How to Drill Into Concrete, A Step-by-step Guide

You've got a home project lined up—hanging a heavy mirror, perhaps, or installing new garage shelves. The perfect spot is chosen, but then you realise it's concrete. Suddenly, you hit a wall and ask yourself, “How do I even drill into concrete?”

Many people encounter the challenge of drilling into concrete, and it often seems intimidating. However, with the right tools and techniques, it’s a skill anyone can master. 

In this article, we'll discuss each step, from selecting the correct drill bit for concrete to understanding how to drill through walls and slabs safely. Whether you’re doing a simple DIY project or working on a more complex construction task, we’ll cover it all.

Drilling into concrete presents unique challenges compared to working with wood or metal. Unlike these materials, concrete is a composite consisting of cement, sand, and aggregate (small stones). This heterogeneous composition makes drilling concrete significantly more demanding. 

Also, the hard aggregate resists standard drill bits, requiring specialised tools and techniques. Using inappropriate drill bits may quickly wear down the tool, leading to inefficient drilling holes in concrete and potential damage to both the drill and the surface. 

Therefore, understanding the composition of concrete is crucial for effective drilling into concrete. Using the appropriate tools, like a hammer drill and a carbide-tipped drill bit for concrete, along with proper techniques, is essential to penetrate this tough material without causing cracks or excessive wear. This way, you can ensure clean, precise holes and prolong the life of your equipment when drilling through concrete.

Once you have the necessary tools and equipment, follow these step-by-step instructions to drill into concrete effectively.

Marking and Preparing the Drilling Spot

Accurate marking is the first step, and you’ll need to use a pencil or chalk to clearly mark the exact spot where you need to drill. Remember to be precise to avoid mistakes and ensure proper alignment.

If you’re drilling into a concrete wall, use a stud finder or pipe detector to check for embedded pipes or electrical wires. This prevents accidental damage to utilities.

To keep the drill bit from slipping, especially on smooth surfaces, apply a piece of masking tape over the marked spot. This way, you can get a better grip on the drill bit, ensuring it starts drilling exactly where intended.

Drilling the Pilot Hole

Starting with a pilot hole is crucial, especially when drilling larger holes into concrete surfaces. For this step, you’ll need to use a smaller masonry drill bit than the final size to reduce stress on the drill and prevent the concrete from cracking.

Then, set your drill to the hammer drill setting to effectively penetrate the hard concrete surface. Instead of constant drilling, use short bursts because this helps to keep the drill bit from overheating and reduces the risk of it breaking. Also, short bursts allow you to clear debris from the hole more frequently, which improves drilling efficiency.

Drilling to the Desired Depth

For proper anchor placement, you need to ensure accurate depth control. Use a depth stop on your drill or wrap masking tape around the drill bit at the desired depth. This way, you can have a visual guide and prevent yourself from drilling too deep into the concrete.

During drilling, pull the drill bit out every few seconds to clear debris from the hole. Doing so will keep the bit from getting stuck and reduce friction, which can cause overheating. Clearing debris also ensures that the hole is being drilled evenly and accurately.

Clearing the Hole and Checking for Accuracy

After drilling, use a vacuum, compressed air, or a brush to thoroughly clear out concrete dust and debris from the hole to ensure proper anchor or wall plug placement. If needed, insert a wall plug or anchor into the hole.

While at it, check that the hole is deep enough and properly aligned before inserting any fasteners to ensure a secure and stable hold. Additionally, verify that the hole's diameter matches the anchor size. Remember, ensuring the hole is clean and accurate is vital for the longevity and stability of your installation.

Even with the right techniques, you might encounter some common challenges when drilling into concrete. Here’s how to address them:

