How to Install Anchor Bolts in a Slab

Updated February 21, 2017

Concrete anchor bolts or expansion bolts are used to provide a strong structural connection to concrete. Many factors contribute to the anchor bolt holding in the concrete. You need to ensure that you drill the proper sized hole in the concrete, that you thoroughly clean the hole before you install the anchor bolt and that you properly torque the hex nut to force the sleeve of the anchor bolt into the concrete. If you follow the installation instructions, you will have the full holding power of the anchor bolt.

Assemble an anchor bolt from the anchor bolt kit. This includes sliding a flat washer onto the anchor bolt and then threading a hex nut onto the end of the anchor bolt.

Hold the assembled anchor bolt against the manufacturer recommended size masonry drill bit and align one end of the anchor bolt with the tip of the drill bit.

Wrap electrical tape at the point where the other end of the anchor bolt ends on the masonry drill bit. This is the drilling depth of the in the concrete.

Secure the marked masonry drill bit into the chuck of the hammer drill and put on your safety glasses.

Place the tip of the masonry drill bit onto the surface of the concrete at the location you need to install the anchor bolt.

Pull the trigger of the drill motor while applying pressure toward the concrete with the hammer drill. Stop drilling when the electrical tape that you wrapped around the masonry drill bit contacts the surface of the concrete.

Insert the plumber's wire brush into the hole you drilled into the concrete with the masonry drill bit and twist the handle of the wire brush as you pull it from the hole to remove the concrete dust from the hole.

Slide the nozzle of the hand-held air bulb into the concrete hole and press the bulb 10-15 times to remove the loose dust from the drilled hole.

Place the sleeved end of the anchor bolt into the cleaned hole and tap the hex nut with the hammer to work the anchor bolt into the concrete hole.

Secure a socket from the socket set that matches the size of the anchor bolt hex nut onto the 3/8-inch torque wrench.

Set the socket onto the hex nut and turn the torque wrench handle clockwise to tighten the hex nut and wedge the anchor bolt into the concrete hole.

Reverse the direction you are turning the torque wrench handle to loosen the hex nut and complete the installation of the anchor bolt.

Things You'll Need

  • Anchor bolt kit
  • Masonry drill bit
  • Electrical tape
  • Hammer drill
  • Safety glasses
  • Plumber's wire brush
  • Hand-held air bulb
  • Hammer
  • Socket set
  • 3/8-inch torque wrench
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