# How do you drill into concrete? Drilling into concrete takes a hammer drill and a carbide-tipped masonry bit, steady pressure, and dust control. Mark the spot, start slow on low speed, then let the hammer action do the work. Drilling releases respirable silica, so OSHA's Table 1 pairs handheld drills with a dust-collection shroud and a HEPA vacuum. ## Short version - A hammer drill or rotary hammer does this job; a standard drill will burn up trying. - Use carbide-tipped masonry bits, and SDS-Plus or SDS-Max shanks on a rotary hammer. - Start on low speed to keep the bit from wandering, then apply steady, moderate pressure. - Control the dust — OSHA sets the silica PEL at 50 µg/m³ and the action level at 25 µg/m³ as 8-hour averages. - If the bit stops advancing and starts squealing, you are on rebar; stop and move over. ## What drill and bit do you need? A hammer drill is the minimum tool, and a rotary hammer is the right one past about ½ inch or a few inches of depth. Both add a percussive blow to the rotation, which is what actually breaks the concrete at the bit face; a standard drill only spins, so it polishes the hole and cooks the bit. Rotary hammers use SDS-Plus or SDS-Max shanks that transmit the hammer energy directly to the bit rather than through a chuck. Bits must be carbide-tipped masonry bits, not wood or metal bits. Manufacturers such as Hilti and Bosch publish bit systems matched to their tools, and their instructions govern bit selection, speed, and the depth of hole a given bit is designed for. For anchors, the bit diameter is not a choice at all — the anchor's published instructions specify it, and the matched bit is often sold with the anchor. Hardness varies more than people expect. A 30-year-old driveway with river gravel drills differently than a modern slab with crushed granite, and hitting aggregate mid-hole slows progress without meaning anything is wrong. ## How do you keep the silica dust out of your lungs? Drilling concrete generates respirable crystalline silica, which is the reason OSHA regulates the task under 29 CFR 1926.1153. The standard sets a permissible exposure limit of 50 µg/m³ and an action level of 25 µg/m³, both as 8-hour time-weighted averages. Employers can comply by following Table 1, which pairs specific tasks with specific controls. For handheld and stand-mounted drills, including rotary hammers, Table 1 specifies a drill equipped with a commercially available shroud or cowling with a dust collection system, plus a HEPA-filtered vacuum when cleaning holes. Follow that and no respirator is required for the task. By contrast, jackhammers and handheld chipping tools require either continuous water at the point of impact or a shroud with dust collection, and add respirator requirements indoors or beyond four hours. The standard also bans dry sweeping and dry brushing where a wet method or HEPA vacuuming is feasible, restricts compressed air for cleanup, requires a written exposure control plan, and requires medical surveillance for employees who must wear a respirator 30 or more days a year. OSHA's rules bind employers and their workers, not a homeowner drilling four holes in a garage wall — but the dust is chemically identical, so a shop vacuum with a HEPA filter held at the hole is worth the two minutes it takes to set up. ## How do you drill the hole? Mark the location and give the bit a starting point. On smooth or troweled concrete, a masonry nail or a center punch makes a divot that keeps the bit from walking, which matters because a wandering bit ruins the layout and chips the surface. Start the drill at low speed with the hammer function off or the drill barely rotating, just deep enough to establish the hole. Then bring it up to speed and hold the tool square to the surface with steady, moderate pressure. Leaning on it does not drill faster; it overheats the carbide and, on a rotary hammer, works against the hammer mechanism. Back the bit out every inch or so to clear the dust, especially in deep holes, because packed dust slows cutting and heats the bit. Set your depth with the tool's depth rod or a wrap of tape on the bit. If you smell hot metal or see the tip glowing, stop and let it cool — carbide loses its edge to heat, and a dulled bit is why the second hole always takes longer than the first. ## What happens if you hit rebar? Stop as soon as the bit quits advancing. Reinforcing steel usually sits under 1.5 to 2 inches of cover in ordinary construction — CIP 25 gives 1.5 inches as a general minimum and 2 inches where deicing salts are used — so a hole deeper than about an inch and a half can find it. Do not force through it. Cutting reinforcement reduces the capacity the bar was placed to provide, and in a beam, a suspended slab, a retaining wall, or a post-tensioned slab it can be genuinely dangerous. Move the hole two inches and try again, or scan the area first with a rebar locator or ground-penetrating radar for anything structural or heavily reinforced. Rebar-cutting bits exist and have legitimate uses in demolition and coring, but they are the wrong answer for a homeowner fastening a shelf. *General information, not engineering advice. Structural work should be designed by a licensed engineer.* ## How deep, how wide, and why does the hole need cleaning? The anchor decides the hole, not the fastener you have in hand. Every mechanical or adhesive anchor publishes a required bit diameter, minimum embedment depth, and hole preparation procedure, and for anchors used in structural applications those values come from an ICC-ES evaluation report. Drill deeper than the embedment so debris has somewhere to go, and use the manufacturer's stated hole depth as the minimum, not the target. Cleaning is the step that gets skipped and the one that costs the most capacity. Dust left in the hole acts as a bond breaker for adhesive anchors and as a lubricant for mechanical ones. Vacuum, brush, vacuum again — which is exactly what Table 1 asks for anyway with its HEPA-filtered vacuum for hole cleaning. Once the hole is right, the fastener choice follows. See [how to screw into concrete](/questions/anchoring-and-fastening/how-to-screw-into-concrete/) for concrete screws and anchors, or [how to hang pictures on concrete walls](/questions/anchoring-and-fastening/how-to-hang-pictures-on-concrete-walls/) for light loads. ## Common mistakes - **Using a regular drill** — it will not break the concrete face, and you will destroy the bit and the motor before you finish one hole. - **Drilling dry with no dust capture** — this is the task OSHA wrote Table 1 for, and the dust is silica whether or not anyone is inspecting. - **Pushing harder when progress slows** — heat kills carbide; back out, clear the dust, and let the hammer work. - **Forcing through rebar** — cutting the bar removes exactly the capacity it was placed to provide. - **Setting an anchor in a dirty hole** — drilling dust left behind is the most common reason an anchor pulls out under a load it was rated for.