Three generations of my family, my Great Grandparents, my Grandparents, and my parents each used an earthen root cellar to store a plethora of garden produce, canned preserves, cured meats that lasted a full year or more until the next harvest. 

Prior to the introduction of electricity in rural America, root cellars were the means of storing food long before the refrigerator and freezer were common household appliances.  Traditionally, the root cellar (or cold room) was an underground space built under or near the home, insulated by the ground and vented, so fresh cold air could flow in and warm air out.  Then, when sub-zero winter temperatures arrived, the vents were closed or plugged up, and the cellar stayed cold but not freezing. 

Unfortunately, most modern basements are too warm for long-term winter storage of garden produce.   However, a basement can be used for cold storage and that is why, when we began planning our homestead build a few years ago, one of the requirements included a functional root cellar capable of storing an assortment of garden produce held over from the summer/fall harvest.   In addition, in keeping with our homesteading values, the root cellar had to be designed so that all energy inputs to heat or cool the space were minimal (if any at all). 

The following is how we made our root cellar that fits into our homesteading lifestyle. When we initially designed our home, we decided to build a full basement rather than a crawl space foundation to allow for things like a root cellar.  In days past, root cellars were dug into the earth where the soil would insulate produce from the heat, cold, and dry air.   

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That is the principle.  However, our house is super-insulated plus the hydronic heating system keeps the basement toasty.  So, to ensure root cellar stays cold enough, we attached a powered bathroom style fan to the exhaust venting that automatically turns on to exhaust warm air and in turn draws in cool air through the fresh air inlet vent (via convection – warm air rises and is replaced by cold air).  The powered exhaust vent is wired to a universal electronic temperature control (see photo below) that has programmable “cut-in” and “cut-out” settings. 

There are several universal truths that remain constant and will help you create this type of optimal system even though every basement situation is unique.  
     1.  Location.  You will need access to the outside for fresh air, so choose a location  that has a window (remove the glass and install plywood to run pipe through) or one that will allow you to bore holes through the basement wall for the 4″ vent pipes.  In colder climates you can create an insulated panel to replace the glass by simply laminating a layer of 1/2″ thick exterior grade plywood to each side of a piece of 1-2″ thick polystyrene foam and then running the pipe through it.  Glue the sandwich together using polyurethane construction adhesive.
     2. Walls.  After picking your location you can turn your attention to the walls.  Things to consider include the size of a door (30″, 34″, 36″ …) you will use, how long and how wide the root cellar should be (that all depends on person choice and the amount of food you plan to store), will you use shelving, etc.  The possibilities are endless so take time to write all your ideas down before starting.  Our root cellar is roughly 13′ x 6′.  We utilized standard 2″ x 4″ lumber with 16″ OC spacing, sheet rock, and a 30″ re-purposed wood door.  One note:  it is always a good idea to use treated lumber on a concrete floor in case of damp conditions.
     3.  Insulation.  To keep the root cellar at the proper temperature you will more than likely need to insulate.  We used traditional fiberglass bats because we live in such a dry climate.  Moisture is your most important consideration.  If you are likely to get damp conditions for any reason, understand that fiberglass has almost no ability to resist mold growth and deterioration  when water is present.  Foam tolerates moisture much better.  Extruded polystyrene is especially good in this regard.  And don’t forget to insulate the ceiling.  Warm coming down from heated areas above will raise the cellar temperature too high.
     4.  Venting.  The key of a basement cellar is the two-vent design.  To function best, space the interior ends of the intake and exhaust pipes as far apart as possible.  Also, plan your shelving layout allowing as much air movement as you can achieve.  The cold air inlet should be designed so that the air is delivered as close to the floor as possible.  The exhaust vent should be located in or near the ceiling and exhausted to the out side.  If necessary, add a small power fan to the inlet pipe and/or the exhaust pipe to maintain temperature.  Last, be sure to cover the vent openings with screen to keep out insects and mice. 

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Your dreams of having an ideal root cellar is a venture worth planning for and the reality is, with a bit of planning, you can build your own root cellar and enjoy the bounty of your harvest for a longer time.