Softwood boards: These are easy to have cut to the desired length and can hold many items, including heavy books. Plywood boards: This is made up of layered flat boards. The surface is often made to imitate a wood finish or it can be laminated. Particleboard or chipboard shelves: Made from wood chips glued together under pressure, these are common shelving boards that are lightweight, affordable and easy to find. It is best to get these cut professionally, as the makeup of the boards can blunt cutting tools. [1] X Research source Blockboard shelves: These are stronger than chipboard and are suitable for heavy duty items, like tools and appliances kept in the garage. Pre-made and pre-sized shelving boards: These are traditionally part of a kit and will often be made for adjustable shelves. The instructions for putting these together should always be included; if not, call the retailer or manufacturer.

Wood strips: Simple but effective, wood strips or blocks can be used to keep shelves in place. A strip of wood used at both ends of shelving is known as a cleat support. It can be neatened by nailing a piece of wood across the front shelf to hide the side cleats. Metal strips: Available from hardware stores, these can be used as shelf supports. They aren’t that pretty, so they may be best for hardware storage in the garage or cupboards. Brackets: Typically L-shaped, these can be fancy or plain. They are simple to use and are usually good for a variety of shelves. Some brackets are so fancy that they can enhance your décor but they will usually cost a lot more than plainer versions. [2] X Research source

You can also use cinder blocks, in which case you’ll only need one on each side rather than the two bricks.

There should be two bricks on each side of the shelf to support it.

This time, add two sets more bricks on top to make a pillar. Do the same for the other side.

If you want to strengthen this structure, add a cross-brace to the back of the shelf unit, screwing it into the shelf boards.

Use a masonry drill bit. Drill to the depth that the screw requires to penetrate the wall sufficiently. Insert a wall plug.

Shelf boards. The shelf boards should be at least 2cm 3/4" thick. Supports for the shelf boards. Cleats (strips of wood) are easy and ideal for this unit. Two vertical support panels. These form the sides of the shelf unit. A top piece. This needs to be slightly wider than the shelf boards, so that it can be hammered or glued on top of the unit. A piece of hardboard for the back of the shelf unit. (Ask the timber merchant to cut to size if you can’t do this yourself. )

When you’re decided on this, cut the shelf boards to this width, if they’re not already at the right width. Cut the vertical support panels to the right height, if they’re not already done.

Repeat for the second vertical piece. This forms the first shelf support.

Decide where you want the rest of the shelf boards to be place all the way up the first support. For each level, use a shelf board to help you measure the exact positioning of the cleat across to the opposite vertical support panel (this helps to ensure it is level), and mark it. Repeat the measuring and marking for each shelf level being added.

If nailing or screwing into position, be sure to use nails or glues that don’t penetrate through the vertical support panels––they must remain wholly within the panels.

If you need to be able to dismantle the shelf, do not glue the top piece in place. Instead, use screws that can be easily undone and re-fixed after each dismantling and reassembly.

Another solution is to use a cross-brace instead of one piece of board. Use whatever fits your needs best.

See also How to install a shower corner shelf if you’re looking for a bathroom shelf solution.