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Last edited 21 Jun 2022

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Wall plug

1 Outline
2 Composition
3 Threaded plugs
4 Nailable plugs
5 Related articles on Designing Buildings

[edit] Outline

A wall plug (commonly called a rawl plug) is used to ensure screws driven into masonry walls provide a secure fixing. Without them, screws would not grip into masonry and would not provide adequate compressive force to ensure a secure, permanent fixing.

Installation usually involves ensuring first that the correct size plug is paired with the screw. As the screw must fit inside the plug, the hole to be drilled will be larger than it would be for the screw. The plug is inserted into the drilled hole and the screw is driven into the plug. As the screw penetrates the plug, it gradually forces the plug sides to expand outward, applying a compressive force against the masonry (which can be brick, block, concrete or plasterboard). The screw is tightened until it has fully penetrated into the plug, at which point it cannot be tightened any more.

Sometimes the screw turns indefinitely without tightening. This usually means the wrong size of plug has been used or the hole drilled is too big for the plug. One possible remedy is to take out the screw and take up the slack with matchsticks, filler, plaster pads or other material that will reduce the size of the hole, or to use a larger wall plug.

[edit] Composition

Typically, wall plugs are made of medium-duty, moulded plastic that can be used with a range of standard screws, from No 4 to No 14 sizes. They are usually tapered and profiled to increase their grip; they come in a range of profiles, colours and sizes.

Wall plugs are also supplied as extruded plastic – often straight tubes of 150mm-200mm lengths that must be cut to size according to requirements. But because they have straight sides, they must be cut shorter than the depth of the hole.

[edit] Threaded plugs

For screwing into less dense, friable walls, such as aerated concrete blocks, plugs are available with a thread on the outside; once screwed into the wall they form the socket for the screw and in all respects behave like ordinary wall plugs.

[edit] Nailable plugs

Nailable plugs come in various shapes and sizes and can be used with nails in masonry and plasterboard. They are useful when many fixing points must be made quickly. Both nail and plug are simply hammered-in as one fixing. Typical applications include fixing skirting boards, wall linings, battens and frames.