Drain Rock for Ohio Footing Lines, Wall Backfill and Dry Wells

A block wall that weeps every March and a back lawn that ponds after every storm sound like the same complaint, and they are not. One is water arriving at a wall with nowhere to go, which drain rock and a pipe can carry away. The other is a low spot in slow glacial clay with no fall out of it, and no amount of washed stone will change that. On the flat lake plain in the northwest, where the ground sits so level that snowmelt waits for ditches and field tile to take it, this is the difference between a fix and an expensive hole.

Choose it when the water has an exit, and skip it when the grade is the problem

Take it when there is somewhere for the water to go and something has to hold an open path to get it there: a footing line running to daylight, a trench tied into a tile, a column behind a wall with a weep at the bottom, a pit under a downspout on ground that drains once the water is below the topsoil.

Skip it in three situations. Skip it in a hollow with no outlet, where the correct materials are fill dirt to raise the grade and top soil to finish it. Skip it as a shed or garage pad base: a pad wants a compactable structural layer, which is 304 limestone, and washed stone under a shed floor will stay loose and shift for as long as the building stands. And skip it where the layer will be walked on daily, because loose 3/4 to 1-1/2 inch stone is an ankle hazard.

Rounded or angular changes how the trench holds up

Both forms are washed to the same standard, so both drain. What differs is what happens under pressure. Angular pieces interlock and keep their voids open when backfill, a slab or a wall is bearing on them, which makes angular the sensible choice beside a footing or behind a retaining wall. Rounded stone settles tighter under the same load and gives up some of that open structure, but it looks like water-worn stone rather than broken rock, which earns it a place in a visible drainage feature.

Picture it as a simple rule: buried and loaded, take angular; seen and unloaded, rounded is fine.

Footing lines, leach fields, wall backfill and a downspout pit

Along a footing, the stone forms the collector that takes water at the base of the wall and moves it to the outlet. Behind a retaining wall, it becomes a vertical column that stops pressure building in wet clay backfill, which is what pushes garden walls over in a wet Ohio spring. In a septic drain field it is the porous layer the system is built around, and the sizing and depth there come from the system design rather than from a product page.

A downspout splash area is the smallest version and the one most people start with. A pit of washed stone under the outfall takes the burst of roof water and lets it soak away instead of cutting a channel through the lawn. It only works where the ground below will accept water; on heavy clay the same pit needs a pipe out of it to somewhere lower.

Washed stone stops at the top of the trench, so plan the cover

Washed stone has no fines, so there is nothing to wedge between the pieces and nothing to pack. It will not form a surface, a base or a bearing layer, whatever is rolled over it. Its job finishes at the top of the trench.

That means planning the cover before the stone goes in. In a lawn, fold fabric over the stone, then soil and seed or sod. Under a walk or a drive, put the structural layers above it and keep them separate with fabric so the base does not sink into the drainage layer. Where the stone is left exposed as a feature, expect leaf litter to work into the top few inches over a few seasons; a blower and an occasional top-up keeps it open.

Backfilling 32 feet of wall, counted in cubic yards

Take a hypothetical block retaining wall, 32 feet long and 4 feet tall, with a 12 inch column of drain rock behind it.

• Face area: 32 x 4 = 128 square feet
• Column thickness: 12 inches = 1 foot
• Volume: 128 x 1 = 128 cubic feet
• Cubic yards: 128 / 27 = 4.7 cubic yards
• Tons, using the site's closest listed figure of about 2,800 lb per cubic yard, or 1.40 tons per yard, as an approximation for this grade: 4.7 x 1.40 = 6.6 tons

Seven tons is the order. That figure is approximate because a larger washed stone sits a little more open than the crushed grade the published weight belongs to, so treat the tonnage as a guide and the cubic yards as the firm number. The river rock calculator is the tool this site points at drain rock, and it will run the conversion on your own measurements.

Once you have a figure, set the quantity and the delivery date above. Delivery is arranged at checkout from your ZIP code, and the truck needs a clear route and a spot where the bed can be raised. A pile of washed stone rolls, so pick flat ground near the open work rather than the top of a slope.