It can be difficult to successfully fix items like shelves and cupboards to hollow walls (also referred to as stud partitions, stud walls and dry wall). The thickness and crumbly nature of the plasterboard used in the wall’s construction doesn’t support much weight, so alternatives to the normal plastic wall plug and screw are often needed.
One kind of fixing that can be used usually without fear of it coming loose is a metal wall anchor specifically made for hollow walls. To help fit these, it’s best to use a dedicated device – a metal anchor expansion tool, also referred to as a setting tool.
What is a hollow wall?
A hollow wall (also called a partition or stud wall) is one made using a timber (and sometimes steel) frame covered with plasterboard sheeting (known as drywall in the USA) with a hollow cavity.
They are used as internal walls to partition rooms, as a quicker, cheaper alternative to a solid brick or block wall. Hollow walls also allow insulation and services such as pipes and electrical cable to be fitted inside their cavity, out of sight.
What is a metal hollow wall anchor?
There are many types of fixings used on hollow walls. Each has advantages and disadvantages for different applications. The metal hollow wall anchors used with expansion or setting tools are also known as cavity fixings or Molly anchors.
Metal hollow wall anchors comprise an inner screw with an outer shell that features a flange with anti-rotation barbs at one end, an integral nut at the other and collapsing legs in the middle.
When fitted to plasterboard stud walls, the screw of a metal hollow wall anchor can be removed and then screwed back in to fix or hang objects on the wall.
Why use an expansion or setting tool?
Many people think you do not need to use a setting tool to fix hollow wall anchors in plasterboard. However, if you try to fix these anchors in plasterboard using just a screwdriver, there is a risk of the anti-rotation barbs turning with the screwdriver once the collapsing legs on the anchor have folded back against the plasterboard.
This results in the barbs digging out a large hole in the plasterboard. As the collapsing legs of the hollow wall anchor have already been bent back, removing the anchor will only create a larger hole, so the often the only solution is to knock it through into the wall cavity and fill the hole left behind.
A setting tool pulls the screw of the hollow wall anchor back without turning it. This means the legs are collapsed without the outer shell of the anchor being turned, so the anti-rotation barbs press into the plasterboard but do not turn and so can’t create a large hole in the plasterboard.
