Compact the sub-base after each lift; check the moisture level of the sub-base before compacting – a handful of material should hold together when squeezed. If not moist enough, use the water in the onboard water tank (if available) or a garden hose to dampen it, but be careful not to saturate it.

Should I wet soil before compacting?

Moisture content of the soil is critical for proper compaction. Moisture acts as a lubricant within soil, sliding the particles together. Too little moisture means inadequate compaction because the particles can't move past each other to achieve density.

Should you wet sub-base?

You'll want to ensure that the water penetrates the entire depth of the sub-base material from top to bottom, but you'll want to avoid flooding the surface. If the base is too wet, you'll find that your plate compactor sinks too deep into surface.