3/4" Crushed Stone for Pads and Sub-Bases on Florida Sand

Stand over a fresh pile of 3/4" crushed stone and the first thing you notice is that it holds a steep face instead of slumping the way a load of sand does. That is angular stone doing what it is bought to do. Every piece is a broken fragment at roughly three-quarters of an inch, with flat faces and sharp arrises that catch against their neighbors, and on ground that offers as little bearing as Florida sand that interlock is most of the value.

Sharp fresh faces, no dust on your boots

Pick a handful up and it stays a handful. There is no coating of gray powder on your palm, nothing cakes, and the pieces rattle against each other when you tip them back. The color is the pale gray of crushed limestone, a little darker where the rock is fresh and lighter once it has dried in the sun for a week.

Rake it out and it feels sharp and open rather than dense. Walk on a loose spread and it moves under your boot; run a plate compactor over the same spread and it goes quiet and firm in two or three passes as the faces wedge together. That change is the tell. Rounded gravel never makes that sound because there are no faces to lock.

Because there is no dust in it, water goes straight through rather than sitting on top, which is what makes it usable in a wet-season build when a graded mix with fines in it would be a paste.

Under a spa pad, a shed floor and a turnaround on sand

The jobs it does well share a shape: a layer that has to hold something up and let water pass at the same time.

A hot tub or spa sits on a concentrated static load in a small footprint, and it has to stay dead level for years. A compacted bed of angular stone on prepared subgrade does that, and it drains the splash-out and the summer rain rather than holding a wet ring under the cabinet.

A shed or small outbuilding floor is the same idea over a larger area, with the stone carrying the load and keeping the timber bearers up out of standing water.

A turnaround or parking pad is the heaviest of the three and the one people underestimate. Here the stone works as a sub-base spreading wheel loads across soft sand, with a compacted wearing course over it. Stone alone under tires will migrate sideways at the edges no matter how well it went down.

Why a dog run and a soft bed edge call for something else

A dog run is the request this stone gets most often that it should not take. Three-quarter-inch angular stone has edges, and edges and paws are a poor match over a surface an animal uses daily. Stone Screenings or 3/8" Natural Pea Gravel give a surface that is kinder underfoot and still drains, and both hose down.

The same goes for a bed edge or a border strip where people walk barefoot off a patio. This is a structural stone. It is not a finish.

Setting the depth: compacted inches are the ones that count

Depth figures get quoted loose and installed compacted, and the gap between the two is where orders come up short.

Under a spa, plan on four inches compacted on prepared, firm subgrade, which means spreading close to five loose and rolling it down. Under a shed floor, four inches compacted is a reasonable working figure on sound ground. Under a turnaround taking a vehicle, six inches compacted as the sub-base, with a wearing course above it.

On soft flatwoods sand that stays damp, or on ground that has been filled and not settled, the stone alone will not fix a weak subgrade. Separate the layers with a geotextile so the stone cannot punch down into the sand, or build the grade up properly first and compact it in lifts.

Tons for an 8 by 8 spa pad and a 20 by 24 turnaround

The stone calculator takes length and width in feet, depth in inches, handles rectangles, circles and up to five areas, and adds five percent by default. It works (L x W x D/12) / 27 = cubic yards, then applies density for tons. Florida Rock Supply publishes about 2,800 lb per cubic yard for #57 and 3/4 inch crushed stone, which is 1.40 tons per yard. Three hypothetical pads:

• Spa pad, 8 ft by 8 ft, spread 5 inches loose for 4 compacted. 8 x 8 = 64 sq ft. 64 x (5/12) = 26.7 cubic feet. 26.7 / 27 = 0.99 cubic yards. 0.99 x 1.40 = about 1.4 tons.
• Shed floor, 10 ft by 14 ft at 4 inches. 10 x 14 = 140 sq ft. 140 x (4/12) = 46.7 cubic feet. 46.7 / 27 = 1.73 cubic yards. 1.73 x 1.40 = about 2.4 tons.
• Turnaround sub-base, 20 ft by 24 ft at 6 inches. 20 x 24 = 480 sq ft. 480 x 0.5 = 240 cubic feet. 240 / 27 = 8.89 cubic yards. 8.89 x 1.40 = about 12.4 tons, with a wearing course of roughly 5.9 cubic yards of limerock base at 4 inches on top, which is about 8.9 tons at the published 3,000 lb per yard.

Run your own measurements through the stone calculator, then set a quantity and a date on this page. Delivery is arranged at checkout by ZIP code, and the truck needs a clear route and a firm spot to tip on. Have the excavation cut and the subgrade compacted before the load lands, so the stone goes in once rather than being shifted twice.

3/4" crushed stone next to drain rock and limerock base

Drain rock is the one that gets confused with this most, because the sizes overlap. The difference is purpose: drain rock is washed and can be rounded, and its only job is void space. This stone is angular throughout and expected to be walked on, parked on and built over.