You can build walk-in freezer units in a range of different sizes, with different materials and to suit varied purposes. It is possible to create a small walk-in freezer in one section of a room, or develop an industrial-scale freezer that spans a much larger space, such as a warehouse. A large-scale freezer with plenty of room for walking around is required, for example, in a food-development company, but it costs significantly more to create.
Select the size of freezer you need for your individual requirements and purchase a walk-in freezer kit that can create such a freezer size. Make your own from scratch using insulation, sheet metal and foam. You will need to be skilled in cutting sheet metal to successfully complete the latter option.
Choose and purchase insulation material and a metal skin. Use extruded polystyrene (high moisture resistance) and polyurethane in large freezers as insulation materials, according to US Cooler. If you are looking to build a small-scale, in-room freezer, choose a skin that is easy to clean, robust and solid, such as G90 galvanized (expensive), aluminum (resistant to corrosion), galvalume (steel-coated aluminum), painted G90 (several color choices) or stainless steel (very expensive, but strong).
Create the walls and roof of the freezer by cutting sets of sheet metal, inserting the insulation materials and injecting foam to clamp the two components together. A kit will already have the walls sandwiched together.
Purchase and install a refrigeration system that is both economical and energy-efficient. Select either a remote-control system, a pre-assembled remote system, a standard mountable system or a location-specific system (such as mount-top, saddle-mount, penthouse or roll-up).
Decide whether you need a floor to the unit, and install one if you do. Sweep the mounting surface clean, lay a sheet of waterproof sheathing down to create a moisture barrier and place the flooring on top. Secure the walls and floor with tongue and groove connectors, bolts or screws (and a screw driver), depending on the kit, or the type of joint you prefer to use.
Fit a door to the freezer. Take into account its position in the room and the side you wish to enter it from. Kits have ready-made doors that attach to existing hinges, but you can make your own using hardware store hinges. Make sure the door insulates, too. Caulk all the static joints.