The safest way to hang a shelf on plasterboard is to fix into the timber or metal studs behind the board. Where a stud is not in the right place, a proper cavity fixing rated for the load is the next best option. Ordinary plastic wall plugs are designed for solid masonry and will pull out of plasterboard under weight. Before drilling anything, check for hidden cables and pipes.
First, work out what the wall is
Knock along the wall. A hollow sound with occasional solid spots suggests plasterboard on studs. A uniformly solid sound suggests plaster on brick or block, which takes ordinary plugs and screws. Many homes have both: solid external walls and stud partitions between rooms, and older properties can have lath and plaster, which behaves differently again.
Plasterboard dabbed directly onto a masonry wall is a common trap. It sounds hollow in places but has brick close behind, so the fixing has to pass through the board and grip the masonry.
Finding the studs
Studs are usually spaced at regular intervals, and a stud detector makes finding them straightforward. Screw heads in the plasterboard, the edges of sockets and switches, and the corners of the room give clues too. Fixing a shelf bracket into a stud gives by far the strongest result, and for long shelves the bracket spacing can often be planned around the stud positions.
Choosing the right cavity fixing
When a bracket has to land between studs, the fixing does the work, and fixings are not all equal.
- Plastic plugs: for solid walls only, not plasterboard
- Self drill plasterboard fixings: light loads such as small frames
- Spring and gravity toggles: medium loads, with a larger hole
- Metal cavity anchors that expand behind the board: heavier shelves
- Timber noggins fitted inside the wall: the strongest option for heavy items
Weight matters more than people think
A shelf loaded with books is far heavier than it looks, and the leverage of a deep shelf multiplies the pull on the top screws. The fixing packet states the load it is rated for, and it is worth staying well inside it. For kitchen cupboards, televisions, heavy mirrors and floating shelves, which put all their load through concealed fixings, a stud or a noggin is the safe choice.
Cables and pipes behind the wall
Electric cables commonly run vertically and horizontally from sockets and switches, and pipes can be anywhere near radiators, kitchens and bathrooms. A detector helps, but it is not infallible. Avoid drilling directly above, below or beside sockets and switches, and take extra care on walls backing onto a kitchen or bathroom.
Getting a shelf level and in line
A shelf can be securely fixed and still look wrong. Mark the height with a spirit level rather than measuring down from the ceiling, because ceilings and floors are rarely true, especially in older houses. On a run of shelves, set out every bracket position before drilling the first hole, so spacing and heights are consistent along the wall.
Drill pilot holes carefully, and if the drill suddenly breaks through into a void, stop and reassess the fixing rather than forcing a plug into the hole. Finally, fill and touch up any stray marks so the finished wall looks as tidy as the shelf.
When to hand the job over
Floating shelves, wall hung units and long runs of shelving where the levels must line up perfectly are where experience pays off. So is any wall where you cannot work out what is behind it. Shelving and flat pack assembly are typical small jobs, and several can be grouped into one visit so the fixings, levels and making good are done together.