While hanging shelves is a fairly simple process, joining shelves in a corner is a more challenging task. It will require a little extra time and possibly specific tools, depending on how you choose to join the shelves. Following certain methods done by other wood working professionals can make the challenge less intimidating and give you good results.
Before you attempt to attach shelves, confirm the shelving ends you are adjoining together are square. If not, they won't attach correctly and will you end up with a large seam.
Choose which method you will use for joining your shelves. The first method is the biscuit method, which is one of the best ways to join the shelves, but requires the right machinery. You will need a biscuit machine to cuts slots in the leading edges of the shelf boards. If your shelf is between 8 and 12 inches in depth (from front of shelf to back wall), you will need a minimum of 2 biscuits. You will also cut a similar slot in the adjacent shelf. If using a shelf board with a depth of 12 inches, measure in 3 inches from the front and 3 inches from the back of the shelf and make a hash mark. Take the adjacent board and put them together and transfer the mark to the other board. Now you are ready to cut the biscuit slot.
Biscuits come in various sizes. Set your biscuit machine by splitting the difference on the thickness of the shelving material. For example, if using a ¾ inch shelf board split the difference or ½ the height and set the biscuit machine at 3/8 of an inch. Note: depending on the thickness of your shelf, the setting may vary.
Cut the slots for the biscuits. You should have two slots on each inside edge of the shelves that will be joined or a total of four slots. Place wood glue on edges of biscuits and insert into slots. Also glue the edges of the shelves where they join. After 24 hours drying time, you can hang the shelves.
Another method is by using dowels with the same principle except placing a wooden dowel rod instead of a biscuit. Drill the holes with a small doweling jig. The jig helps center the hole on the shelf board. You should have just as much support, if not more, using the dowel method as with the biscuit method.
Bracket and Shelves
The third method and possibly the easiest for the average homeowner is to bracket the shelves from underneath. Use 4-inch long brackets approximately ¾ inch in width. Evenly space the brackets across the bottom seam where the shelves intersect. Use at least two screws in the brackets on each side of the seam. This should provide enough support.
Attaching Shelves to the Wall
"L" brackets will provide the simplest method for attaching shelves to the walls and adequate support. It is important to place the appropriate number of brackets, depending on the weight capacity and the use of your shelves.