When designing and installing a stone driveway there is surprisingly a multitude of options.
In many cases, more than one kind or size of stone will be used to create a driveway for aesthetic and functional purposes.
Common gravel is popularly used for stone driveways. However, it is also used underneath as a base layer for other stone driveway surfaces for drainage and leveling. Stone surface options include other gravels such as Jersey Shore, Pea, or Blackstar. River rocks, pavers, marble chips, and crushed stone varieties are also used offering different hues and aesthetics.
Ideally, any driveway should be installed with drainage and durability in mind for longevity and low maintenance. Smoother rocks need stabilization to avoid erosion and shifting, whereas irregularly-shaped rocks lock together.
This article will discuss considerations in choosing driveway stone materials and offer a closer look at your options.
Driveway Stone Considerations
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A stone driveway is not simply a truckload of stones dumped onto a surface and spread out with a rake.
Often more than one size and type of stone are used to create a driveway or pathway. This is done to create a surface that efficiently drains and stays put, thus avoiding significant erosion, pooling, and increased maintenance.
Homeowners should also consider the type of and color, durability, maintenance needs, and drainage when designing and installing a driveway.
Stone Size
Stone size can be a complicated matter, so it is important to make sure you understand sizing before placing an order. Keep in mind that numbers used to label stones can vary from region to region.
Stone measurements are approximate and you could have some slightly smaller or slightly larger.
This table gives some general examples:
| Stone Label/Number | Size | Use |
|---|---|---|
| #1 | 2 ½ inches to 4 inches | Large stones used for decorative purposes |
| #3 | ⅜ inch to ½ inch | Used in concrete and asphalt mixtures |
| #10 | ⅛ inch (like coarse sand) | Base for bricks and paving stones; packed in crevices |
| #57 | ¾ inch to 1 inch | Middle layer for pathways and driveways, comprised of #5 (1-inch) and #7 (¾-inch) stone |
| #411 | 1 inch or smaller (dust-like) | Fill or base material for potholes or sealing retaining walls; mixture of #10 and #57 |
Stone Processing
To further complicate stone choices, there are different kinds such as crushed, aggregate, and grades.
This may mean that stone options will contain a mixture of rock materials or sizes, are sifted to remove certain sizes, or pre-washed for size consistency.
Layers
Installed stone driveways have layers to ensure that it stays put. Bigger stones form the base and layers upon it generally decrease in stone size or use fillers to close in the gap.
Layers generally are installed according to the following:
| Layer | Size | Purpose |
|---|---|---|
| Base (bottom layer) | Rocks that are 1 to 2inches | Creates a sturdy foundation and drainage |
| Middle | #57 rock (¾ inch to 1 inch) | Settles into the base layer, while providing drainage |
| Top | Visible rock made of fine or small blended rocks, pavers, concrete, or mixed materials | The top layer settles and compacts into the underlying layers to form a tight bond, thus handling vehicle and foot traffic |
When constructing a stone driveway, make sure you know what function and aesthetics you want. Then, consult with a stone company to find what will work best for your project.
Determine How Much Stone Is Needed
The volume of stone you need for your driveway depends on the type and size of stone you use. The area for the project is measured in cubic feet.
A stone company can help you determine how much stone is needed, but you must have measurements to share with them.
Generally, driveways are minimally 4 inches deep. Measure the length, width, and depth, and input that into a cubic feet calculator.
10 Types Of Driveway Stone
In driveway installations, common gravel is used as a base layer underneath and out of sight for drainage. Including gravel, the following types of driveway stones are used as the top, visible layer.
1. Common Gray Gravel
Gravel is crushed stone mined from quarries or fragments of commercially made or recycled concrete. It appears as light gray, irregular, dusty pieces.
However, the hue may change depending on the crushed stone, such as if using basalt, sandstone, or limestone.
Various Numbers (#)
Gravel is commonly used in driveways for its affordability as well as the base or middle layers for drainage. Typically, it is offered in #3, #4, #57, and #411.
- #3 and #4 are used for base layers, with sand or dirt possibly mixed in to create a firm foundation.
