Walk-in coolers are not the same as walk-in freezers. Walk-in coolers are giant refrigerators that can range from walk-in-closet size to warehouse size. Businesses use walk-in coolers to store fresh flowers, vegetables, meat and dairy products. Individuals sometimes build walk-in coolers to store food and drinks in larger quantities. These coolers are in the range of 30 to150 square feet of floor space. Building your own walk-in cooler does require some carpentry skills and a considerable financial investment.
Measure off the length and width for the walk-in cooler with a tape measure and mark the corners. Stretch a chalk line from one corner to the next and lift the string and let it snap down to leave a chalk mark indicating the location of the wall. Do this for each wall.
Use a carpenter's square to make sure the corners are square by laying it on the corner with the legs going down each adjacent line. It is best if you can install your cooler as a small room inside a larger room or in a basement or garage. This will reduce the load on the cooling unit when it is installed.
Compute the number of studs that you will need by dividing the number of inches in the length of each wall and dividing by 16, then add one to that number per wall. Divide the length of the wall in feet by eight. Round up to the next number on each wall. Double that number and add the answer to the previously computed total. If you are going to put in a 4-inch raised floor, follow the same pattern for the floor and ceiling. You will need a stud for each floor joist and studs at each end to nail to. Buy enough rigid foam insulation to fill up the entire space between the studs and even for under the floor. Plan on building your own door as a hinged portion of the wall.
Construct the floor by cutting the studs for the floor joists 7 inches shorter than the length of the floor. Nail the studs to the studs that will be acting as the ends to the floor panel on 16-inch centres. Lay the floor in place inside the chalk lines that you previously made on the floor of the room where the cooler will sit. Build the ceiling just like the floor and lay it on top of the floor when it is finished. Construct three of the walls in the same way that you made the floor and ceiling. Stand them up and nail the ends of the floor into the upright studs of the wall. Drive nails through the bottom plate of the walls and into the floor of the room.
Lift the ceiling panel to the top of the walls and nail it in place to the studs and top plate of the wall. Nail the top plate of the walls to the ceiling of the room if the cooler is that tall. Cut the foam insulation one-quarter-inch larger than the space between the studs. Force it into place for a nice, tight fit. Make sure that you fill up the wall from inside to outside. Do the same for the floor and ceiling.
Cut quarter-inch particle board to fit on the inside of the walls and the underside of the ceiling. Nail or screw it into place. Use five-eighths-inch particle board for the floor. Cover the outside walls with quarter-inch plywood so it can be painted with a better finish.
Construct the fourth wall but leave two sequential studs out of the middle of the wall. This will be your door. If you need larger than a 32-inch door opening, adjust the studding accordingly. Read the instructions with your air conditioning unit that will cool the cooler to see what size opening is needed for installing the unit. Build a frame in the fourth wall two studs over from the door opening to hold the air conditioner. Make the top of the opening 1 foot from the bottom of the ceiling. Add a second stud next to the stud that will hold the door hinges by nailing to that stud.
Build the door in the same style as the wall with a bottom and top plate and studding. Cut pieces of studding to make braces that will run from side to side between the studs of the door. Cut insulation and fill in all of the opening on the door and fourth wall except for the air conditioner opening. Cover the inside and outside of the wall and door with the same type of materials used on the walls. Fasten the door to the edge of the door opening with hinges that are screwed to the door and wall. Use a hasp type latch to hold the door shut. You can buy the kind that can be locked if you prefer.
Caulk all of the seams around the inside and outside of the walk in cooler. Prime and paint the outside of the cooler with your favourite colour. Read the directions on the thermostat override that you will need to install in the air conditioning unit to allow it to cool below 12.7 or 15.5 degrees C. This device will keep the fan running to dry the cooling coils and allow the unit to cool your cooler to the desired 1.66 to 4.44 degrees C. Put the air conditioner in its opening and install the bracing that came with the unit to keep it stable. Plug it in and your cooler is in business.
Make sure that the floor is well insulated because your cold air can escape easiest there.