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Concrete block is easier to drill than poured concrete, but it still punishes the wrong bit, excessive pressure, and poorly chosen anchors. A cordless hammer drill is usually the right tool for small holes for shelves, conduit, hose reels, and light fixtures. The key is matching the drill, bit, hole size, and anchor to the block rather than treating every masonry wall the same way.
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Choose the right drill
For occasional holes up to about 1/2 inch in diameter, a standard cordless drill with a masonry bit can work, especially in soft cinder block. It will be slower and may overheat, but the cheaper option is fine for a few small holes. Turn the hammer function off if the drill does not have one; pressing harder does not make a regular drill behave like a hammer drill.
A cordless hammer drill is the better general-purpose choice. Its hammer action chips the masonry as the bit rotates, reducing the force you need to apply. Look for a variable-speed trigger, a two-speed gearbox, and a side handle. An 18V or 20V-class tool is adequate for most homeowner work. Use the low gear for large holes and the higher gear for small holes, following the drill manufacturer’s speed guidance.
Do not confuse a hammer drill with a rotary hammer. A rotary hammer uses an SDS bit and delivers much stronger impact energy. It is the right choice for repeated drilling, holes larger than 1/2 inch, or very hard block and mortar, but it is heavier, noisier, and unnecessary for installing a few wall anchors.
| Tool | Best use in block | Trade-off |
|---|---|---|
| Regular cordless drill | A few holes up to about 1/4 inch | Slow; more heat and bit wear |
| Cordless hammer drill | Most anchor holes from 1/4 to 1/2 inch | More vibration and noise |
| Rotary hammer | Many holes, large holes, or very hard masonry | Costlier and less convenient |
Select the right masonry bit
Use a carbide-tipped masonry bit, not a wood, metal, or multipurpose bit. The bit diameter must match the anchor package, not merely the screw diameter. A 1/4-inch masonry bit is common for small plastic anchors, while larger sleeve, hammer-drive, and concrete screws may require 5/16-, 3/8-, or 1/2-inch holes.
A basic carbide-tipped masonry bit set is adequate for occasional work. Premium bits cut faster and last longer, but buying an expensive set makes little sense if you are drilling four holes in soft block. Replace a bit when the carbide tip is rounded, the hole becomes noticeably undersized, or drilling speed drops despite proper technique.
Check the block before drilling. Concrete masonry units are hollow, with stronger webs and face shells surrounding open cavities. The mortar joint may be easier to drill but is often a weaker fastening location. For a light load, a hollow-block anchor can be appropriate. For a heavier load, aim for the solid web or use an anchor system specifically rated for hollow masonry.
Prepare and drill the hole
First, check for electrical cables, plumbing, and other hidden services. Do not drill where you cannot reasonably rule them out. Mark the location with a pencil and apply a small piece of painter’s tape if the block face is dusty or prone to chipping.
Measure the anchor length and mark the bit with tape about 1/4 inch deeper than the required hole. The extra depth gives dust somewhere to collect, but avoid drilling needlessly deep. Keep the drill perpendicular to the wall. A tilted hole can prevent the anchor from seating fully and can leave the screw pulling at an angle.
Set the drill to hammer mode and start slowly. Let the carbide tip establish a shallow depression before increasing speed. Use firm, steady pressure, but do not force the bit. For a 1/4-inch hole, expect roughly 10 to 30 seconds in ordinary block; harder aggregate may take longer. Withdraw the bit every few seconds to clear dust and reduce heat. If the bit becomes too hot to touch, stop and let it cool.
Near the final depth, ease off the pressure. This helps prevent breaking through the back of a thin face shell and reduces chipped edges. If the bit suddenly drops into a cavity, stop pushing. You may have entered a hollow cell rather than solid material, so reassess the anchor choice instead of simply making the hole larger.
Clean the hole and install the anchor
Dust left in the hole is a common reason anchors spin or pull out. Remove it with a vacuum, a hand pump, or several bursts of compressed air while wearing eye protection. Do not blow masonry dust toward your face. Brush the hole if the anchor manufacturer recommends it.
For light items such as small signs or cable clips, plastic expansion anchors can be sufficient when installed in solid material. In hollow block, use an anchor designed for hollow masonry rather than assuming a standard ribbed plug will expand correctly. For heavier shelves or equipment, compare the manufacturer’s load rating and install into a solid web where possible.
Concrete screws and masonry anchors offer different advantages. Concrete screws are removable and provide a strong hold in solid block, but they need the exact pilot-hole size and enough embedment. Plastic anchors are inexpensive and forgiving for light-duty jobs, but they can spin in oversized or dusty holes. Hollow-wall toggle-style masonry anchors spread their load behind the face shell, though they require more clearance and are harder to remove cleanly.
Avoid common failures
If the hole is too large, do not pack it with scrap wood, paper, or random filler. Move the fastener to a new location or use a larger anchor approved for the material. If the anchor spins while tightening, remove it and inspect the hole; continued tightening usually makes the damage worse.
If the block cracks, you may have drilled too close to an edge, used excessive pressure, or selected an anchor that expands too aggressively. Keep holes at least 2 inches from unsupported edges when practical, and follow the anchor manufacturer’s edge and spacing requirements. Wear safety glasses, hearing protection, and a dust mask suitable for masonry dust. Hold the side handle with both hands when using larger bits, because the bit can bind suddenly.
For a few small, lightly loaded holes, a basic cordless hammer drill and inexpensive carbide bits are enough. Spend more on a rotary hammer, premium bits, or engineered anchors when the job involves many holes, hard aggregate, large diameters, or a load that would be costly or dangerous to lose.