A gravel driveway in North Carolina is built in layers, and each layer uses a different stone. Coarse stone such as #4 goes on soft ground, ABC or crusher run makes the compacted base, and a finer packing stone or a clean stone such as #57 goes on top depending on the grade and the drainage.
How stone is named in North Carolina
Quarries and stone yards sell crushed stone by a size number. NCDOT's specifications list standard sizes such as #4, #5, #57, #67 and #78M, plus ABC. The lower the number, the bigger the stone. A #4 stone is much coarser than a #57.
Most sizes are clean stone, washed or screened so the fine material is gone. Clean stone drains well, but the pieces do not lock together on their own.
ABC is different. It stands for aggregate base course, and it is graded from coarse pieces down to fine dust. That mix is what lets it compact into a hard layer. Many yards also sell crusher run, which is a similar mix. Ask the yard whether their crusher run meets the ABC specification, because it is not always the same product.
ABC and crusher run: the base
For most driveways in the state, the main structural layer is ABC or crusher run. It is spread in lifts and compacted, and the fines fill the gaps between the larger pieces. The result is a firm, tight layer that carries trucks without rutting.
Because it packs tight, ABC sheds a lot of water off its surface. That is a strength on a crowned drive and a weakness on a flat one. Water has to be given a way off the edges.
On a steep drive, ABC is often the right top surface too. The fines bind the stone so it does not roll under the tires as you climb. See our gravel driveways page for how we build on grade.
#57 stone: clean, drains well, moves under tires
#57 is one of the most common clean stones sold in North Carolina. With no fines, water drains straight through it. That makes it a good choice for drainage work: around pipes, behind walls and in French drains.
As a driveway surface, it is a trade-off. It looks clean and does not get muddy. But the pieces roll under tires, especially on a slope or where cars turn. On a steep mountain drive, a loose clean stone surface can push into the ditches and leave the base bare.
On flatter ground, a thin top layer of #57 over a compacted base can work well. On a climb, most drives hold better with a packing stone on top.
#4 and larger stone for soft ground
Some ground is too soft to build on directly. Wet cove bottoms, spring-fed spots and fill that was never compacted all fall into this group. Fine base stone laid there just pushes into the mud.
The fix is a layer of coarse stone first. #4 is a common choice, and some yards also carry a larger #3 stone. The big pieces bridge the soft spot and spread the load. On top of that goes the compacted base. Fabric under the coarse stone often helps too. Our guide on what to put down before a gravel driveway covers that step.
Which size you need depends on how soft the ground is. That is a call made on site, not from a chart.
Surface stone: what you drive on
The top layer is the part you see. It also takes the wear. You have three broad choices.
A packing stone such as ABC or crusher run gives a firm surface that holds on a slope. Smaller clean stones such as #67, #78M or #89 give a neater look and a smoother ride on gentle grades, but they move more. Stone dust or screenings is fine material that packs hard. It is sometimes blended in to help a surface bind.
Rounded stone such as pea gravel is not made for driveways on grade. It rolls like marbles. Riprap is the other end of the scale, used to armor ditches and culvert outlets rather than to drive on.
Ask the yard, then ask the ground
Names vary by quarry, and the same name can mean slightly different stone at two yards. When you price stone, ask for the size number and whether it is washed. Ask whether a base stone meets NCDOT's ABC spec.
The ground and the grade decide the rest. A flat drive on firm ridge soil and a long climb through a wet cove need different stone in different places. When we quote a drive, the stone list comes from walking it. Read our gravel driveway cost guide for how stone fits into the price, or call (828) 540-6856.
The Short Version
- Crushed stone is sold by size number. The lower the number, the bigger the stone.
- ABC, aggregate base course, is a graded mix that compacts into the main base layer. Crusher run is similar; ask whether it meets the ABC spec.
- #57 is clean stone that drains well but rolls under tires on a slope.
- Coarse stone such as #4 bridges soft ground before the base goes on.
- On steep drives, a packing stone on top usually holds better than loose clean stone.
Quick Answers
Is crusher run the same as ABC stone in NC?
They are similar mixes of coarse stone and fines that compact hard. ABC is the NCDOT specification name. Some yards' crusher run meets it and some does not, so ask the yard.
Should I use #57 stone or crusher run on my driveway?
Crusher run or ABC for the base and, on a slope, for the surface too, because the fines bind it. #57 drains well and stays clean, but it rolls under tires and moves on a climb. On flat ground it can make a good top layer over a compacted base.
What gravel goes on a muddy spot in a driveway?
A layer of coarse stone such as #4, often over geotextile fabric, then a compacted base on top. Adding fine stone straight onto mud just pushes it in. Find out why the spot is wet too, because water is usually the cause.
Why does the gravel on my steep driveway keep washing into the ditch?
Loose clean stone rolls under tires and moves with runoff on a slope. A packing stone with fines binds better, and a crown plus a working ditch keeps water off the surface. See our driveway repair page or call (828) 540-6856.
See our gravel driveway installation service or call (828) 540-6856.