#89 Crushed Stone: the Small Stone That Packs, for Ohio Joints and Bedding

Most patios in this state are being set on ground that fights back. Glacial till across the west and center holds water in a clay loam that gives up moisture slowly, and the plateau counties of the northeast sit on a dense subsoil that perches water part way down. Anything laid on that ground has to be set tight, because loose material and freeze-thaw between them will find every gap by March. That is the situation #89 crushed stone is bought for here: about 3/8 inch down to fines, angular, and carrying enough small material to lock together instead of staying open.

Joints and bedding under flagstone are what this stone is bought for

Sweep it into the gaps between flagstones or pavers and the sharp faces bite against one another while the fines fill in behind them, so the units stop rocking underfoot. Screed it as a bedding course and you get a firm, even layer without the oversized pieces that make a screed board chatter. The same grading gets used in chip-seal work and in small-stone concrete mixes where a mix calls for a fine coarse aggregate.

What a hard winter does to a patio bedded on till clay

Freeze-thaw runs through the whole state, repeatedly, and it works on water rather than on stone. A bedding course that has been placed loose holds water in the gaps between pieces, and every freeze lifts the units above it a fraction. Over one winter that reads as a wobbly flag; over two it reads as a patio with a step in it.

Compacting the bedding before the units go down takes those gaps out. It does not stop the ground below moving, which is why what sits under the bedding matters as much as the bedding does, but it stops the layer you control from being part of the problem. On the flat clay of the northwest, where the ground stays saturated well into spring, that also means waiting. Nobody compacts wet clay successfully in an Ohio April, and work that starts once the ground has drained and firmed usually ends better than work that starts on the first warm weekend.

Screeding the bed and sweeping the joints on a flagstone patio

Bring the area to grade with a compacted base first, then spread #89 as a bedding course of about an inch and screed it flat off two rails. Set the units, then sweep the same stone into the joints with a stiff broom, working it in until the joints stop taking material. A tamper or a plate on a pad brings the surface together and settles the joints; go round the perimeter twice, because edges are where the movement starts.

Keep the material dry in the pile if you can. Fines that have been rained on clump, and a clumped bedding course screeds unevenly no matter how careful the board work is.

Where a dog run, a parking pad and a footing drain each land

A side-yard dog run is a fair fit, with one condition. Laid a couple of inches deep over a compacted base and tamped, it makes a firm surface that does not scatter when a dog corners hard on it. In deep shade on clay it will stay damp and the fines will track indoors, so a run on the north side of the house is usually better in pea gravel or walkway gravel.

A turnaround or parking pad is not its job. Vehicle weight wants a structural base of compacted 304 limestone with 411 stone as the topping, and a bedding grade under a car will rut in one wet autumn.

A French drain along a foundation is the case to get right, because the fines that make this stone good at joints make it useless in a trench. Water needs connected voids, and there are none here once the layer settles. Order #8 crushed stone for a pipe surround, or drain rock for a wider trench, and keep #89 for the surface work.

Set against #8 above it and screenings below it

#8 crushed stone covers a similar size band but has been washed clean, so it drains and never firms up. Same rough size, opposite behavior. Going finer, screenings run from about 1/4 inch down to dust and make a tighter, smoother bed that suits flagstone with narrow joints and firm garden paths, at the cost of holding water longer on clay. #89 sits between the two: enough fines to pack, enough stone to stay gritty underfoot.

Putting a tape on an 8 by 26 side-yard run

Take a hypothetical side-yard run, 8 feet wide and 26 feet long, finished with 2 inches of #89 over a compacted base.

• Area: 8 x 26 = 208 square feet
• Depth: 2 inches = 0.167 feet
• Volume: 208 x 0.167 = 34.7 cubic feet
• Cubic yards: 34.7 / 27 = 1.3 cubic yards
• Tons at about 2,800 lb per cubic yard, or 1.40 tons per yard: 1.3 x 1.40 = 1.8 tons

Two tons is the order, because the last wheelbarrow always disappears into the low corner. For a bedding course the sum runs the same way at a shallower depth, so a 14 by 20 flagstone patio bedded an inch deep comes to 280 square feet, 23.3 cubic feet, 0.9 cubic yards, or about 1.2 tons with the joints allowed for.

Run your own figures through the stone calculator, then pick a quantity and a date above. Delivery is set at checkout from your ZIP code, so have a thought about where a tipping truck can get clear access and where the pile can sit on a hard surface rather than on the lawn you are about to pave next to.