Hardscape Base Materials Explained: What Goes Under Pavers, Artificial Turf, and Retaining Walls?
Every hardscape project — pavers, artificial turf, retaining walls — lives or dies by what's underneath it. The surface material gets all the attention, but it's the base that determines whether a patio stays level for twenty years or starts shifting within two. Skimping on base prep is one of the most common (and most expensive) mistakes made on both DIY and professional installs.
Here's what actually needs to go underneath each type of hardscape project, and why it matters.
Why Base Preparation Is the Foundation of a Hardscape Project
Hardscape surfaces don't fail because the pavers or turf themselves are defective — they fail because the ground beneath them wasn't prepared to handle weight, water, and time. A proper base does three jobs at once: it distributes weight evenly, it manages water so it doesn't pool or erode the structure from below, and it prevents the shifting and settling that leads to cracked pavers, sunken turf, or a leaning retaining wall.
Cutting corners here doesn't save money — it just delays the cost and makes the eventual fix more expensive.
What Goes Under Pavers
Paver installations depend on a layered base system, and each layer serves a specific purpose:
- Class 2 base (compacted aggregate): This forms the structural foundation, typically 4-6 inches deep depending on the application, and needs to be compacted in lifts rather than all at once to achieve proper density.
- Bedding sand layer: A thin, screeded layer on top of the compacted base gives pavers a level, workable surface to set into.
- Edge restraints: Often overlooked, these keep the entire system from spreading outward under load over time.
Without adequate compaction at the base layer, pavers will settle unevenly, creating the rocking or sinking pavers that are one of the most common paver complaints.
What Goes Under Artificial Turf
Turf might look like a simple surface install, but the base underneath does the real work of drainage and longevity:
- Class 2 base or decomposed granite: Provides a stable, well-draining foundation that won't shift or create low spots under the turf.
- Proper compaction: This layer needs to be compacted and graded correctly before turf goes down, since any unevenness in the base telegraphs directly through to the surface.
- A weed barrier layer: Placed between the base and turf backing to prevent growth from pushing up through the surface over time.
Poor base prep under turf tends to show up as puddling after rain or uneven, spongy areas that develop within the first year or two.
What Goes Under Retaining Walls
Retaining walls carry real structural loads, and their base requirements are the most demanding of the three:
- Compacted Class 2 base: Forms the footing the wall sits on, and needs to be compacted thoroughly since this layer bears the weight of the entire wall system above it.
- Drainage rock behind the wall: Placed behind the wall face to allow water to move down and away rather than building up hydrostatic pressure against the structure.
- Filter fabric: Separates the drainage rock from surrounding soil, preventing fine particles from migrating into the rock and clogging the drainage path over time.
A retaining wall without proper drainage behind it is one of the most common causes of wall failure — the pressure from trapped water eventually pushes the structure out of alignment, regardless of how well the wall itself was built.
Compaction: The Step That's Easy to Rush
Across all three project types, compaction is the step most likely to get shortchanged — especially on DIY projects. Aggregate base material needs to be compacted in layers (called lifts), typically no more than 2-4 inches at a time, with each lift compacted before the next is added. Skipping this and compacting one thick layer all at once leaves the base looser than it looks, and that hidden settling shows up months later as an uneven surface.
Getting the Right Base Material for Your Project
The right base material and depth depends on the specific project, soil conditions, and expected load — a driveway paver base needs different specs than a garden path, and a tall retaining wall needs more robust drainage than a short one. At North County Supply, we supply Class 2 base, drainage rock, decomposed granite, and filter fabric to contractors, landscape professionals, and DIY homeowners across San Diego, Riverside, and Orange Counties, with delivery available for projects of any size. If you're planning a hardscape project, reach out and our team can help you figure out exactly what materials and quantities you'll need to build it right the first time.
