The support begins below the aggregate
Soil strength, moisture and preparation affect how a pavement system behaves. A neat final surface does not document the condition of the underlying ground. Ask the contractor how the subgrade will be evaluated and what happens if excavation reveals unsuitable material. Distinguish that investigation from simply specifying the aggregate base above it.
Preparation follows the intended system
A conventional pavement and an infiltration-oriented permeable pavement may have different preparation objectives. Excessive assumptions about compaction can conflict with infiltration goals, while inadequate support can lead to movement. Follow the project-specific requirements rather than one routine instruction for every soil and paving system. Keep unexpected ground conditions documented before layers are covered.
A practical homeowner example
A settled driveway area is lifted for repair. The contractor checks whether the concern is limited to bedding or extends into base and soil, instead of assuming every depression can be corrected at the surface.
This is an illustrative planning scenario, not a report of a particular West Coast Screening project.
Questions to bring to an estimate
- Identify the affected area, intended traffic and existing pavement system.
- Keep unit, joint, bedding, base and soil questions separate.
- Ask how drainage and perimeter restraint are included in the scope.
Frequently asked question
Is subgrade another name for road base?
No. Subgrade is the supporting soil. Road base usually refers to an aggregate layer placed above that soil within the pavement system.
Related glossary terms
For the broader vocabulary, return to the pool cage and screen-enclosure glossary.
Authority sources and further reading
- CMHA — Glossary of Terms for Segmental Concrete Pavement
- CMHA — Application Guide for Interlocking Concrete Pavements
Use these sources within their scope. Manufacturer information applies to the identified product; research and general guidance do not establish a rating or an approved repair for an individual project.