#8 Crushed Stone in Michigan: The Small Clean Stone Water Moves Through

By the second week of the thaw, when meltwater still stands on the flat lake plain clay in the southeast and runs straight down through dune sand on the west side, the gap between the three small stones in this catalogue stops being academic. #8 crushed stone is the one of the three built to let water pass: pieces of about 3/32 inch to 3/8 inch, graded to the #8 designation, clean, with little to no fines in it. The decision worth settling before anything is ordered is simple to state. Do you want water to travel through this layer, or do you want the layer to tighten up and hold still?

Sized 3/32 to 3/8 inch, graded #8, with the fines left out

The pieces are crushed, so the faces are broken and angular rather than water-worn, and they run in a narrow band of sizes rather than from coarse down to dust. That narrow grading is the whole point. With almost no fine material to fill the gaps, the spaces between the stones stay connected, and rain or meltwater drops through the layer instead of collecting on top of it.

Two things follow from that in practice. The pile does not throw dust when it is tipped and does not track gray footprints indoors, which matters on a job near a finished patio. And the layer will never go hard. Run a plate over it and the stones settle into contact with one another, but they stay an open stone, which is exactly why the drainage holds up through years of freezing and thawing.

A use table for the three small stones on this site

Read down your own row rather than across the sizes. Most of the wrong orders on small stone come from matching the number on the ticket instead of matching the job.

Forty-two inches of frost, and what a clean stone can and cannot do about it

Frost reaches 42 inches under the Michigan Residential Code, and in the northern Lower Peninsula and the Upper Peninsula it works on the ground for longer each year. A clean stone helps because water that has drained away is water that cannot freeze under the work and lift it, and that is the argument for putting an open layer under a flagstone walk or a permeable patio rather than setting stone straight onto soil.

What it will not do is make the frost question go away. Anything structural, anything with a footing, is designed against the frost line by a builder or your local building official, not chosen off a product page. Keep the two decisions separate: the stone handles water, the depth of the footing handles frost.

Ground changes the sums as well. On sandy outwash in the west and north, the subsoil already drains, so a clean layer is there to stop the bedding silting up and to give a stable, free-draining bed. On slow-draining clay around Saginaw Bay and across the Thumb, the open layer has to be given somewhere to send its water, or it fills, sits full through the thaw and does nothing useful.

Tons for a 4 by 26 flagstone walk and a drainage blanket under two beds

Take a flagstone walk first, four feet wide and twenty-six feet long, built with an open layer below and a thinner bedding course on top.

• 4 x 26 = 104 square feet
• The open layer at 4 inches: 4 inches is 0.333 feet, so 104 x 0.333 = 34.6 cubic feet, and 34.6 / 27 = 1.28 cubic yards
• The bedding at 1.5 inches: 1.5 inches is 0.125 feet, so 104 x 0.125 = 13 cubic feet, and 13 / 27 = 0.48 cubic yards
• Together that is 1.76 cubic yards

This site publishes a weight of roughly 2,800 lb per cubic yard for #8, #89 and 3/8 inch chips, about 1.40 tons per yard, so 1.76 x 1.40 works out at about 2.5 tons.

Now a drainage blanket under two raised vegetable beds sitting on clay that stands wet in April, each bed four feet by twelve feet, with three inches of stone below the soil.

• 4 x 12 = 48 square feet per bed, so 96 square feet for the pair
• 3 inches is 0.25 feet, so 96 x 0.25 = 24 cubic feet
• 24 / 27 = 0.89 cubic yards, and 0.89 x 1.40 is about 1.2 tons

Both figures are illustrations rather than jobs anyone has built. The beds themselves get filled with garden soil, never with stone, and the paths between them are more comfortable in walkway gravel if anyone uses them daily. The stone calculator will run circles as well as rectangles, take up to five areas in one go and add five percent by default for the stone that vanishes into a soft bottom.

One example that does not belong here at all is a single-car gravel drive. A clean stone with no fines has nothing to bind it, so tires push it into ridges within a season. That work wants compacted 21AA limestone with driveway gravel as the running course.

Picking a date, and where a load of clean stone can be tipped

Clean stone is easy to handle once it is on the ground. It shovels without sticking, wheelbarrows well and can be spread and raked by hand at the sizes above, which is why small hardscape jobs suit it. What it does badly is sit on a slope, so tip it somewhere flat and fetch it from there.

Choose a quantity and a delivery date on this page. Delivery is arranged at checkout from your ZIP code, and the driver needs a clear approach and a firm spot where the truck can put the load down without blocking the trench or the patio you are about to build. If your measurements fall awkwardly between two quantities, run them through the calculator again at the depth you actually intend to lay before you book.