Drilling through concrete isn’t as scary as it sounds, as long as you have the right tools and follow the correct safety precautions! Here’s a step-by-step guide to drilling into concrete.
Drilling concrete is much easier with a hammer drill (or rotary hammer drill for larger jobs), as they fracture the concrete using quick, rapid hammer-like movements, and the drill then scoops out the broken material. Regular rotary drills are designed to shave the material away, which works well for metal and wood, but not so much for concrete, resulting in a slower and more difficult process.
For this reason, if you’re drilling anything more than a few small holes in cosmetic (non-structural) concrete, renting or even purchasing a hammer drill is a worthwhile investment. Try to choose a drill with at least 7 to 10 amps, and ideally a speed setting, depth stop, comfortable grip, and a second handle for your other hand to add stability.
Before commencing with your drilling, make sure to read the user manual and familiarise yourself with the features of your drill, to ensure that you’re comfortable with using it.
You’ll need a high quality masonry drill bit to insert into your hammer drill, specifically a carbide-tipped bit intended for hammer drills. These are designed to withstand the force of hammering, and are ideal for drilling dense concrete. When choosing your drill bit, ensure that the flutes of the bit are at least as long as the hole you plan to drill, as this will enable you to remove any dust from the hole.
If you’re using a rotary hammer drill, you’ll need a specialty drill bit (SDS or SDS-MAX for holes up to 16mm in diameter, or Spline-Shank for larger holes). Additionally, if you’re drilling through reinforced concrete and need to drill deeper than the steel rebar, you’ll need to switch to a special rebar-cutting bit once the drill hits metal.
A masonry nail is a helpful tool for breaking through any tough spots or obstructions that you might find when drilling through your concrete.
You’ll need to remove any dust from the hole once you’ve finished drilling, and using a can of compressed air is an effective way of doing this.
As with any construction or home renovation project, all safety precautions should be adhered to. This includes wearing personal protective equipment such as safety goggles, hearing protection, and heavy gloves. A respirator is recommended for larger projects that may create more dust. You may also wish to cover any nearby windows or doors with plywood, and move any vehicles out of the area.
Setting the drill depth
Some drills have a setting that lets you control the depth – to learn how to use this, check the user manual. If your drill doesn’t have an inbuilt drill depth setting, you can measure and mark the required depth on your drill bit manually, using a piece of masking tape.
Holding the drill
You can hold the drill the same way you’d hold a gun – with one hand, and your index finger on the “trigger” which turns the drill on and off. If the drill has a second handle, you can hold this with your other hand – otherwise, place your other hand at the back of the drill for added stability, since you may experience some kickback or recoil.
Marking the spot
Before you start drilling, mark the spot you’re needing to drill by making a small cross on the surface with a soft pencil.
1. Drill a pilot hole
First, drill a small pilot hole (only several millimetres in depth to help guide your drill. Simply place your drill on the mark you created, and use either a low speed setting or short bursts to create a shallow hole. You may wish to use a smaller drill bit for the pilot hole, for added stability.
2. Increase the power
Now, it’s time to turn on the hammer function of your drill. Place the drill in the pilot hole and keep it perpendicular to the concrete surface, then start drilling with firm pressure (without forcing it) to push the drill forward. You can gradually increase the drill speed and pressure as necessary, but take care to make sure the drill remains stable.
3. Remove the drill periodically
Approximately every fifteen seconds, pull the drill out of the hole slightly and then push it back in to encourage dust out of the hole. You should also stop the drill every few minutes and remove it completely from the hole to let it cool and prevent overheating.
4. Break through obstructions
If you encounter any especially hard pieces of concrete or other obstructions, you can insert a masonry nail into the hole and hammer it to break these down, before recommencing your drilling. Make sure not to insert the masonry nail in too deep for you to easily remove!
If you see any sparks or metal, you’ve likely hit rebar, and should instead use a rebar-cutting drill bit to move through this.
5. Remove any dust
Use a can of compressed air to blow out the dust from the hole once you’ve finished drilling, and then vacuum this up. Make sure to leave your goggles and mask on during this process to protect yourself from debris, and prevent inhaling any hazardous dust.
An alternative method is using a damp cotton swab to wipe the dust out of the hole.