Practical Gardening: Drill Trellis Anchors in Concrete Wall

After marking the drill points for the trellis anchors on the concrete wall, it's time to take out the power drill for a spin. As you will be working on concrete, ensure the power drill is switched to the "hammer drill" setting and not the "normal drill" setting which works for metal and wood only.

In this connection, you should also be ready with the appropriate masonry drill bit to be used for drilling holes on the concrete wall. Masonry drill bits, as opposed to the regular drill bits, will work only on concrete.

Because you'll be screwing the trellis anchors into the holes, you'll also be needing plastic expansion shields. These are also called plastic expansion sleeves or fasteners. One expansion shield used in this garden project is shown below.

Prepare the Drill Hole for the Expansion Shield

The drill hole that needs to be made should be deep enough to accommodate the expansion shield. Some power drills have a measuring gauge/rule to get the correct depth, but if your power drill doesn't have that, there's a way to obtain the correct drill hole depth.

Ideally, the open end of the expansion shield should be flush with the wall's surface, when fully inserted. See the sample below.

If the expansion shield's open end protrudes (hole not deep enough), the plastic piece will protrude even further when the trellis anchor is screwed in. The excess plastic material that sticks out then needs to be removed with a blade cutter. This is especially so if the garden trellis is to be painted.

On the other hand, a hole that's too deep will embed the expansion shield deeper inside, leaving a depression at the surface and compromising the stability of the trellis anchor.

Also, be sure to use the right diameter masonry bit. The drill hole should be just big enough to allow the expansion shield, but remain snug inside.

If the expansion shield is not snug inside the hole, it won't grab the surrounding concrete. Instead, it will turn with the trellis anchor as the anchor is screwed in. This will loosen the hole even further.

Screw in the Trellis Anchor

Position the trellis anchor so it's perpendicular to the plane of the wall's surface. Slowly screw it in as shown below.

Hold the trellis anchor with one hand to maintain the trellis anchor's position, as you screw it in with the other hand.

Depending on the porosity of the surrounding concrete and the size of the hole, some trellis anchors may pose a challenge and will be hard or tight to screw in. In this case, use a pair of locking vise grips. Lock the vise grip lightly on the other end of the trellis anchor. Slowly turn the vise grip clockwise while maintaining the perpendicular position as shown below.

Again, you may need to assist the turning by holding the trellis anchor with you other hand. Ensure that it doesn't wobble as the trellis anchor is screwed in.

Once you have started screwing the trellis anchor, resist the temptation of unscrewing it. Doing so increases the chance of loosening the drill hole. Also remember, that when the shield expands, it will split. If you fully unscrew the trellis anchor, check if the expansion shield is still usable. Otherwise, replace it with a new one.

Shown below is a trellis anchor that was successfully fastened to the wall.