- Benchmark
- A fixed reference point from which all heights are measured. It might be a survey mark, a kerb nail or a peg set by the surveyor. It must not be disturbed during works, so protect it and record its value.
- RL
- Reduced level, the height of a point relative to the benchmark. Plans show RLs for floors, driveways and drainage, often tied to Australian Height Datum. Comparing RLs on site with the design shows how much cut or fill is needed.
- Cut and fill
- Removing ground from high spots and placing it in low spots. Balancing the two keeps material on site and reduces truck movements. Fill needs suitable soil and compaction, and excess cut may need classification before it can leave the property.
- Fall
- The slope given to a surface so water runs in the intended direction. It is often shown as a percentage. Paving, lawns and pads should fall away from buildings, towards a drain or approved discharge point, never towards a neighbour.
- Subgrade
- The trimmed ground surface before base, slab or paving goes on. It is set below finished level by the thickness of everything above it. An accurate subgrade means even layers on top, so material is not wasted in low spots.
- Tolerance
- The allowed variation above or below the design level. Tighter tolerances apply under slabs and pavers than under lawn. The builder, engineer or product supplier sets the figure, so ask for it in writing before trimming starts and check against it.