — Applecross, Como, Mount Pleasant, Floreat — have limited vehicle access to rear areas. Concrete pumping (an additional $500–$1,500) is often required for rear slabs, pathways through narrow gates or elevated alfresco areas. Always check whether pumping is included in the quote or is an additional cost.