For projects around the home, it is sometimes necessary to drill into concrete. But this can be a daunting prospect because concrete is difficult to drill. Many do-it-yourselfers may decide against the project or may develop elaborate workarounds. But with the right tools and a few helpful techniques, you can drill into concrete successfully and with less effort than you may imagine.
The Basics of Drilling Into Concrete
Drilling into concrete is difficult because concrete is dense, hard, and has embedded aggregate stones that can be obstacles to the drill bit. Drilling can quickly dull drill bits. When the bit encounters aggregate, the bit drags even more. The preferred tool for drilling into concrete is a hammer drill.
Drill Concrete With a Hammer Drill
A hammer drill is different from an ordinary rotary drill. Like a rotary drill, the hammer drill rotates. Unlike a rotary drill, it hammers while it rotates. Hammering helps to pulverize the concrete, while the rotation forms the hole.
If you anticipate drilling many holes in concrete, it may be beneficial to purchase a hammer drill. Hammer drills are available in both corded and cordless versions. Most hammer drills have two modes: simultaneous hammer/drill mode and drill-only mode.
Drill Concrete With a Rotary Drill
It is possible to drill into concrete with an ordinary rotary drill. Rotary drills take longer to drill into concrete than hammer drills and more physical effort is required. Excessive heat build-up can break the drill bit.
One way to speed up the process and to avoid breaking the drill bit is to keep the bit cool. With cordless drills, you can run a slow, steady stream of water across the surface. With corded drills, holding a shop vacuum nozzle close to the drilling surface both cools the bit and keeps the hole free of debris.
Where You'll Need to Drill Into Concrete
Projects and remodels around the home that may require you to drill into concrete include:
- Installing shelves or hanging heavy mirrors on concrete block walls
- Hammering a concrete nail into concrete
- Installing metal anchors in concrete slabs when building wood-frame walls
- Drilling pilot holes for masonry screws
- Installing toilet closet flanges on concrete slabs
- Attaching footers for patios, pergolas, and other outdoor structures
Always use safety gear when drilling into concrete: hearing protection, eye protection, a dust mask or respirator, heavy gloves, boots, and long sleeves.
Equipment / Tools
- Hammer drill
- Corded or cordless rotary drill
- Carbide-tipped masonry bits
- Center punch or nail set
- Shop vacuum with a HEPA filter and bag
- Safety gear
Create a Drilling Point
It can be difficult to begin a hole on smooth concrete as the bit has a tendency to slip from the desired spot. Lightly tap a center punch or nail set with a hammer to create a tiny indent on the concrete.
Install the Depth Stop
Adjust the depth stop on the side of your drill to the depth of the intended hole.
Alternatively, you can measure out the depth of the hole on the drill bit with a tape measure. Then, wrap tape above that section of the bit to indicate where you should stop drilling.
If you are looking at your drill bits and don't know if they are masonry bits, there is an easy way to tell. Masonry bits have a paddle-shaped end to help dig out the waste material.
Add the Drill Bit to the Drill
Hammer drills often use a chuck-key system of securing the bit in the drill. Open the chuck jaws with the key, insert the bit, then turn the chuck key clockwise to tighten the bit in place.
If you are using a rotary drill, it may have a keyless chuck. Open the chuck by hand by turning it counter-clockwise (as if opening a jar). Insert the bit. Then turn clockwise to tighten the bit.
Set up the Shop Vacuum
Place the nozzle of the shop vacuum within 2 inches of the drill point. If you are drilling into a concrete floor or slab, you can usually kneel lightly on the nozzle to hold it in place. Or you may wish to place a heavy object over the nozzle to stabilize it. Turn on the vacuum.
Begin Drilling Slowly
Squeeze the trigger gently to begin rotating the bit at a slow speed. At this point, only press lightly on the drill; let the drill do most of the work.
When using a rotary drill, it helps to begin with a bit smaller than your intended hole—about one-third the size. Progressively work up to the correct size. You may need to use two or three intervening bits until you reach your intended size.
Take Frequent Breaks
When using a hammer drill to drill into concrete, it is beneficial though not critical to take breaks. When using a rotary drill, it is necessary. Breaks allow the bit to cool down and they give you a chance to further vacuum out debris from the hole. Check the condition of the bit during the break to make sure that it is not broken or overly dull.
Tips For Drilling Concrete
- Since drilling into concrete is laborious, you'll want to drill only as far as you need. Limit the depth of the hole by using the depth stop rod included on most hammer drills and some rotary drills.
- Apply less pressure when drilling into lighter weight concrete or brick to avoid cracking it.
- Using an auxiliary handle on the drill helps you to apply more pressure to the drill while increasing safety. If your drill has an auxiliary handle, install it for this project.