- #57 is used for the middle layer.
- #411 is crushed stone and rock dust and gravel for the top layer.
Due to its irregularity in pieces, it has sharp edges that help it to compact together, but may be painful to walk barefoot on.
Crusher Run
Crusher run gravel is not commonly used for driveways because of its composition of crushed stone and dust.
It compacts tightly to make a smooth surface but prevents good drainage. If this type is used, then the gravel has to be sloped or graded to help water run off.
2. Jersey Shore Gravel
Popularly used in the Northeast, these stones are dredged and pumped up from waters in southern mines located in New Jersey. They come in shades of yellow, gold, white, and brown, resembling the color of sand.
This kind of gravel should be on top of a secure base layer, installed with borders or edging along the driveway to help keep it in place.
3. Pea Gravel
Pea gravel is commonly used as a top layer. It is a type of weathered, round, and smooth river rock. It is more comfortable to walk barefoot on and comes in a variety of colors.
Due to the rounded surfaces of these rocks, they can shift and move easily requiring maintenance in a driveway. It should have a sturdy base of crushed rock or sand when utilized in high-traffic areas.
4. River Rock
Stone labeled as “river rock” is generally larger than pea gravel. It is also smooth and comes in a variety of colors, such as brown, black, or white.
These rocks will significantly shift underneath the weight of vehicles, requiring maintenance.
Generally, these are not used for driveways, so if you choose this method, consult with an expert on how to keep the rocks from moving by using other materials.
These might be installed with concrete to keep them in place, as well as to create a level surface.
5. Blackstar Gravel
Made from Basalt rock, this crushed stone locks well to form a durable surface, with a stabilized base.
It appears gray when dry and black when wet, and comes in a variety of sizes.
6. White Marble Chips
These shimmering white pieces are pleasing to the eye. Marble chips are durable, resisting deterioration and insects.
This more expensive option requires a sturdy base and edging to keep them in place on a driveway. Typically, the driveway will require maintenance and chip replacement as they shift underneath repeated use.
7. Limestone
Crushed limestone is a popular driveway material due to its affordability over asphalt or concrete.
Additionally, limestone is alkaline and therefore an acid neutralizer. This means that when it rains, limestone deposits into groundwater, thus improving the soil’s calcium levels, making plants “happy”.
8. Crushed Stone Varieties
Crushed stone is a durable man-made aggregate from a quarry. The stones are passed through a crushing machine and are used commonly for base layers or cement or mortar mixtures. It comes in sizes from ¾ inch to 4 inches.
Crushed stone can be made of the following types or mixtures of stone:
- Gritstone: coarse, hard sandstone (calcite, clay, or silicate minerals)
- Quartzite: heated and compressed sandstone
- Granite: light-colored igneous rock
- Limestone: Calcium carbonate
- Gabbro: Coarse, black, or dark green igneous oceanic rock
- Basalt: Igneous molten rock in blueish, grayish, or black colors
- Argillite: dark blue with flecks of red and green
- Recycled Stone: byproducts such as iron or steel slag; crushed mixtures of sand, gravel, clay, shale, perlite, slag, and vermiculite
Crushed stone settles and compacts. Therefore, it must be sloped when used on driveway surfaces to allow water to flow off and away.
9. Slate
Slate is layered metamorphic rock that can be processed as slabs in hues of black, gray, red, purple, and blue.
It is sturdy but must be installed correctly with concrete or fillers to prevent movement and excessive flaking.
10. Stone Pavers
Pavers are made from natural stone (such as cobblestone), concrete, or brick. Typically, they are used in conjunction with fill and surface gravel.
Professional installation is generally needed to ensure that the surface is level and drains well.
Conclusion
There are many natural stone and man-made options for driveways.
Generally, the unseen base layer is laid with gravel. Angular and irregularly-shaped stones will stick together well. On the other hand, smoother or larger rocks, such as river rocks, pavers, or cobblestone, need support such as sand or filler rocks for stabilization.
Driveway installations should be done with attention to drainage and durability as well as aesthetic preferences.