Can I screw straight into brick or concrete without a wall plug?

The plug-and-screw combination exists because a normal thread cannot cut masonry. A concrete screw — sold under several trade names and sometimes called a masonry screw or a frame screw — is made of much harder steel with a widely spaced, sharply profiled thread that does exactly that. It removes the plug, and with it the two commonest causes of failure: a plug that spins and a plug that has been hammered in damaged.

What you'll need

• Concrete screws of the stated diameter and length
• A masonry bit of exactly the diameter the screw specifies
• A hammer drill or SDS
• Dust blower or vacuum
• An impact driver or a socket, depending on the head (optional)

Step by step

1. Check the substrate is suitable.Concrete screws are at their best in dense concrete, dense block and sound brick. They are poor in aerated block, in soft crumbly Victorian brick and in perforated brick, all of which need a different approach.
2. Drill exactly the diameter the screw calls for.This is far less forgiving than a plug. The thread has to have material to cut into. A hole a millimetre oversize gives a screw that spins with no grip at all.
3. Drill deeper than the screw will go.Allow at least 10mm of extra depth. The thread pushes dust ahead of it and a screw that bottoms out will shear or simply stop turning while still proud.
4. Clear the dust properly.Blow and vacuum. Cuttings packed in the flutes of the hole are what stops a concrete screw reaching depth.
5. Drive it with steady controlled torque.A socket on a driver is ideal for hex-head types; a Torx or Pozidriv countersunk type drives with a bit. Slow down as the head approaches — the last turn is where over-torque snaps them.
6. Stop as soon as the head seats.There is no plug to compress, so nothing gives you warning. Turning on after the head is home simply strips the thread it just cut, and the hole is then useless.
7. Treat removal and reuse with caution.One removal and one re-drive into the same hole is usually fine. Repeated cycles wear the thread in the masonry away and the screw ends up loose.

Tips

• Concrete screws are the standard fixing for through-fixing battens, frames and metalwork where a plug's expansion force would be a problem — for instance close to the edge of a slab or a brick.
• A countersunk concrete screw with a Torx drive is much less likely to round out than a hex head with a worn socket.
• They are removable, which makes them excellent for anything temporary — a fence prop, a formwork batten, a shuttering fixing.

Common mistakes

• Using a bit one size up because the screw is stiff — The stiffness is the thread cutting, which is the entire mechanism. Oversizing the hole eliminates it and the screw will never hold.
• Using concrete screws in aerated block — The screw cuts a thread in material with almost no compressive strength, and it strips under very little load. Aerated block needs its own purpose-made fixings.

If it doesn't work

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