Drilling Into Brick Safely: The Right Bit, Speed and Technique

Drilling into brick is straightforward once you accept that brick is not wood and will punish you for treating it like wood. You need a masonry bit, hammer action on anything harder than soft red brick, slow steady pressure, and a plan for where the hole actually goes. Get those four right and a hole takes twenty seconds instead of twenty minutes of smoke and frustration.

Check what you are actually drilling into first

People say "brick" when they often mean the mortar joint, a concrete lintel, or a modern lightweight block behind a brick skin. It matters, because each one behaves differently under a bit.

• Facing brick is hard, dense and fires off orange dust. It holds a fixing well.
• Mortar joints are much softer and easier to drill, but they hold far less weight. Fine for a hose reel, not for a TV bracket.
• Concrete lintels sit above windows and doors and are usually brutally hard. Expect a slower going and reinforcing bar you must not cut.
• Aerated blocks (the pale, chalky sort) drill like cheese and need special fixings, not standard plugs.

Scratch the surface with a screwdriver tip in a spot that will be hidden. If it crumbles easily you are in mortar or block; if it barely marks, it is brick or concrete.

Safety before the drill comes out

The genuinely dangerous part of drilling brick is not the drilling. It is what lives behind it. Cables run vertically and horizontally from sockets and switches, and pipework often runs in odd routes in older houses. Run a cable and pipe detector over the area, check it in more than one direction, and stay well clear of anything directly above or below a socket, switch or light fitting.

Then sort the basics: safety glasses because brick dust flies straight back at your face, a dust mask because silica dust is not something to breathe casually, and gloves if you are working overhead. If you are on a ladder, get the ladder positioned properly first rather than reaching sideways with a running drill in your hand.

Pick the right bit

A masonry bit has a carbide tip brazed to the end, wider than the flutes, and it looks blunt compared with a wood or metal bit. That bluntness is the point. It smashes and grinds its way through rather than cutting. A standard HSS twist bit will glaze over and go dull within seconds in brick, so do not try it.

Match the bit diameter to the plug, not to the screw. A 6mm brown plug takes a 6mm bit, a 5mm red plug takes a 5mm bit. Drilling oversize is the single most common reason a plug spins uselessly in the hole. Also check the bit is long enough: it needs to reach plug depth plus roughly 10mm of spare so debris has somewhere to sit.

If you have an SDS drill, use SDS masonry bits. They hit harder and clear dust better, and they make short work of dense brick and concrete. For a standard combi drill, a round or hex shank masonry bit in the chuck is fine for most household jobs.

Set the drill up correctly

Three settings matter, and getting them wrong is why so many holes go badly.

1. Mode: switch to hammer, shown by the little hammer symbol. On a combi drill this is a separate collar from the clutch ring.
2. Clutch: if your drill has a drill or hammer icon on the clutch collar, select that rather than a number. The clutch should be out of the way so it does not slip mid hole.
3. Gear: use low gear (1) for larger holes where you want torque, and high gear (2) for small diameter holes in ordinary brick. Hammer action does the work, not raw speed.

Make sure the bit is properly seated and tight in the chuck. Masonry drilling generates a lot of vibration, and a half tightened chuck lets the bit creep out and wobble.

The drilling technique itself

Mark your spot and, if you can, aim for the middle of a brick rather than a joint or the very edge. Drilling within about 25mm of a brick edge risks blowing out a corner.

Start without hammer action for the first two or three seconds, at low speed, just to bite a small crater so the tip cannot skate. Then switch hammer on and let the drill settle into a rhythm. Hold it square to the wall, with two hands if the drill has a side handle, and apply firm consistent pressure. Not body weight, just enough that the bit is always cutting.

Back the bit out an inch or two every few seconds. This clears dust from the flutes, and packed dust is the reason a hole that started well suddenly stops progressing. If the bit stops advancing and the tip is going shiny or blue, stop. You are either on something hard like a lintel or a stone, or the bit is finished.

Wrap a strip of tape around the bit at your target depth so you know exactly when to stop. It saves punching through a single skin wall or into a cavity you did not intend to open.

Finishing the hole and fitting the plug

Blow or vacuum the dust out before the plug goes in. A hole full of dust means the plug bottoms out early and never expands properly. A drinking straw works well for blowing it out from a safe angle, but keep your eyes clear.

The plug should push in with light taps from a hammer and sit flush with the surface. If it slides in loosely, the hole is oversize: go up one plug size or move over and start again. Drive the screw in with a driver rather than at full speed on a drill, and stop as soon as it feels tight. Overdriving strips the plug and you lose all the grip you just made.