The Daily Fix: Support a Sagging Shelf

The bookshelves in my home office have seen better days. Years of overloading them with heavy books and electronics have left some of the shelves looking decidedly droopy. They're still in good shape, though, so I didn't really want to replace them. Instead, I just added a couple of basic metal brackets underneath each shelf. Here's how:

Step 1: Measure the problem shelf. In most cases, one bracket centered and attached to the underside of the shelf will provide enough support to remedy any sagging.

Also determine what the shelf is made of. Chances are it's either solid wood, plywood, particleboard or fiberboard. Next, decide how you will anchor the bracket. If you're attaching it to the wall, will you be drilling into drywall, plaster or a wooden wall stud?

Step 2: Purchase bracket and hardware. Visit the hardware store and select an appropriately-sized metal shelving bracket. Now here's the really important part: be sure to choose suitable mounting hardware. The sturdiest metal bracket will be rendered useless if it's not anchored rock-solidly to the wall.

Specifically, skip those little colored plastic drywall plugs and get some plastic or metal self-drilling anchors instead.

Step 3: Attach bracket to shelf and wall. Empty the shelf of all its contents. Use a tape measure to locate the underside-center of the shelf and mark that point on the wall with a pencil. Next, position your new bracket at that center point, and line it up so that it is level with pre-existing brackets on either side. Use your pencil to mark the screw holes, then take down both the bracket and shelf.

Screw drywall anchors into the points you have marked. If self-drilling anchors are hard to start with, drill 1/8-inch pilot holes and try again. When the anchors are flush with the wall, hold the bracket back in position and install the screws. Replace the shelf and you're done!

What about free-standing bookcases? If the bookcase is a quality piece, you should be able use wood screws to attach the shelving bracket to the case's back side – if it has a back side, that is. Reinforcing cleats are another, less common, option.

Unfortunately, if you're dealing with a cheapish particleboard bookcase, the back side will either be too flimsy to hold a bracket ... or there simply won't be a back side! In that case, you could look into buying or making simple hardwood or metal reinforcing strips (sometimes called "lipping" or "edging strips") to screw into the underside of the sagging shelves.

What if my shelf is still sagging? If a shelf has been overloaded for too long, and if it's the kind that rests in position (instead of being screwed onto the wall or the rest of a bookshelf), it may have become permanently warped. In that case, your only option may be to replace either the shelf or the entire unit.

Helpful Hint: If you're thinking of major bookshelf repairs or a shelf-building project, check out The Sagulator. This useful (and free!) online tool will help you calculate the support your structure will need so you can avoid ever having sagging shelves in the first place!