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Tips and Tricks Lag Shield

Installing Lag Shields: Step-by-Step Instructions

Purchase Lag Shield Anchors

Nothing says ‘summer’ quite like grilling. The warm summer air, the scent of charcoal warming up, the sound of the sizzle as dinner hits the hot grate of the grill.

Any homeowner who loves outdoor entertaining takes pride in their house’s patio. Permanently installing a grill onto a concrete patio is a great way to make a customized oasis in the back yard. For this sort of installation, lag shields are often used. 

Lag Shields

Lag shields are fasteners that can be installed in lots of base materials—both harder, denser base materials and softer base materials. Manufactured from a die cast Zamac alloy, the lag shield is designed for use in conjunction with a lag screw. Lag screws are always sold separately. 

Radial ribs help provide holding values in both hard and soft base materials. Each diameter of shield comes in two different versions of short or long.

Learn how to install lag shields

1. Setting Up

  • Drilling into base materials like concrete, brick, block, or mortar requires the use of a hammer drill. The hammer drill must be switched to the hammer and rotation mode to achieve optimum drilling performance. 
  • The hammer motion of the drill pulverizes the base material and the rotation removes the dust from the hole. The use of a rotation only drill will not work because the hole created will not meet hole and anchor tolerance requirements.
  • The bit used with the hammer drill must be carbide tipped and meet ANSI standards. An ANSI standard carbide tipped bit will ensure match tolerance between hole size and shield anchor diameter requirements. The diameter of the bit used for a shield is equal to the outside diameter of the shield and not the designated diameter or inside diameter.

Hole Requirements for Lag Shields


Designated Diameter of Lag Shield

Diameter of Carbide Bit

1/4” 1/2”
5/16” 1/2”
3/8” 5/8”
1/2” 3/4”
5/8” 3/4”
3/4” 1”


2. Get Drilling

  • Minimum embedment for the shield in any base material is equal to the length of the shield being installed. Most applications require the shield to be flush with the surface of the base material. Make sure that the hole is drilled to a depth at least equal to the length of the shield being installed. The shield can be embedded into the base deeper than minimum embedment, which can provide higher holding values along with a need for a longer screw.
  • To achieve the correct depth of the hole, use the depth gauge provided with the hammer drill. If the depth gauge is not available, then wrap a piece of tape around the bit at the correct drill depth. When using the keyless chuck type hammer drill, make sure that the drill bit is in the most protracted position before placing the tape or locking in the depth gauge.

3. Light House Keeping

  • The hole must be cleaned of all dust and debris before the shield is inserted into the hole. Use a wire brush the same diameter as the hole in an up and down and turning movement. Vacuum the hole, and then repeat the process to ensure that the hole is ready for the shield to be inserted. Compressed air is sometimes used for blowing the debris out the hole, but this can create a lot of dust in the air and so may not be suitable for many situations.

4. Install the Lag Shield and Lag Screw

  • The length of the screw used with the shield is critically important in ensuring that the shield is properly expanded. The length of the screw must be the depth of embedment of the shield plus the thickness of the material being fastened plus space for any washers.
  • Install the shield in the base material by holding the open end of the shield and inserting the closed end into the drilled hole. A light tap with a hammer may be needed to set the shield flush with the surface of the base material.
  • Move the item to be fastened over the shield so that the hole in the item lines up with the shield. Insert the correct length screw through the fixture and into the shield. Tighten by hand.
  • Using a wrench, turn the screw clockwise until the head of the screw is tight against the surface of the item being fastened. Make sure the screw is not over torqued, as this may cause the shield to spin in the hole and lose its holding values.