Even when metal storage racks have been braced and stabilised, the bolts will eventually loosen. In the first place, the bolts should always be tightened with a socket or a spanner to get enough torque. The fixing bolts, if tightened with pliers, will not give enough rigidity. They will loosen, no matter what, but a lot more slowly.

An all round tightening should only be needed approximately every one to two years or so. If this is overlooked, the shelves will become unstable and unsafe. Storage racks that do not have adequate bracing, in other words on three sides, may become loose very quickly. It is entirely possible that a rack without proper bracing will loosen to the point where it is about to collapse in less than a week.

With wooden shelving units, two by two inch uprights will give a racking system suitable for the usual household loads, if they have been well braced and jointed. For a shelf to be well jointed it needs metal reinforced joints, large corner braces, for example. There should be at least two screws into the upright and one into the shelf.

Free units can be made from scrap for storage sheds, cellars, lofts and so forth. Timber shelving units may be made to be adjustable quite easily by resting the shelves on blocks secured to the uprights. One way of arranging shelves is to make cut-outs at each corner to accept the uprights. Making a template from cardboard is often useful.