Shelving near you

A shelf fails at its weakest link, and that is usually the fastening in the wall rather than the board. Screws driven into wood studs give the most dependable hold, which is why heavy shelves are laid out so the brackets or rails land on studs. Where no stud is available, hollow-wall anchors can carry lighter loads, but only within their maker's rating for that wall material and that direction of pull.

Depth matters as much as weight. The farther the load sits from the wall, the harder it levers the top fasteners outward, so a deep shelf of books pulls on the wall much more than a narrow one carrying the same weight. Floating shelves feel this most, since the hidden support resists that leverage alone; unless they're fastened firmly into framing, they suit lighter displays. Steel studs, plaster and masonry each need their own hardware, as the picture and art hanging page explains.

The board decides how a shelf looks, how it takes paint or stain and how much it bends between supports over time. A shelf that sags a little more each month is telling you the span is too long for the material and the load; an extra bracket, a stiffening strip along the front edge or a thicker board fixes it.

A freestanding bookcase or shelving unit doesn't hang on the wall, but a tall one still needs to be tied to it. Health Canada names bookshelves among the furniture children may try to climb, which can bring it down on them. It recommends angle braces, safety straps or other anti-tip devices, fastened to a wall stud or with heavy-duty drywall anchors made for that type of furniture. It also advises putting heavier items, such as books, in lower drawers so furniture doesn't become top-heavy, and the same logic applies to the bottom shelves of a bookcase.

Empty the shelf as soon as any of these appear. Driving new screws into the same holes rarely lasts: the usual fix is new fasteners into studs, more supports or a lighter load, with the old holes patched.