Roadbase Under Pavers

The Foundation Your Pavers Need

A proper paving installation requires two distinct base layers: the compacted roadbase sub-base that provides structural support, and the sand bedding layer that allows fine levelling and paver placement. This page calculates the roadbase sub-base, which is the critical structural component that prevents your pavers from sinking, shifting, or becoming uneven over time. For a courtyard or patio of 5 metres by 5 metres, you'll need approximately 2.5 cubic metres of DGB20 roadbase at 100mm depth, weighing around 4.5 tonnes.

The 100mm sub-base depth is suitable for pedestrian areas like patios, courtyards, and footpaths. For paved driveways or areas that will see vehicle traffic, increase to 150mm or more. The sub-base is what carries the load, so it needs to be adequate for the heaviest use the area will receive.

Complete Paving Base Structure

A typical paving cross-section includes several layers. Starting from the bottom: compacted subsoil, compacted roadbase (this calculation), and washed sand bedding of 30mm. The pavers then sit on the sand layer and are locked in place with joint sand. Each layer plays a specific role, with the roadbase providing the main structural support and load distribution. Skipping or undersizing any layer compromises the entire system.

Compaction Before Sand

The roadbase must be thoroughly compacted before placing the sand bedding layer. Use a plate compactor for most residential projects, making multiple passes until no further compaction occurs. The surface should be firm enough that walking on it leaves no visible footprints. Check levels carefully at this stage, as any unevenness in the roadbase will transfer through to the finished paved surface. It's much easier to correct levels in the roadbase than to fix a completed paving job.

Calculate the sand bedding layer with our sand under pavers calculator. Use our main roadbase calculator for different paved areas.