How To Locate Rebar In Concrete

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The concrete surface is generally smooth in texture without any roughness. But, you might come across quite a lot of harmful materials within the concrete mixture. Therefore, before you intend to cut or drill through a concrete surface, it is important to check for those materials underneath it.

One such material is rebar, damaging the tools and destroying machinery pieces if you do not carry out a prior inspection. 

How To Locate Rebar In Concrete

Rebar within concrete can result in structural hassles and physical injuries and might also delay the projects. Hence, you need to check for rebar to carry out the concrete applications effortlessly. However, there is no necessity of digging the entire concrete surface to locate rebar as there are specific tools for it.

Workers trying to build a building from the ground up

Earlier, the contractors and experts used specific x-ray machines to check for rebar. But now the technology has developed, and people have more efficient tools to serve the purpose. 

Today, the use of a ground-penetrating system with radar is preferable for detecting rebar underneath the concrete. But, you need to get an idea of using it! Therefore, follow this guide to know how to locate rebar in concrete

Method 1: Using Radar System To Scan The Concrete

To begin with, you need to be aware of the radar system. The steps are:

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Step 1: Buy The Ground Penetrating Radar Unit Or Rent It

  1. This tool is also known as GPR and is affordable for people to buy. If you have frequent applications with concrete materials, then it is better to purchase. But, if you are willing to use it only once, then you can rent it too. 
  2. GPR cart has the potential to send certain radio waves through concrete surfaces. It bounces off when it comes in contact with the rebar and returns to the sensor. The cart then makes an ideal chart through the display to ensure that you get an idea of rebar depth and location. 
  3. The cost for a ground-penetrating radar unit is usually USD 1000, which is cheaper than other tools. 

Step 2: Setting The GPR Cart

  1. Now, you need to set the GPR cart alongside the edge of the concrete surface. 
  2. Do it by placing the cart at the bottom-most region of the working area. 
  3. Once you have done that, you can turn on the equipment. Wait for the display to turn on completely. 
Man trying to align reinforced steel rods  as a foundation for a building

Step 3: Running The GPR Cart Across The Concrete Surface

  1. Get hold of the handle, and push the GPR cart towards your left. 
  2. Horizontally keep the motion. 
  3. Keep a check on the display over the system. 
  4. Check if you observe any surges or curves within the display screen. 
  5. Keep the cart moving forward until the chart within the display is full of figures. 
  6. Stop moving the cart, right at the exact spot over the concrete surface, when the chart on display is full. It is because the chart will keep on adding new information and eliminate the earlier ones. So, you might lose information!
  7. The scan length of a usual GPR cart is 6.1m or 20 feet. But, it might vary depending upon the models. 
  8. Now, move the cart backward until the cursor gets aligned with the curve’s top over the display. In this motion, you will have to move the cart towards the right end side of the work area. It is to ensure that the cart remains on the right path. 
  9. Check the region where the curve’s top intersects within the rulers over the display. It will give you an idea about the depth. 
  10. Mark the concrete surface at the point where the GPR cart lights the area up with a laser. 
  11. Continue the backward motion of the cart to keep marking the rebar locations over the concrete surface. 
  12. Now, move the cart up by 6 inches or 15cm to scan the horizontal rows. 
  13. Run the cart in a vertical motion this time, and find the crossbars over the surface. 

To take a glimpse at the visual demonstration of this method, check out this YouTube video now

Method 2: Locating Rebar By Using Handheld Locator

If you are finding the GPR cart a bit complex, you should consider using the handheld rebar locator for this purpose. Here are steps for the same:

Construction workers trying to locate the rebar in their construction
  1. First, you need to go ahead and buy a handheld rebar locator. It is cheaper than GPR but is not that accurate. You need to spend only around $200 on it. But, you can also rent it, if you do not need it so frequently. 
  2. Hold the handheld locator, in a flat formation, against the surface. Now, you can turn it on! 
  3. You will have to slide the locator in a horizontal motion over the concrete surface. 
  4. Now, you need to keep up the motion until you hear the beep sound from the device. 
  5. Mark that location, where the locator beeps, with the use of a marker or chalk. 
  6. Note down the depth measurement from the chart shown over the display. 
  7. Now, continue moving the locator, and keep marking the concrete while moving along the horizontal rows. 
  8. Then you can move the locator again in a vertical motion to find the crossbars. 

Frequently Asked Questions

Why Do You Think Concrete Gets Stronger With The Presence Of Rebar In It?

Rebar is an enforced steel rod that is embedded within concrete surfaces to make them durable. Concrete without rebar is very prone to experience faster damage due to tensile stress. Hence, without rebar, a concrete surface is inefficient in fighting against threatening forces.

To know more about the same, you can refer to this article that describes practical engineering associated with concrete and rebar. 

Can I Use A Metal Detector For Locating The Rebar?

Yes, you can use a metal detector, which might be an alternative if you don’t have the other two tools. A metal detector will give you an insight into where the rebars are, but you won’t get the depth and additional information. 


So, put an end to your urge to hire a professional for carrying out this job. Instead, learn everything about using the right tools to ensure high accuracy in your measurements. It will make your concrete drill applications easy and will increase the durability of your drilling tools.  

An expert at home repair, remodel, and DIY projects for nearly 40 years. His first experience came in completely restoring an antique home. Completely redone from the inside out, and restored to its original form, the home is a featured design by renowned Southern California Architect Cliff May, considered to be the father of the California Ranch Home. Now Dennis spends his time on fine woodworking projects and tool comparisons.