#89 Crushed Stone: The Small Grade That Locks Into a Joint

By the second week of April in the Capital Region, a patio tells you what kind of winter it had. Frost lifted the field, the thaw dropped it again, and the joints between the units have emptied into the lawn in the places where the plow came close. Refilling them is the job #89 Crushed Stone is ordered for more often than anything else on this site's ground: about 3/8 inch down to fines, angular, and carrying just enough dust to grip once it is swept in and vibrated home.

That last point is the whole product. Most small stones on the order form have had their fines washed out. This one keeps them, which makes it useful in a confined space and useless anywhere water has to move.

Order it where a joint or a bedding layer has to stay put

Choose this grade when the stone is going into something that holds it: the gaps between pavers, the thin bed under a flagstone, a chip seal surface, or a concrete mix that wants compactable aggregate. In all of those the material is trapped by something on either side, and the fines give it the grip to stay compacted instead of loosening off each season.

The angular faces matter as much as the fines. Rounded stone of the same size rolls under a broom and lifts out of a joint the first time a leaf blower passes. Crushed faces catch on each other and on the paver edges.

Where the fines make it the wrong load: a drain trench, a sunken corner, a ditch line

Three jobs come up on the same properties and none of them should be given this material.

A French drain along a foundation wants the opposite of this stone. Fines are exactly what closes a drain, and a trench filled with a grade that carries them will hold water against the wall rather than carry it away. That trench wants a washed grade such as 3/4" Crushed Stone, which New York yards sell for exactly that job, or Drain Rock where the bed is wider.

A low spot or a yard regrade is an earthwork job, not a stone job. Stone in a sunken corner gives you a hard, wet patch that mows badly and freezes solid. Bring the level up with Fill Dirt and finish with Top Soil where grass has to grow.

A culvert outlet or a ditch lining on a Southern Tier hillside is hit by water moving with real force, and 3/8 inch stone leaves the site in the first storm. That is armoring work for RipRap.

Joints, flagstone beds and chip seal: the three places #89 crushed stone belongs

In paver joints, sweep it in dry, run a plate compactor with a mat over the surface, then sweep and top again. The second pass matters. Stone drops into the voids under vibration and a joint that looked full before the compactor will read low afterwards.

Under flagstone, it works as a thin bedding layer that can be screeded and tapped level, holding a heavy irregular slab without the slab rocking. On valley clay that stays wet into May, keep the bedding thin and put the drainage in the layer below it, because this grade will not move water on its own.

In a chip seal surface it is the aggregate that gets rolled into the binder, which is a contractor application rather than a weekend one.

It beds and fills, but it never carries the load

The layer that carries weight on a New York drive or pad is a graded base with a full range of sizes in it, compacted in lifts: Item 4 or crusher run. This grade is too small and too uniform to do that work, no matter how tightly it packs in a joint.

Think of it as the top few inches of a build, or the thin layer directly under a unit. Below it there should always be something else: a compacted base on a patio, a firm subgrade under a walk. Get that order wrong and the joints will look excellent on a surface that is quietly settling.

Counting a 14 by 18 patio bed and a 60 foot flagstone walk

Worked examples with invented dimensions.

Patio bedding, 14 by 18 ft, 1 in screeded

• 14 x 18 = 252 sq ft
• 252 x 1 / 12 = 21 cu ft
• 21 / 27 = 0.8 cu yd

Flagstone walk, 60 ft long by 3 ft wide, 1 in bedding

• 60 x 3 = 180 sq ft
• 180 x 1 / 12 = 15 cu ft
• 15 / 27 = 0.6 cu yd

That is about 1.4 cubic yards between them. At this site's published weight for the 3/8 inch chip family, roughly 2,800 lb per cubic yard or about 1.40 tons per yard, 1.4 x 1.40 comes to a shade under 2 tons. Joint fill for both areas comes out of the same load, and it is worth having spare in a covered pile for the top-up pass at the end of the first season.

Use the stone calculator for anything with curves in it, then pick a quantity and a delivery date on the #89 Crushed Stone page. Delivery is set at checkout by ZIP code, so have a firm drop spot chosen that a wheelbarrow can reach.