A sagging shelf is unsightly and can eventually break, damaging your kitchenware, collectibles or books. A loose shelf presents the same danger. Stabilizing a sagging or loose shelf involves supporting the shelf with either two pieces of wood or a bracket. Both methods are effective and can be accomplished easily with little woodworking knowledge. Even though they're simple and direct, the fixes should last as long as you need them to.
Stabilizing a Sagging Shelf
Measure the distance between the bottom edge that's not sagging and the top edge of the shelf or surface below it.
Remove all items from the shelf and the shelf from the cabinet.
Mark the measurement from Step 1 on two pieces of 1/4-by-1-inch wood.
Cut the wood with a saw. If you want to, you can stain or paint the wood to match the surrounding wood.
Cut two-sided tape to the same measurement you took in Step 1.
Stick the tape onto the 1-inch sides of the two pieces of 1/4-by-1-inch wood.
Adhere one piece of the cut wood and tape to the inside of the cabinet's center support. Adhere the other piece of cut wood vertically to the back of the cabinet, directly in the center.
Place the shelf back into position. It will now be supported in the middle by the two pieces of 1/4-by-1-inch wood.
Stabilizing a Loose Shelf
Measure the distance from the bottom edge of the shelf to the top edge of the shelf or surface below it.
Remove the contents of the shelf, and then the shelf.
Mark the distance measured in Step 1 at the spot where you'll be placing the new shelf support. Use a carpenter's level to ensure your mark is level with the existing shelf supports.
Line up the new shelf support and mark where it will be placed.
Drill a pilot hole for the screw that came with the shelf support. If the shelf support came with a nail, skip this step.
Secure the shelf support with the screw or nail provided. Put the shelf and its contents back into place.