Putting a Shelf Up Straight and Keeping It There

The points below about fixing shelves to a wall are ordered by how much difference they make, not by how often they get repeated.

Find out what the wall is first

Tap the wall and listen, since solid masonry sounds dull and dense while plasterboard over a cavity sounds hollow. Push a pin into an inconspicuous spot, because it will enter plasterboard easily and stop dead on brick or block. Plasterboard walls have timber or metal studs behind them at regular spacing, and fixing into a stud is far stronger than fixing into board.

Solid walls in older buildings may have a soft or crumbling surface layer, which means the fixing must reach the sound material behind it. Getting this identification right is the entire job, because the correct fixing follows automatically from the answer.

Choosing the fixing

Solid masonry takes a drilled hole and a plastic plug matched to both the drill bit and the screw diameter. Plasterboard needs a fixing designed for it, whether a spring toggle, a metal self-drilling anchor or a similar spreading device.

Cooking for one, a plain plug pushed into plasterboard has almost nothing to grip and will pull out, taking a section of board with it. Manufacturers publish load ratings for these fixings, and those figures assume correct installation and a shear load rather than a pull-out one. Use more fixings than the minimum, since load shared across four points is far more forgiving than load concentrated on two.

Drilling safely

Cables generally run vertically and horizontally from sockets, switches and light fittings, so those zones must be avoided. Use a detector to check for cables and pipes, sweep the whole area rather than one spot, and test the detector on a known cable first.

By the second month, wear eye protection, since masonry drilling throws sharp fragments and this is the most common DIY eye injury. Start slowly to stop the bit wandering, and use hammer action only on masonry and never on tile or plasterboard. If the drill suddenly runs free or you hit something metallic, stop immediately rather than pushing through to find out what it was.

Getting it level

Mark the first fixing point, then use a spirit level to mark the second rather than measuring both from the floor. Floors, ceilings and skirting boards in most buildings are not level, so measuring from them guarantees a sloping shelf. Hold the bracket against the wall and mark through the holes, which is more accurate than measuring the bracket separately.

Fit the first bracket loosely, level the shelf across to the second position and mark from there. Check level again after tightening everything, since tightening a fixing frequently pulls a bracket slightly out of position.

Load, and why shelves sag

A shelf deflects in proportion to the cube of the span between supports, which is why one extra bracket in the middle transforms it. Thin shelving material sags under books within months, and the sag is permanent once the material has crept. Books are far heavier than people estimate, and a full metre of shelved books is a substantial load on two fixings.

On a Sunday evening, support the shelf near the ends rather than at the very ends, since a small overhang reduces the deflection in the middle. Plan for the shelf being fully loaded eventually, because every shelf is, regardless of what it was put up for.

Buy the cheap version first; a month of use tells you whether it deserved better.

Renting, and the permission question

Most tenancy agreements restrict drilling into walls, and doing it anyway risks a deduction from the deposit at the end. Ask in writing and keep the reply, which is the difference between an agreed alteration and unauthorised damage.

On a Sunday evening, free-standing shelving needs no fixing at all except an anti-tip strap, which is worth using regardless of the tenancy. Tension rods, over-door hooks and adhesive fixings cover light loads without touching the wall, within their stated limits. Where you do drill, keep the plugs and fill the holes properly at the end, which takes fifteen minutes and protects the deposit.

Everything above, in order of what to do first

1. Find out what the wall is first. Tap the wall and listen, since solid masonry sounds dull and dense while plasterboard over a cavity sounds hollow.
2. Choosing the fixing. Solid masonry takes a drilled hole and a plastic plug matched to both the drill bit and the screw diameter.
3. Drilling safely. Cables generally run vertically and horizontally from sockets, switches and light fittings, so those zones must be avoided.
4. Getting it level. Mark the first fixing point, then use a spirit level to mark the second rather than measuring both from the floor.
5. Load, and why shelves sag. A shelf deflects in proportion to the cube of the span between supports, which is why one extra bracket in the middle transforms it.
6. Renting, and the permission question. Most tenancy agreements restrict drilling into walls, and doing it anyway risks a deduction from the deposit at the end.

The takeaway

Identify the wall, match the fixing to it, check for cables, and put in one more bracket than you think you need.

Living alone is a skill, and every skill looks like luck from outside.