#8 Crushed Stone for Tennessee Wall Drains, Splash Beds and Paver Joints

Orders for this size tend to land in one of two windows. There is the dry stretch in early autumn, once the summer storms have shown you exactly where water runs, and there is the short spell in late winter before the spring rain sets in for good. Both windows matter on a hill lot, because #8 crushed stone earns its keep in trenches and behind walls, and a trench cut into saturated cherty clay will not hold a clean wall long enough to get stone against it.

3/32 to 3/8 inch, with the fines screened out

Size runs about 3/32 inch to 3/8 inch. The grading is #8, which here means clean, with little to no fines in the load, and the material is crushed rather than naturally rounded, so every piece has broken faces.

Those three lines decide everything else. Small angular pieces stack tight against one another but still leave open space between them, and with no dust or grit filling that space, water travels through the layer instead of collecting in it. The same gaps are why a layer of it never firms up into a driving surface. It is a component inside a build, not the thing you look at or park on.

Where #8 crushed stone goes on a hill lot, job by job

Cherty clay, karst runoff and the trench that silts up

Open stone only works while the voids are open, and the ground here is good at closing them. Cherty clay pumps upward into a stone layer under load, and the silt that washes off bare ground in a July downpour arrives from above. Either one turns a drainage course into a wet sponge within a few seasons.

Two habits fix most of it. Wrap the stone in a woven permeable geotextile so the clay stays on its own side, and give the water somewhere to go at the end of the run rather than a place to gather. That second point carries weight in the Central Basin and the Highland Rim, where sinkholes and openings in the limestone already take runoff underground. A drainage detail that discharges toward ground like that wants planning before it wants stone.

A splash bed at four downspouts and a drain course behind a block wall

Two hypothetical examples, worked the way this site's calculator works. Length by width by depth in inches, divided by 12 for cubic feet, divided by 27 for cubic yards. Chips in this family run about 2,800 lb per cubic yard on the figures this site publishes, roughly 1.4 tons to the yard.

Four splash beds, each 6 feet by 3 feet at 4 inches deep. One bed is 18 square feet, so 18 x 4 = 72, divided by 12 = 6 cubic feet. Four of them is 24 cubic feet, divided by 27 = 0.9 cubic yards, about 1.25 tons.

A drain course behind a 30 foot block wall standing 4 feet high, kept 12 inches wide: 30 x 1 x 4 = 120 cubic feet, divided by 27 = 4.4 cubic yards, about 6.2 tons. Put both on one ticket and you are at roughly 7.5 tons. Run your own measurements through the stone calculator before you commit to a quantity.

A farm pond edge is a job for weight, not for chip

The third job people ask about with this material is a pond or shoreline edge, and it is the one to say no to. A 3/8 inch chip has no mass. Wave wash, stock traffic and the rise and fall of the water line move it off the bank within a season, and what is left sinks into the mud.

An exposed edge wants stone heavy enough to stay where it is placed, which means RipRap on anything that scours and large river rock where the edge is meant to be looked at. Keep this size for the bedding under a coping stone or a header course, where it is contained on all sides.

Sequencing the wall order so the chip goes in last

Drainage stone goes in as the wall goes up, not after it, so the order needs to arrive with the block rather than two weeks behind it. Work out the wall course and any splash beds at the same time and put them on one delivery, since the total is usually only a few tons and splitting it gains nothing.

Delivery is arranged at checkout by ZIP code, and the truck needs clear access to a spot where it can tip. The delivery page sets out how that works. Measure, run the arithmetic, then pick a quantity and a date from Tennessee Rock Supply on this page. If the wall sits below a drive and the drop has to happen on the high side, ask about access through contact before you book.