When drilling a hole into the base material of concrete, brick, or block, the hole must be bored 1/2 inch deeper than the concrete anchor will penetrate. The extra depth of the hole ensures that the anchor does not bottom out and provides space for any dust generated during the drilling operation. The hole should be large enough to allow the insertion of a sharp object (such as an anchor gun) without scraping it on the inside wall of the hole. It is best if the hole can be seen from above; however, this is not always possible so an unobstructed view from all angles while working below ground level is recommended.
If you are installing more than one anchor, leave at least 1/2 inch between each one. This allows enough room for each one to be properly drilled.
The depth of your concrete anchor depends on what type of anchor you are using. We will discuss several options in subsequent chapters. For now, it's important to understand that most concrete anchors need to be at least 3/4 inch deep to provide adequate support. One option for shallow anchors is the spiral drill hole design. These anchors work by injecting plastic into the center of the concrete with small holes along the side walls of the spiral pattern. As the spiral moves downward, it leaves no gap between holes, creating a solid mass of plastic in the center of the anchor. This type of anchor requires no more than 1/4 inch of penetration into the concrete.
Diameter and depth of the hole A 5/8" concrete wedge anchor necessitates the drilling of a 5/8" hole in the concrete. The hole in the concrete must be bored at least 1/2" deeper than the concrete wedge anchor will penetrate. The bolt should be placed in the center of the hole to provide maximum holding power.
The anchor should be placed in the concrete with the washer facing up. If necessary, use a hammer to tap the end of the anchor into the concrete to get it started in the right direction. It may take several attempts to get this process right so don't force the issue if you hit rock solid concrete instead try again later with a slightly larger drill bit or masonry bit.
Once the hole is drilled, the bolt should be inserted until it is completely covered by the washer. This will prevent the bolt from coming out of the concrete once it has set. If more security is needed, add another washer. It is recommended that you put some kind of a sealant on the inside of the hole after inserting the wedge anchor to keep out any moisture which could cause the concrete to crack over time.
Wedge Anchor—only for use in concrete Drill a hole 1/2 inch deeper than the anchor's penetration depth into the concrete, ensuring that the minimum embedment criteria are satisfied. While the fixture is in place, the hole may be drilled.
To ensure proper drainage, install a French drain or let water flow through an underground conduit or gutter during and after construction.
Wedge anchors are designed to hold only tension loads. To prevent them from pulling out of soft soil, insert a metal rod into the hole before pouring concrete. The tip of this metal rod should be below ground level by at least 1-1/2 inches. Tie one end of a rope or cable to this tip and then pull on the other end to set the anchor in place.
The hole needed to install wedge anchors is relatively large (at least 3/4 inch in diameter), so they are not recommended for use in lawns or gardens where space is limited. They also require concrete with a high early-age strength because the anchor needs to be fully embedded before the concrete sets.
The depth that you drill depends on the type of wedge anchor you are using. For example, some anchors need to be embedded only to their top edges while others must be completely submerged. In either case, the maximum allowed embedment is 1-1/2 inches.
When placing a wedge anchor, a minimum of 2-1/2 inches must be embedded in the concrete. There should be at least an inch of exposed material for the attaching material to latch onto. For example, if using wire mesh, the minimum depth is 3-1/4 inches.
The more deeply you embed a wedge anchor the more resistance you will feel when driving the anchor into the ground. This helps to prevent the anchor from being pulled out of the concrete once it's been drilled into place.
Wedge anchors are commonly used to attach fencing, signs, and light posts to hard surfaces such as concrete or stone. They provide a large surface area for bonding, which means less adhesive is needed than for other anchoring methods such as screws or bolts. This also means that wedge anchors are particularly well suited for outdoor use where corrosion may occur.
Wedge anchors come in two basic sizes: 1-inch and 2-inch. The size you choose depends on how much force you expect to apply to the object being attached to the fence or sign post. If you plan to drive the anchor very deeply, then using a larger one will help to avoid tearing out the bottom of the hole while still providing enough resistance to prevent movement.