How To Drill Masonry
Concrete, Brick, Mortar, Quarry Tiles, Stone & Cinder Block
by Damien Andrews
Through the years, I've learned to spot a do-it-yourselfer's home. I see the tell-tale signs almost from the time I arrive at their home. Well organized garages, little details on and in the house, some tools not commonly found in households proudly displayed on a pegboard above the workbench, and so forth. They usually hire me to do something that is either too dangerous for them, or outside their scope of knowledge and/or expertise. Frequently I'll be hired by competent do-it-yourselfers just to perform some small part of a larger project, like setting the support posts for a second story balcony or taping and floating a newly remodeled garage or basement.
Recently, a gentleman who was quite obviously an experienced do-it-yourselfer hired me for a simple task: drill six holes into his brick fascia, and install anchors. His wife had some nice wrought iron hangers that she wanted installed so she could display some decorative hanging baskets and plants along the walkway to the front door. It's not the first time I've been hired to perform such a chore, but it still always surprises me when a true handyman calls on me for such a simple assignment.
After I went and assessed the job, I returned to my truck and loaded my tool bag with everything I'd need – which wasn't much – and returned to the jobsite, homeowner in tow. About the time I started to install a ¼" masonry drill bit into my ½" hammer drill, the homeowner said "I hope your drill bits are better than mine – I couldn't make any headway at all." He gestured towards a point on the brick where he'd obviously tried to drill, and failed. The hole was broadly reamed, and only about ¼" deep. I knew what the problem was, but I asked what type of drill bits he had tried anyway. I was almost embarrassed to tell him that his bits were of much higher quality than mine. Moments later I stood and (rather effortlessly) finished drilling the hole he'd started. He looked on in a combination of amazement and incredulous irritation. I put the drill down to mark the remaining holes while he closely inspected the new hole. "How the %#*%@ did you do that?" he asked. This is not the first time I've been asked this question – and colorful expletives are almost invariably included in the query.
The truth is, there is only one secret to successfully drilling masonry: a hammer drill. A hammer drill rapidly 'hammers' at the bit while it rotates. Some hammer drills have variably speeds and pressures for the hammering effect. Lower pressures work great for soft work like mortar and some stones, while the heavier pressures are required for concrete foundations and tilt walls. Today, a fella can add a light duty hammer drill to his tool bag for under $30 – and if you don't do very much masonry drilling, it will render many years of acceptable service. If you can't buy such a hammer drill locally, search the Internet for "hammer drill." You'll have more choices than you can count.
Here are a few tips for using a hammer drill and successfully drilling in masonry:
• Hammer drills come with removable, adjustable depth gauges. If the location where you're drilling allows for the gauge to be installed and used, use it. You don't want to drill too deep, and you do want to know when you're deep enough. If the gauge won't fit in the location where you're drilling, then mark the proper depth on the drill bit with a black Sharpie pen.
• Make sure that you a) seat the drill bit fully into the drill's chuck and b) completely tighten the chuck. Tighten the chuck at all three available locations on the chuck – not just one.
• You're going to need to blow the powder away from your work as you drill. This can be done with a small puffer (some hammer drills come with these), canned air or an air compressor.
• When the hole is completed, you'll need to blow out the dust that's trapped inside the hole – BEFORE you install the appropriate hardware. Again, this can be done with a small puffer, canned air or an air compressor. If you only have to blow out one or two holes, the puffer will likely work just fine. Since you really should be wearing goggles and a protective face mask to avoid the ill-effects of the noxious dust you're creating, blowing into the hole with your mouth is not recommended – strongly! If you have a number of holes to drill, especially if they are more than 1" deep, either use a compressor or buy a can of air.
• Masonry dust can be quite destructive. It is invariably abrasive, and often caustic. Be sure to thoroughly clean your drill – including thoroughly blowing out the motor through the air vents. I also brush off the drill bit before returning it to the case.
• Keep one pair of leather gloves just for drilling into masonry. There's no way to clean all the dust out of the gloves after drilling, and the dust may well be caustic to your skin. The dust is also abrasive and will 'sand' away at your hands as you work throughout the day. Better to don the special gloves for the job, and then take them off, blow them out and put them away until the next masonry drilling job comes along. Keep them with your hammer drill and you'll always be ready to go.
• If your job calls for using glue inside the hole you've drilled in the masonry, be sure to etch the inside of the hole to ensure a solid, permanent bond. The best etch is muriatic acid. Muriatic acid is a very dangerous chemical – so be sure to follow all the precautions noted on the label.