How to Square a Bookcase

Squaring a bookcase will keep everything in its place.

Few things are as irritating as a bookcase with slanted sides. When a bookcase appears to lean, not only is it awkward to display items on the shelves, but it stands out from the other furnishings in the room and makes everything look a little off-kilter. Fortunately, it is not difficult to square a bookcase. It is easiest if you are building the bookcase from scratch, but even an existing out-of-square bookcase can be repaired using this simple technique.

Things You'll Need

• Measuring tape
• Partially assembled bookcase
• Bookcase back
• Hammer
• Nails

Instructions

1. Lay the bookcase face down on a level surface. If you are building a bookcase from scratch, assemble the top, bottom, sides and shelves -- if the shelves are secured to the sides and not adjustable -- before performing this series of steps. Do not install the back or add any trimwork. If you are working with an already-built bookshelf, remove its backing.

2. Measure diagonally from one corner of the bookcase to the opposite corner, using the measuring tape. Make note of this measurement; write it down if necessary.

3. Repeat the process, measuring the distance between the two remaining corners of the bookcase. Make note of this measurement.

4. Compare the two measurements. If they are equal, the bookcase is square. If the measurements are not equal, continue to the next step.

5. Determine which of the two diagonals has the longest measurement. You will adjust the bookcase using the corners on that diagonal.

6. Apply light pressure to both corners as once. Butt one corner against something immovable, like a wall, then gently push on the other corner with your hands. Do not overdo this. If you push until this diagonal is shorter than the other, you will have to reposition the bookcase so you can try the adjustment along the other diagonal. If you have to switch between them several times, you will cause the bookcase's joints to loosen.

7. Recheck the measurements across both diagonals of the bookcase. If they do not match, repeat Steps 5 and 6 until they do. When the two measurements match, the bookcase is square.

8. Attach the back of the bookcase, using the hammer and nails, being careful not to knock the newly squared bookcase out of alignment. Once attached, the back will keep the bookcase square.

Tips & Warnings

• If you want to make your bookcase extremely sturdy, use glue in addition to the nails when mounting the back.