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Choose the right bit for the screw
Tapcon-style concrete screws need a pilot hole drilled to the diameter and depth specified for that screw. The common 3/16-inch screw typically calls for a 5/32-inch carbide-tipped bit; a 1/4-inch screw typically calls for a 3/16-inch bit. Check the fastener package before drilling: sizes and instructions can vary, and using a bit that is too large can leave the screw with too little material to grip.
For a few holes in ordinary concrete or brick, a basic 5/32-inch carbide-tipped masonry bit is often enough. Buy the diameter that matches the screw instructions, not a bit marketed as “close enough.” If the package specifies a particular bit, follow that guidance.
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What type of bit works best?
Use a carbide-tipped masonry bit with a round shank for a standard drill chuck. These are inexpensive and suit occasional installations. A hammer drill’s pulsing action helps the carbide tip break up concrete while the cutting edges clear the dust. In brick, especially soft or old brick, start without hammer action if you can; pounding can crack or crumble the material.
SDS-Plus bits are built for rotary hammers, not ordinary three-jaw chucks. They are a good choice when you have many holes, hard concrete, or a rotary hammer already on hand. For a small repair, buying an SDS bit without an SDS tool makes no sense. Likewise, a premium bit may last longer, but it will not rescue an oversized hole or a worn-out drill.
For repeat work, consider a set of correctly sized SDS-Plus masonry bits if your rotary hammer accepts SDS-Plus shanks. Confirm both the shank type and the required hole diameter before ordering.
Bit options at a glance
| Bit type | Best for | Trade-off |
|---|---|---|
| Standard carbide masonry bit | A few holes with a hammer drill | Cheapest; can cut slowly or wear quickly in hard concrete |
| Higher-quality carbide hammer bit | Repeated holes or dense concrete | Costs more, but usually stays sharp longer |
| SDS-Plus masonry bit | Rotary-hammer work and larger batches | Requires an SDS-Plus tool; will not fit a regular chuck |
Set diameter and depth before drilling
The hole must be deep enough for the screw to enter fully, plus room for dust at the bottom. Follow the package’s stated depth; do not assume the screw’s length is the drilling depth. A stop collar or tape flag makes a useful visual marker, though a collar is more consistent. Keep the bit straight and let the tool do the cutting rather than forcing it.
Concrete dust left in the hole can stop the screw early, bind the threads, or make the fastener feel tight before it is seated. Withdraw the bit occasionally to clear dust, especially in deeper holes. Blow or vacuum out the finished hole using a method that keeps dust out of your eyes and lungs. Wear eye protection, and use suitable dust protection when drilling masonry.
Use the right tool setting
Use hammer mode in concrete when the drill and bit are designed for it. Keep the drill steady and at a right angle to the surface. If the bit stops advancing, do not lean hard on the tool: withdraw it, clear the dust, and check for an obstruction. Rebar, a stone aggregate, or a worn bit can all slow progress. A masonry bit is not intended to cut through rebar; move the hole only if the fastener layout and edge distances still allow it.
In brick or block, use caution with hammer action. A hole too close to an edge, mortar joint, or brittle face can cause spalling or a split. If the brick begins to crack, stop. Switching to rotary-only mode, lowering pressure, or choosing a sounder location may prevent a bigger repair.
Common installation failures
A screw that spins without tightening often points to a hole that is too wide, damaged, or drilled in weak material. Repeatedly tightening it will not restore grip. Use a new hole at a suitable distance, following the fastener maker’s spacing and edge-distance guidance. A screw that stops partway in may be hitting packed dust, an insufficiently deep hole, or a dull bit; back it out rather than forcing it until the head or driver recess fails.
Use the correct driver bit and steady pressure when installing the screw. An impact driver can drive concrete screws, but too much force can strip the head or overdrive the fastener. Stop when the fixture is secure and the head is seated as intended. If the screw keeps binding, remove it and inspect the hole instead of treating extra torque as a fix.
What to buy for your job
For a handful of holes, buy one fresh bit in the exact specified diameter; a budget carbide bit is reasonable if the concrete is not unusually hard. For a longer run, choose a better-quality bit or an SDS-Plus bit to match your rotary hammer, and keep a spare on hand. A worn bit runs hot, drills slowly, and can leave holes that are rough or oversized. Replacing it is usually cheaper than repairing loose fasteners.
If you are unsure which diameter your screws require, read the package or the manufacturer’s instructions before drilling. The bit is a small purchase, but the fit depends on getting its size, hole depth, and dust removal right.