If you're considering upgrading your gravel driveway to concrete, you'll need to know who thick the concrete should be. Driveway thickness will vary depending on the vehicle type, the slope of the driveway, and the soil conditions beneath the driveway. We've researched thickness options for a concrete driveway so you can plan accordingly for the best result.
A concrete driveway should be four to five inches thick, depending on the type of vehicle being used. Four-inch thickness does the trick if passenger cars are your primary vehicles; but, five-inch thickness is preferred for heavier SUV traffic. Wire mesh and rebar will reinforce your concrete and should also be considered during initial construction. Your aggregate base thickness will depend on the soil type and slope of your driveway. The sandier the soil or steeper the slope of your driveway, the thicker your aggregate base should be.
As you can see, there are many considerations when planning a driveway, so stay with us as we delve into the details. We'll discuss what type of concrete to use, what to use for a base, whether wire mesh is necessary, and more!
What type of concrete should I use for my driveway?
The type of concrete you use depends on how much time and labor you want to mix and pour the concrete. There are three basic types of concrete:
- the concrete you mix yourself, which consists of cement, sand, and gravel or aggregate
- ready-mix concrete from your local building supply
- delivered, ready-to-pour concrete, which arrives mixed and is poured directly into your forms
Mixing Concrete
Mixing your own concrete is the most labor-intensive as you will need to measure the concrete, sand, and gravel or aggregate, mix the appropriate amount of water, and pour the concrete into your frame. You can purchase the concrete, sand, and aggregate at your local building supply. You may also be able to purchase the sand and aggregate directly from a local quarry.
If you are mixing your own concrete, the best ratio for a driveway is a 1:3:5 ratio; one part cement, three parts sand, and five parts coarse aggregate. This provides for a strong concrete pad. The aggregate gives your concrete its strength and stability. This method is usually done in small batches with a cement mixer and can take a considerable amount of time.
Ready-Mix Concrete
The ready-mix from your building supply store is less labor and time-intensive as it only requires you to add the appropriate amount of water, mix and pour. Many brands are ready to use concrete mixes that can be purchased at your local building supply and typically come in 60- or 80-pound bags.
The ready-to-use concrete mixes only require adding water. The concrete used should have a strength of at least 4,000 pounds per square inch. This information is usually listed on the packaging. This method is also done in small batches and requires a considerable amount of time.
Ready-to-Pour Concrete
The ready-to-use delivery concrete is the least labor-intensive and time-consuming. This concrete is delivered ready to pour and is poured directly into your framework. The pouring process for this is usually 1.5 hours or less for an average driveway.
Do you need wire mesh in a concrete driveway?
Wire mesh is not necessary for lighter usage driveways; however, it is recommended. Wire mesh is recommended for concrete slabs four to five inches thick when the driveway used is for passenger vehicles. For heavier vehicles, wire mesh is necessary.
The use of mesh provides a stronger concrete driveway, and while it will not prevent cracks, the wire mesh will hold the cracks together, providing a longer life to your concrete driveway. For concrete driveways five inches or thicker, half-inch steel rebar is recommended to provide greater strength and durability to the driveway.
How deep do you need to dig for a concrete driveway?
You should dig 8-16 inches for a driveway, depending on the usage, soil, and slope of the driveway. Driveways for heavier vehicles should be 12-16 inches. For lighter vehicles, it should be 8-12 inches. If your soil is sandy, you should go with 10-12 inches of gravel base for all vehicles. A gravel base for a driveway should be 4-12 inches.
How thick should aggregate be under a concrete driveway?
The aggregate or gravel under a driveway should be four to 12 inches. Gauge aggregate depth based on vehicle weight, slope, and base soil. Once you have dug down to the appropriate depth, you should lay a foundation of aggregate, making sure to compact the aggregate to provide a firm base.
- The heavier the vehicle(s), the deeper the gravel should be. This is important to avoid damaging the concrete.
- While your driveway should have a slight incline to promote water runoff, if you have a fairly steep incline, you will need a deeper base to prevent shifting and cracking due to gravity and pressure.
- Sandier soil needs a deeper base to support the concrete and avoid shifting under the concrete driveway, damaging the concrete causing cracks.
To learn more about driveway slope, read "How Steep Can A Driveway Be?"
Summary
The thickness of your concrete driveway is typically four to five inches, with four to 12 inches of aggregate base underneath. The depth and thickness depend on driveway usage and the depth and slope or incline. Your basic concrete driveway on level ground for passenger or light SLU vehicles would be, in total, eight inches deep, consisting of four inches of gravel or aggregate and a four-inch concrete slab with or without wire mesh.
The use of wire mesh is recommended but is not required for concrete driveways, but it does strengthen your concrete, providing greater durability. As long as your concrete has a 4,000 psi rating and the proper cement to sand to gravel ratio, the type of concrete you use will depend on how much time and labor you want to put into the project.
If you aren't sold yet on concrete, read "How Long Does An Asphalt Driveway Last?"