Metal shelving units need to be kept rigid at all times. They are different to shelving units made from wood because any joint movement at all in metal units works the bolts loose.

With heavyweight metal shelving systems, it is best to either brace them on three sides as a free-standing unit or you could secure them to a wall. Two braces are not enough to make the system completely safe. For instance, if a unit were braced at the rear and right side, it would still enable the left side to twist, albeit only slightly. However, even a slight amount of movement would be enough to loosen the bolts holding the joints together and possibly cause an accident.

Lightweight steel units will also need bracing on three sides. The light systems usually have quite shallow shelves. This makes them too easy to topple over and cause damage or injury. Your best bet is to secure them firmly to a wall as well as bracing them. Another option is to fix them to more shelving units, which will give them greater stability. This, of course, depends on the amount of floor space available to you, since lightweight units tend to be used in the garage or garden shed.

Bracing a unit is quite simple. Basically, all you need to do is attach a piece of wood or metal diagonally across each of the three sides. This will create triangular shapes which will make sure that the shelving unit is completely rigid.