Choosing the right gravel for the job

The clean vs dense-graded fork

Every choice starts here. Clean stone is washed and single-sized: it drains freely, never turns to mud, and stays loose forever. Dense-graded stone contains fines down to dust: it compacts into a firm surface and sheds water rather than passing it.

Use clean stone anywhere water needs to move through — drains, dry wells, behind retaining walls, under slabs where a capillary break is wanted. Use dense-graded anywhere a load needs support — driveway top courses, paver and slab bases, shed pads.

The six workhorses

Pea gravel (3/8 in, rounded) is comfortable underfoot and attractive, but rounded stone will not lock together — it migrates, so it needs edging and is a poor driveway surface.

#57 stone (3/4 in, clean, angular) is the universal drainage and sub-base aggregate. It is also the standard fill for French drains and behind walls.

Crusher run / DGA (3/4 in down to dust) is the compactable base for driveways, patios and pads. It is the default answer whenever something has to be driven or built on.

Stone dust / screenings is the fines fraction: a smooth setting bed for flagstone in dry climates, but it holds water and is not a good bedding choice where it freezes.

River rock (rounded, 1-3 in) is decorative and drainage-friendly, used in dry creek beds and beds where a natural look matters.

Decomposed granite compacts into a firm, permeable natural-looking path surface, and is the standard for garden paths in the West — though it tracks indoors and erodes on slopes above about 5%.

Common mismatches

Pea gravel on a driveway: rounded stone cannot interlock, so it rolls under tyres and ends up in the road. Crusher run is the right product.

Crusher run in a French drain: the fines clog the void space and the drain stops working within a season. #57 clean stone, wrapped in fabric, is the right product.

Stone dust under pavers in a freeze-thaw climate: it holds water, freezes and heaves. Concrete sand or #8 chip is the right product.

Colour, angularity and cost

Colour comes from the source rock — limestone is grey to buff, granite pinker and harder, trap rock dark grey. Local rock is always cheaper because aggregate cost is dominated by haul distance, not by the stone itself.

Angular stone locks; rounded stone rolls. Where the aggregate must stay in place under load, choose crushed and angular even when the rounded product looks better.