Do Driveways Need Rebar? (Reinforcing Bar)

Do Driveways Need Rebar Reinforcing Bar

Before you can answer that question you should know what rebar is and why you might need to use it for your driveway.  One important thing to remember is that your driveway has to be sturdy enough to support the cars and trucks parked there. 

The driveway should last the life of your house and be well constructed.

What is Rebar?

This is the shortened name for a reinforcing bar and is generally made of steel.

For over 150 years, it has been used to reinforce concrete construction of all types, not just driveways. 

This is made from different grades of steel and alloys.  It is manufactured with ridges so that when concrete is poured onto the bars, it will be easier for the concrete to adhere to the rebar. 

Generally, they use stainless steel because it is resistant to rust.

Why Does Your Driveway Need It?

Slabs made out of concrete are very highly prone to cracking. 

When you add rebar, it will help to prevent these cracks from widening, which is due to sections of the cracked concrete slabs moving apart. 

Typically, your concrete slabs for driveways are four inches thick but they can be up to six inches. 

These extra inches give additional support for larger trucks and other heavy vehicles. Instead of rebar, some use welded wire mesh.

Mesh Versus Rebar

Since both of these can be used as reinforcement for concrete driveway slabs, which one is best?  Welded wire mesh consists of galvanized panels of welded wire, which can reinforce your driveway. 

Unlike rebar that can be used for driveways for heavy vehicles, the welded wire mesh is better for driveways that are generally not driven on by heavy vehicles. 

Welded wire mesh is less expensive than rebar and thinner so it is mostly used for driveway concrete that is four inches thick. 

When deciding where to use rebar or welded wire mesh, consider the thickness of the driveway and the type of vehicles you are parking on the driveway.

How to use Rebar

Generally, rebar is used to reinforce driveways that are five to six inches thick. 

When rebar is used, it needs to be laid slightly above the center or in the center of the thickness of the slab, with a spacing of 12 inches.

When a professional is pouring your driveway they will prop up the rebar grids on special plastic or metal supports. 

These are called chairs but you can also bricks or other scrap material.  The drawback to not using the properly made supports is that anything else could cause weak spots in the concrete slabs. 

The grids of rebar are constructed by laying the rebar pieces in a perpendicular pattern making sure there is even spacing. 

At each intersection, the bars are tied together with metal wire. 

The edges of the grid need to be kept at equal distances from all sides of the concrete slab.  Throughout the slab, the minimum coverage of concrete has to be maintained.

Calculating Rebar

Most people will have their driveways professionally poured so that it is done correctly.

In some areas, there might be local and state building codes that pertain to concrete driveways. 

If you plan to pour your driveway you need to check to see if there are codes you need to follow. 

That is why many hire professionals so they do not need to worry about codes.

  • Step 1:  You need to measure the entire length and width of the driveway you are going to pour.
  • Step 2:  To determine the number of crossing bars you would need you will have to divide the width dimension of the driveway.  Generally, these are spaced between 18 and 24 inches apart and use three-eighth inch rebar in the grid.  At each end of the driveway grid, you need to add another crossing bar.
  • Step 3:  Take the crossing bars you calculated in the previous step and multiply them times the driveway’s width minus 12 inches.   This will give you the total linear quantity of rebar that you are going to need for the crossing bars.  When you take the 12 inches deduction from the total width, it will allow for a six-inch gap on each side.  This space will be between the edge of the driveway concrete and the rebar.
  • Step 4:  To determine the number of crossing bars you will need, divide the length of the driveway by the rebar grid spacing.  You also need to add one extra for each side of the grid.
  • Step 5: Take the number of bars you calculated in the step above and multiply them by the length of the driveway minus 12 inches.  This will give you the total linear quantity of rebar that you will need for the lengthwise bars.  The deduction will allow a six-inch gap on each end of the grid between the edge of the driveway and the ends of the rebar.
  • Step 6:  In steps three and five, add the total linear quantities in each step and then divide the total by 20.  This will determine how many standard 20-foot lengths of rebar that you will need to reinforce your poured driveway.

Conclusion

  • Using rebar will give your concrete driveway support but it will not prevent cracks.  The rebar will help hold the slabs together if they do crack.
  • As you can see, there are a lot of steps in laying your rebar and pouring your driveway.  That is why most will hire a professional to pour their driveway.  The professionals know how to lay it out correctly and know the codes if any.
  • You need to make sure that rebar is in your driveway concrete because if now it will crack and possibly move around and even sink into the ground.
  • When rebar is used in driveways it helps to reduce just how thick you have to pour the concrete so thicker layers can be used but it is still strong.
  • Rebar helps the concrete driveway to last longer because it provides strength.

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