The sub-base supports the surface and helps distribute loading into the ground. On some paving systems, it also plays a drainage or storage role. Its required material and thickness depend on the site and design, so a universal depth taken from a photograph is not a reliable specification.
Ground conditions change the requirement
Firm, consistent ground and an area of old mixed fill create different situations. Excavation can reveal weak spots or previous trenches that were not obvious beforehand. The installer should explain how such findings will be assessed and addressed.
The intended vehicles matter too. A pedestrian path, ordinary domestic parking and regular heavier loading should not be treated as the same application. Describe actual use before the construction is specified.
Material choice follows the system
Conventional paving and permeable paving can need different aggregate characteristics. A material familiar from one type of driveway may be unsuitable for another. The base must support the surface while preserving any designed water-storage and drainage function.
Compaction and construction sequence matter alongside material quantity. Adding more loose aggregate does not automatically produce better support. The installation method should follow the design and the requirements of the selected system.
Ask for useful records
A clear proposal should describe the layers, intended materials and the approach to unsuitable ground. Photographs taken before the surface is covered can help explain what was installed. Keep them with the product and drainage details.
At handover, a smooth finish cannot prove every hidden layer is correct, just as a construction photograph alone cannot prove performance. The most useful reassurance comes from a suitable specification, competent work and a clear record of what was done.
Question to ask: Why is this build-up appropriate for our ground, vehicles and drainage arrangement? A reasoned site-specific answer is more valuable than an unexplained promise of one standard depth on every job.
Discuss your project
Have a drainage or groundworks question before resurfacing? Ask Smart Paving to assess the site and explain what needs further investigation. Arrange a site visit.
Explore our drainage and groundworks service.
Related reading
- Why wet ground can change a driveway installation programme
- Block paving for heavier family cars: what should change in the specification?
- What base does a resin bound driveway need?