• Drill Bit Not Making Progress: If the drill bit seems to be spinning without penetrating the concrete, check if you’re using one with a carbide or tungsten carbide tip. Also, make sure that the bit is sharp. Otherwise, you’ll struggle to drill into the concrete slab. Once you’ve ensured that you have the right drill bit, apply consistent, firm pressure to the drill. Also, make sure the hammer drill function is engaged. And if the concrete is extremely hard, consider using a rotary hammer for increased power.
• Bit Gets Stuck in the Hole: If the drill bit becomes lodged in the concrete, stop drilling immediately. Switch the drill to reverse and try to slowly back the bit out. If it’s still stuck, gently wiggle the drill while pulling. Additionally, clear debris from the hole frequently during drilling to prevent this issue. Avoid forcing the bit, as this can cause it to break.
• Hitting Rebar Inside Concrete: If the drill bit hits the metal rebar, preventing further progress, stop drilling. Try to reposition the hole slightly. If repositioning isn't possible, use a metal-cutting drill bit to cut through the rebar. Also, be prepared for increased resistance and potential damage to the bit. Finally, consider consulting a professional if you frequently encounter rebar, as it might indicate structural concerns.
• Excessive Dust Buildup: If a large amount of dust is produced, creating a mess and potential health hazard, use a vacuum cleaner with a dust extraction attachment to collect dust as you drill. Remember to work in a well-ventilated area or wear a dust mask and clear debris from the hole frequently. Consider using a wet drilling technique for professional applications, where water is used to suppress dust.

Different concrete surfaces present unique drilling challenges and require specific approaches, and here are some tips on how to handle them:

Drilling Into Concrete Slabs and Floors

When drilling into concrete slabs or floors, it’s crucial to maintain stability. So, ensure the surface is clean and level, and use a rotary hammer for thicker slabs, as it provides the necessary power.

To prevent the drill bit from wandering, start with a pilot hole. Also, pay close attention to the depth of the hole, especially if there are embedded utilities or underfloor heating. Regularly clear debris to prevent the bit from binding. For large-diameter holes, consider using a core drill bit.

Drilling Into Concrete Walls

Drilling into concrete walls requires extra caution due to potential embedded utilities. Always use a stud finder or pipe detector to locate pipes and wires before drilling. Additionally, mark the drilling spot accurately to avoid errors and use masking tape to prevent the drill bit from slipping.

Start with a hammer drill and apply consistent pressure. While at it, be mindful of the wall's thickness to prevent drilling too deep. Regularly remove the dust to maintain visibility and prevent overheating.

Drilling Through Concrete Completely

Drilling completely through concrete requires precision and power. Also, use a rotary hammer with a long, high-quality masonry drill bit and mark both sides of the concrete to ensure proper alignment.

Once you have a pilot hole, gradually increase the drill bit size. Apply consistent pressure, maintain a steady drilling speed, and regularly clear debris to prevent the bit from getting stuck. Additionally, be prepared for increased resistance and potential vibration.

Selecting the appropriate drill bit is crucial for efficient and effective concrete drilling. Here's a breakdown of common types:

• Standard Masonry Bits: These are best suited for drilling small holes in light concrete or masonry, and they are typically made of hardened steel with a carbide tip. What’s more, they are ideal for basic DIY tasks, such as hanging light fixtures or drilling into softer concrete blocks. However, they may struggle with harder aggregates or reinforced concrete.
• Carbide-Tipped Masonry Bits: These bits are designed for drilling into reinforced concrete and harder masonry materials. That’s because the carbide tip is significantly more durable and can withstand the abrasive nature of concrete and rebar. They are essential for projects involving structural concrete, where standard masonry bits would quickly wear down.
• Diamond-Tipped Drill Bits: For drilling through extremely hard surfaces, such as granite, tile, or very dense concrete, diamond-tipped drill bits are the optimal choice. The diamond coating provides exceptional hardness and durability, allowing for clean and precise holes. Also, these bits are often used in professional applications where precision and longevity are paramount.
• Core Drill Bits: Core drill bits are used for drilling large-diameter holes in concrete, typically for pipes, ducts, or electrical conduits. These bits create a cylindrical hole by cutting around the perimeter, leaving a core of concrete that can be removed. They are commonly used in professional construction and renovation projects, where large, clean holes are required.

Safety should always be a priority when drilling into concrete, and we recommend following these essential tips:

• Always wear safety glasses and gloves to protect against flying debris. Concrete drilling produces small, sharp particles that can cause eye and skin injuries.
• Use ear protection, as hammer drills can be very loud. Prolonged exposure to loud noises can lead to hearing damage. Earplugs or earmuffs will help mitigate this risk.
• Avoid inhaling dust, work in a well-ventilated area, and use a dust extraction system. Concrete dust contains silica, which can cause respiratory problems. So, open windows and doors or use a vacuum with a HEPA filter to minimise dust inhalation.
• Keep the drill stable to prevent bit breakage and uneven holes. Remember, an unstable drill can cause the bit to snap or create angled holes, leading to project failures and potential injury.