3/8" Crushed Stone: the Top Course Decision

By the time most people reach this page, the decision is already narrowed to three materials and one question: which one goes on top. The base is sorted, the depth is sorted, and what is left is the layer people will see, walk on and complain about. 3/8" Crushed Stone is the middle answer, and on ground that spends four months frozen and two months draining, the middle answer is usually the right one.

The spec is short: approximately 3/8 inch, angular crushed stone. Angular is the operative word. The broken faces are why it compacts into a surface instead of behaving like loose gravel.

The real choice is between three materials, not twenty

• Screenings at 1/4 inch minus is finer, binds harder and makes a very smooth surface, but it tracks indoors and erodes where water runs across it.
• This grade sits between screenings and conventional crushed stone. It packs tight, it is comfortable underfoot, and the pieces are large enough to stay outside rather than travel in on boots.
• Walkway Gravel is the same nominal size in a graded mix, sold specifically for paths and garden routes.

If the surface has to look finished and stay level, the choice is between the first two. If it is a garden route through beds, the third is the one shaped for it.

Pick it for these, pass on it for those

The pass column is not a warning about quality. It is a reminder that a 3/8 inch chip has neither the mass to resist water nor the depth to carry weight on its own.

On a drive top, a patio and in a pipe trench

• On a drive, it goes over a compacted base and settles into the openings in the coarser course below, which is what gives a gravel drive an even surface instead of a stony one.
• On a patio or a walk, it either makes the finished surface or it fills between set stones, depending on how formal the finish needs to be.
• Around pipe and conduit, the small consistent pieces work in under the haunches and around fittings, giving even support along a run rather than bearing on a few high points.
• In a bed or a tree ring, it holds a clean edge and does not float away in a downpour the way bark does.

The layer under it is the one doing the work

Frost sits 48 to 72 inches deep under pavement by late winter in this state, and no surfacing material changes that. What changes it is the build underneath.

• On the tight clays through the Fox Valley, around Green Bay and along the Lake Superior shore, expect a compacted base of 3/4" Traffic Bond, and on genuinely soft ground a coarse layer of Breaker Run below that again.
• On Central Sands outwash the build can be thinner, though a separation layer keeps sand from working up into the chips.
• On Driftless silt loam, get the cross fall right before anything else. Water running along a path rather than across it will find the fines and take them.
• Everywhere, strip sod and topsoil first. Organic material under a finish course keeps settling long after you have finished admiring it.

Measuring a flagstone walk, bed surrounds and a play-area apron

Square feet times depth in inches divided by 12, then divided by 27 for cubic yards. The site publishes roughly 2,800 lb per cubic yard for the #89, #8 and 3/8 inch chip family, or 1.40 tons per yard, so yards times 1.4 gives tons. Three hypothetical jobs:

• Flagstone walkway, 3.5 ft by 50 ft, filled and dressed at 2 inches: 175 sq ft x 0.167 = 29.2 cubic feet. 29.2 divided by 27 = 1.1 cubic yards, or about 1.5 tons.
• Gravel surround to six raised vegetable beds, 380 sq ft of gravel once the bed footprints are subtracted, at 2.5 inches: 380 sq ft x 0.208 = 79.2 cubic feet. 79.2 divided by 27 = 2.9 cubic yards, or about 4.1 tons.
• Apron 5 ft wide around a 20 ft by 24 ft play area at 2 inches: outer 30 ft x 34 ft = 1,020 sq ft, less 480 sq ft inside, leaves 540 sq ft. 540 x 0.167 = 90 cubic feet. 90 divided by 27 = 3.3 cubic yards, or about 4.7 tons.

The play surface inside that apron is a separate decision, and rounded Pea Gravel is the kinder material under a swing than an angular chip. Run any of these through the Stone Calculator to confirm them.

Choose a tonnage and a delivery date on this page, or send the measurements over through the contact page if you would rather talk them through. Delivery is arranged at checkout from your ZIP code, and the truck needs a clear, firm spot to tip and turn.