Drilling into concrete can seem daunting, but it’s often necessary for installing fixtures like railings, lamps, shelves or wiring. With the right tools and technique, you can drill clean, precise holes in concrete with ease. Here’s a step-by-step guide on how to drill into concrete successfully.
Choose the Right Drill and Bit
The key to drilling concrete is using the proper drill and drill bit. Here are the best options:
Hammer Drill
A hammer drill is a must for concrete drilling. Hammer drills combine rotation with hammering action to break through tough material. Opt for a corded electric hammer drill over a cordless one for maximum power.
Look for a drill with at least 10 amps and variable speed control. More expensive rotary hammer drills work even better but are heavier and create substantial vibration.
Masonry Drill Bit
You need a masonry or concrete drill bit, not a wood or metal bit. Masonry bits are carbide-tipped for hardness and feature a flattened tip to prevent wandering on smooth surfaces.
Match the bit diameter to the size anchor or screw you’re using. 3/8-inch and 1/2-inch bits work for many small jobs. Use lubricating oil to extend bit life.
Core Drill (For Large Holes)
For holes over 1/2-inch, use a special core drill. Core bits cut an annular ring around the hole instead of pulverizing the concrete. You’ll need a drill stand to support and guide the heavy drill. Rent an electric or hydraulic core drill if this is a one-time project.
Select the Right Location
Check for potential problems below the surface:
- Steel reinforcement – Scan with a metal detector to avoid drilling into rebar, mesh or post-tension cables. Adjust the position if needed.
- Embedded objects – Scan with an inspection camera for pipes, wires or conduit hidden in the concrete.
- Cracks – Avoid drilling near existing cracks that could propagate from the stress.
- Edges – Keep the hole at least 2 inches from the edge or any control joints.
- Load – Don’t drill within 2 inches of the bottom if the slab supports weight like vehicles.
Mark the cleared spot with masking tape or chalk. For accuracy, build a drilling template.
Prepare the Surface
Take safety precautions and make preparations for a clean hole:
- Clear the area of debris. Cover nearby objects to contain dust and fragments.
- Wear eye protection, dust mask, ear protection, gloves and close-toed shoes.
- Vacuum the surface with a shop vac to remove dirt and dust.
- For wet drilling, connect a vacuum to contain water and debris.
- To prevent bit wandering, start with a center punch or nail and hammer to create an indentation.
Drill the Hole
Follow these best practices for smooth, precise holes:
1. Start Drilling on Slow Speed
Set the clutch on the first gear and begin drilling on the lowest speed setting. Higher speeds are only for finishing the hole.
2. Apply Light Pressure
Let the hammering action of the drill do the work. Excess pressure raises dust and overheats the bit. Ease up regularly to clear debris.
3. Keep the Bit Perpendicular
Applying pressure on an angled bit will cause it to wander, making the hole elongated or uneven. Use a drill stand or brace yourself directly above for straight vertical holes.
4. Drill Partway, Back Out and Clear Debris
Pull the bit out every 1/2 inch or so to clear dust and particles. This helps the bit cut cleanly and prevents binding.
5. Finish on a Higher Speed
Once you’re over halfway through, you can step up the speed to finish drilling. Apply smooth, steady pressure until the bit breaks through.
6. Vacuum the Hole
Vacuum dust and debris from the hole. For wet drilling, vacuum water as you go and continue vacuuming at the end to leave a clean hole.
Tips for Specific Situations
Certain materials and applications call for adjustments:
Hard Aggregate Mixes
Extremely hard gravel or aggregate can dull bits quickly. Use a tungsten carbide or diamond-grit bit and lubricating oil. Drill slowly with consistent light pressure.
Underwater Applications
Look for a waterproof hammer drill with a water swivel. Start in a dry area if possible before submerging the bit. Let the tool do the work with minimal pressure.
Overhead Drilling
For drilling ceilings or inverted surfaces, choose a right-angle drill with the motor housing set at 90 degrees. Use steady pressure and brace yourself securely.
Glass Blocks
Use a specialized bit for glass blocks to avoid cracking. Drill at low speeds with a light touch. Introduce water slowly as lubrication once you establish a hole.
Tile or Brick Walls
Go slow with ceramic tiles or bricks to avoid cracking face sections. Use tape or a specialty bit guide for angled drilling.
Troubleshooting Common Issues
Here are solutions to difficulties that may arise:
Bit Skipping – The bit is likely dull, worn out or the wrong style. Try a fresh bit made for hammer drilling.
Bit Wandering – Increase downward pressure to keep the bit steady and vertical. Start with a center punch indent.
Bent Bit Shaft – Don’t force the bit if it binds. Let the hammering action work. Excess side force can bend the bit.
Hole Tapered or Cone-Shaped – Sharpen the bit if worn. Keep pressure centered and straight down.
Excess Dust – Pull the bit out more frequently to clear debris and use water or a vacuum system.
Excess Heat – Reduce drilling speed and use lighter pressure. Dip the bit in water to cool it down. The bit may be dull.
Bit Stuck in Hole – Avoid pushing too hard. Rotate the bit backward gently to try freeing it.
How to Drill Into Concrete FAQs
Get answers to common questions about drilling into concrete:
Can I Drill Into Concrete With a Normal Drill?
You need the hammering action of a hammer drill or rotary hammer to penetrate concrete. Regular drill/drivers lack the required force and are likely to burn out quickly.
What Size Hammer Drill Do I Need?
Look for a 10 amp corded hammer drill for small jobs. Larger tasks may require a 20 amp heavy duty rotary hammer. Just match the hammer drill to the bit diameter.
How Many Watts Does It Take to Drill Into Concrete?
Plan on a hammer drill with 800-1000 watts for lighter jobs, or 1800+ watts for heavy duty drilling into thick concrete with a large diameter bit.
What PSI Is Needed to Drill Into Concrete?
The actual PSI will depend on the drill, bit size and concrete hardness. Focus on using the correct hammer drill and masonry bit rather than psi requirements.
Can I Use a Normal Drill Bit for Concrete?
Absolutely not. Masonry drill bits have carbide tips and are specially designed for hammer drills. Regular drill bits will wear out instantly or snap off.
What Drill Bit for Concrete Anchor?
Match the concrete anchor diameter to the drill bit size. So a 1/4” anchor requires a 1/4” masonry bit, 3/8” for a 3/8” anchor, etc. Use a hammer drill with the anchored bit.
How Deep Can I Drill Into Concrete?
With the right hammer drill and bit, you can drill over 1 inch deep per second in concrete, so depth is unlimited. Just use care not to damage anything embedded in the concrete.
Can I Drill Through Concrete Walls?
Yes, hammer drills can bore through full thickness concrete and masonry walls. Just scan for rebar first and beware of utilities inside the wall to avoid.
Conclusion
Drilling strong, clean holes in concrete is straightforward with the proper hammer drill, masonry bits, preparation and technique. By following this guide, you’ll be able to drill concrete for anchors, fixtures and fasteners without issue.
Just remember to:
- Use a hammer drill with the appropriate power and bit size
- Select the right masonry drill bit for the job
- Check for obstacles like rebar before starting
- Start slow and increase speed gradually
- Apply smooth, light pressure, letting the tool do the work
- Keep the bit plumb and perpendicular
- Periodically back the bit out to clear debris
- Vacuum dust and water for a clean hole
With the right approach, you can drill perfect holes in concrete for your next project.