How do I fix kitchen wall units to a plasterboard wall?

The hanging rail method, why unit brackets need timber behind them, and how to deal with studs that do not line up with the unit positions.

Difficulty: intermediate
Time: 2 hr
Read: 3 min
Safety: warning

Short answer

Fix a continuous timber hanging batten into every stud along the run, then mount the units to that with their own hanging brackets. That way the unit positions no longer have to match the stud positions, the load spreads along the wall, and each unit's brackets bear on solid timber.

Wall units are hung on cabinet hanging brackets that adjust in two directions, which is what lets a run of units line up. Those brackets pull hard on a small area of wall, and the load is far greater than people expect once the units are full. The standard trade answer on a stud wall is not a stronger anchor — it is a timber rail across the studs.

Safety

Loaded wall units are among the heaviest things people hang on a domestic wall — crockery, tins and glassware add up fast — and they sit directly above a worktop where somebody stands and works. A unit coming down is a serious injury. Fix into timber, use the load-rated hanging brackets the units came with, and never mount a run on cavity fixings alone.

What you'll need

Stud detector and, for steel framing, a magnet
Cable and pipe detector
Timber batten or 18mm plywood for the hanging rail
Long wood screws
A long level, and a laser level if you have one
Help to lift the units

Step by step

Set the height line first and get it dead level.Wall units are set out from a single continuous line, usually referenced from the worktop height and the tall units if there are any. Mark it right along the run with a laser or a long level — every subsequent error compounds from this line.
Find and mark every stud.Detector, tapping, or a magnet on a steel-framed wall. Mark them above the line so the marks stay visible while you work.
Check for services along the whole run.Kitchen walls carry cables to sockets, cooker points, extractor and lighting, and sometimes pipework. Check every position, and be especially careful directly above sockets.
Fix a continuous hanging rail into every stud.A timber batten or a strip of 18mm plywood, run behind the whole line of units, screwed into each stud with long screws — two per stud where the batten depth allows. This is the load-carrying element of the whole installation.
Check the rail is level and true before hanging anything.Put the level on the rail itself. Correcting the rail now takes two minutes; correcting a hung run of units takes an afternoon.
Mount the units to the rail with their own hanging brackets.The brackets that came with the units are rated for them and adjust vertically and horizontally, which is how you get the doors to line up. Screw them into the batten, not through it into board.
Hang the units and connect them to each other.Units are joined side to side with connecting bolts, which makes the run behave as one stiff assembly rather than several independent boxes. Do this before final levelling.
Adjust, then check the whole run.Adjust the brackets until the tops line up and the doors have even gaps. Then push and pull on the units — anything that moves is a fixing that has not reached timber.
Load them gradually and re-check.Put weight in and check again after a day. Any settling shows up now, before there is glassware on the top shelf.

Tips

If the wall is being built or re-boarded, ask for full-height plywood behind the whole unit run rather than noggins. It is cheap at that stage and removes every future fixing problem including the extractor and the shelves.
Corner units and tall end units carry disproportionate load and are often the ones with the least stud behind them. Check those positions specifically.
The batten does not have to be visible — it can sit entirely behind the units, or be scribed and painted where it shows below them.

Common mistakes

Hanging units on cavity fixings because they felt solid empty — The load roughly triples once the units are full, and the leverage of a deep unit multiplies the pull-out force on the top fixings. Empty is not a test.
Setting out from the ceiling or the worktop rather than a level line — Neither is reliably level. The run then follows the error, and the doors show it clearly along the whole kitchen.