Expansion anchor

An expansion anchor is a part that is inserted into a drilled hole and which, as the screw or the nut is tightened, opens out and holds by pressing against the sides of the hole.

There are plastic ones, known as wall plugs, for light loads, and metal ones for heavier loads. For a security grille the sensible choice is a metal anchor of the right size, never a plastic wall plug of the kind used to hang a picture.

It works very well in solid materials, such as concrete or solid brick, which can take the pressure. In hollow brick or block, on the other hand, it can break the inner wall of the cavity and end up loose. There, a chemical anchor is usually better.

A tip: make sure the head of the screw cannot be reached from the outside, or cannot be undone with an ordinary tool. More information on our security grilles page.