Installing Concrete Pavers Over an Existing Gravel Driveway

A homeowner wants to place 20×20 in pavers on a 7-inch grid over an existing crushed-rock driveway, using the rock as joint filler.

Verify the Base First

Dig test holes: the gravel must be uniform, well-compacted, and ≥6 in thick. If thin or soft, it will settle unevenly.

Leveling Course: Use Decomposed Granite

Sand is for tight-jointed pavers. With 7-in gaps, a 1–2 in layer of decomposed granite (DG / granite fines / M10) over the gravel provides a smooth, compactible bedding layer.

1. Spread DG, screed level.
2. Compact with hand tamper (12×12 in plywood on 2×4).
3. Set pavers, tap to level.

Critical: Uniform Subgrade Across Entire Patio

If part of the patio is on old driveway and part on new fill, differential settlement will warp the surface. Excavate the entire area to a common subgrade and rebuild the base uniformly.

Joint Filler

The existing coarse rock works as joint filler. For stability, consider a finer angular chip (¼–⅜ in) that locks better.