Pea Stone: What It Fixes and What It Cannot

The order usually starts with a bare strip. A side yard the dog has worn out, a track to the shed that grass gave up on, a patch beside the camp steps that turns to mud every time it rains and never quite dries.

Pea stone covers that ground and keeps a boot out of the mud. It is about 3/8 inch, naturally rounded rather than crushed, in tans, creams, grays, browns and the occasional red.

Rounded is the word doing the work here. It explains everything this material is good at and everything it is not.

Pea stone against the three materials people weigh it with

The crushed version of the same size is the one to think hardest about. If the surface has any grade to it, angular pieces will hold where round ones roll.

Where rounded stone is the right answer

Its virtues are underfoot and in the eye.

Bare feet, first. Nothing sharp in it, which is why it ends up around fire pits, at outdoor showers and in play areas at camps.

Drainage second. Water goes straight through a 3/8 rounded layer rather than sitting on it, which suits a strip at the drip line, the base of an outdoor stair, or a bed where turf would not take.

The color is the third reason, and the honest one. The earth tones are in the stone rather than on it, so they do not fade the way a dyed bark does, and a bed of it reads finished from the first day.

Two places it will not stay: a culvert outlet and under a shed

Moving water takes it. A culvert outlet or a ditch line with any real flow will move 3/8 rounded stone in the first heavy storm, and spring runoff here arrives with weeks of snowmelt behind it. That work wants RipRap or a coarse angular stone.

Load crushes the other case. A shed or garage pad has to carry weight and resist rutting, which needs a compacted base of crushed gravel. Rounded stone will never compact. It shifts under a foot, and it shifts under a trailer wheel far worse.

A third one, less obvious: nobody should specify it for a drive. Loose rounded stone under tires piles at the edges within a season and rolls under a boot every time you step out of the vehicle.

Depth, edging, and what goes under 3/8 inch stone

Two inches is the working depth over a prepared surface, three where it is taking regular foot traffic. Deeper is not better. Anything past three inches and a boot sinks in rather than walking across the top.

Under it goes fabric, then a compacted base if the ground is soft or the route is used daily. Straight onto bare soil, the stone works down into it and the weeds come up through it inside two seasons.

Edging is not optional with this material. Round stone migrates, that is its nature, and an unedged bed will be in the lawn by the second spring. Steel, timber, set stone or a cut trench edge, but something, pinned deeper than the layer itself.

Where frost heaves an edging every winter, pin longer and accept resetting it. Nothing edged here stays perfectly straight through four feet of frost.

Cubic yards for a 14 by 18 stone bed, a 36 foot ditch line and a shed pad

Three hypothetical jobs. Pea stone runs about 2,800 lb per cubic yard on this site's published figures, near enough to 1.40 tons per yard.

Dry rock garden bed, 14 ft by 18 ft, 2 inches deep

• 14 x 18 = 252 sq ft
• 252 x 2 / 12 = 42 cu ft
• 42 / 27 = 1.56 cu yd
• 1.56 x 1.40 = 2.2 tons

Ditch line, 36 ft by 4 ft, 4 inches deep

• 36 x 4 = 144 sq ft
• 144 x 4 / 12 = 48 cu ft
• 48 / 27 = 1.78 cu yd
• 1.78 x 1.40 = 2.5 tons

Correct arithmetic, wrong material. That volume should go in armor stone, not in pea stone, unless the ditch carries nothing more than roof runoff.

Shed pad, 12 ft by 16 ft, 6 inch compacted base

• 12 x 16 = 192 sq ft
• 192 x 6 / 12 = 96 cu ft
• 96 / 27 = 3.56 cu yd

At the 3,000 lb per cubic yard this site publishes for road base, that is 5.3 tons of crushed gravel. Pea stone can go on top as a finish once the pad carries the load.

The pea gravel calculator takes other shapes, including circles for a fire pit surround.

Choosing a drop spot for stone that rolls

Pick the quantity and a delivery date on this page. Delivery is arranged at checkout by ZIP code, and the truck needs firm ground, room to back and clear height to raise the body.

Then think about where the pile goes, harder than you would for any other material here. Rounded stone spreads out when it lands and keeps rolling afterwards, so a pile tipped on a slope will be a wide, thin, annoying layer by the time you get to it.

Flat ground, a tarp underneath, and a boarded lip along the downhill side if there is any grade at all. Raking loose 3/8 stone out of grass is the slowest work on any camp project.

New Hampshire Rock Supply lists the edging stone and the base materials on the products page if one trip can cover the whole job.