Screw types and their uses (page 1)

Screws can provide a strong, neat fixing to walls, man-made board, timber and even concrete, provided you choose the right fixing for the job.

Screws pull together the surfaces to be joined as the thread on the shank is rotated. The fixing is very strong and can be taken apart easily. Choose brass or plated (stainless-steel) for outdoor work. Black lacquered versions are also sold, to match black hinges and latches.

The screw length should be about three times the thickness of the timber it is fixing in place. The thicker the screw, the greater the grip.

Screw sizes

Screws are sold according to length and gauge (shank diameter). The length is defined as the distance between the tip of the screw and the surface of the wood. The greater gauge number, the thicker the screw, with 20 being the highest.

Types of screw

Countersunk Slotted

Traditional screw with a long shank. Still widely used and most suitable for traditional pieces of furniture and restoration work.

Countersunk Crosshead

Probably the most popular type of screw because the cross-shaped slot tends to prevent the screwdriver slipping.

Roundhead

Used mostly for fixing items without countersink holes. The top is rounded and sits out from the surface.

Raised head

This is a sort of hybrid from the last two. The top is slightly rounded and the base countersunk. It is most commonly used for fitting ironmongery, such as door handles.

Mirror screw

As the name implies, this is most commonly used for fixing mirrors. It has a countersunk slotted screw, which is fixed first. A dome shaped chrome cover is then fastened into the top of the screw. When used for fixing mirrors or other fragile objects, a small rubber insert is set in the screw hole of the item to prevent the metal of the screw damaging it.

Continued...

• Screwing wood
• Nails
• Wall fixings