Earthworks in Harristown

A house pad is the flat, firm area your slab sits on. For a rebuild, the old house comes down, the topsoil is stripped, and the ground is cut and filled to the levels on your builder's plans. Fill is then compacted in layers, which means a roller or plate compactor presses each layer down before the next goes on. Loose fill settles later and cracks slabs, so this step matters more than the digging.

On a sloping block, the high side is cut and the low side filled. The deeper the fill, the more compaction it needs before a slab can sit on it.

An extension needs a smaller pad, often hard against an existing wall. That calls for a compact excavator and careful work so the footings of the house are not disturbed.

Trenching is the narrow digging for stormwater, sewer, water and electrical conduit. Pipes that carry water need a steady fall so they drain properly, and the trench needs a firm, even bed. A trench that is too shallow or uneven is the kind of fault that shows up a year later as a soggy patch or a blocked line.

If a shed pad also needs levelling or a soggy corner needs reshaping, mention it up front. Bringing the machine in once for all of it can cost less than paying for two separate trips, because each trip carries its own cost of getting the machine to your block.

Rock usually costs extra, because it needs a breaker or a heavier machine and takes longer to remove. Many contractors price it at a separate rate per cubic metre, so the written price should say how rock and any old pipe found in the dig are handled before the work starts.

A written contract puts the scope and the price on paper, and the contractor's licence can be looked up on the QBCC register. A careful contractor also locates known services before digging.

Four things drive the cost: how much soil is moved, the size of machine needed, how far the spoil (the excess soil) has to travel, and how much compaction the pad needs. A flat yard with easy access and a short haul costs less to work than a cramped one with a long carry.

Usually yes, because contractors carry a range of machines. A small excavator or a skid steer, a compact machine with a front bucket, can pass through a narrow side gate where a full-size digger cannot. The trade-off is time. Smaller machines move less soil per hour, so a tight yard can mean more days on site.

Spoil is the other access problem. If a truck cannot park close, soil has to be carried or barrowed out, which adds to the price. Overhead lines, fences and trees in the way add to it too.

Townhouses and other attached dwellings need extra care. Shared boundaries leave little room to swing a machine, and neighbours' fences and retaining walls need protecting while the digging goes on.

The pad has to match the builder's levels the first time, because a slab crew cannot pour onto ground that is out of tolerance. A good contractor works from the plans, checks levels as the fill goes in and leaves the surface compacted and trimmed.

Water needs a plan too. If water pools against your house after rain, the ground usually falls the wrong way or a drain is blocked. Reshaping the surface so water runs away from the walls is part of site preparation, and the contractor confirms the fix on site once they have seen how the water moves.