Before you can design your shelving project, you need to first assess your storage needs. Start by looking at the items you have stored in the garage. Separate those items into piles -- one for items you truly need to keep and one for items you can get rid of. Then, hold a garage sale or call the local junk hauler to clear out those unwanted items. Once you know how much stuff you really need to store, you can more forward and determine how many shelving units you need.
If you have heavy items to store, be sure that the shelving units you build or buy can stand up to those heavy weights. Checking the weight of your tools, car parts and other items will help you determine which kind of shelves you need for your project. Look at the weight rating of each shelving unit you shop for, and always buy shelving units with a higher weight capacity than you think you will need.
If the items you will be storing are relatively light, you can simply line the walls of your garage with freestanding metal shelving units. But if you plan to store heavy or bulky items, it is best to anchor those shelving units to the wall. You also need to anchor those shelving units properly if you live in an area that is prone to earthquakes. If the shelving units are not properly anchored, they could fall and cause damage to your garage -- or injury to your family members.
If you need to devise a shelving solution for your garage, you have two choices. You can purchase a ready-made shelving solution in the form of metal or wooden shelves and simply put them in place in your garage. Or you can build your own custom-made shelves. Making the right choice means assessing your own construction skills, as well as comparing the price of the materials needed to create the shelves to the purchase price of those ready-made units. If you need to store very heavy items, you might have no choice but to build your own shelves, because the weight capacity for ready-made shelving units can be limited. But if your storage needs are more basic, it may be just as cost-effective to buy some shelves and attach them to your garage walls.