Root cellars have been a part of life here in Southern Alberta for a hundred years. And there have been some big ones. Mrs. Crest, who contributed to the meat curing page, told me when she was a kid her Uncle had a root cellar with over 500 bottles of fruit in it, along with the usual fare of vegetables. Although there are not as many root cellars around now, they are still extensively used here for storing potatoes, carrots, apples, and in the fall of the year, other garden produce as well.
The first root cellars were usually dug with a pick and shovel. (In 1965 I used the front end loader on my tractor to dig the root cellar I’m using now.) The only wall we had to build was the front wall the door was in. The other three walls were formed by the dirt from the hole we dug. I made the roof with three logs as supports, then I laid 2X10 planks over them and nailed them down (See illustration). Over the top of the roof I put about 2 feet of dirt, with grass eventually growing on top of it. The front wall was also made from 2 inch lumber. Unlike the drawing, this wall extends up another three feet (see photo). The stairs were made with these same planks, as well as the side walls on both sides of the stair case. The planks in the roof, stairs and front wall were all made from rough, unplaned lumber, actually 2 inches thick.
You will notice from the photograph there is an upper door and a lower door. It is important you do this as each door adds greatly to how cool the root cellar will be in the summer time and how warm it will stay in the winter. The lower door on my cellar is constructed with a sheet of 1/4 inch plywood on each side filled with insulation. The upper door is tilted slightly so water will run off when it rains, and so it will be easier to find in the snow. To prevent rain from dripping down between the outside of the cellar and the top of the door, I use a couple of pieces of tin that are wide enough to hang over the top of the closed door after being wedged in between a couple of the planks on the outside of the cellar. This helps a lot. The upper door is constructed from two layers of 3/4 inch rough lumber. There is no insulation in it, and it has a layer of tin nailed to the top of it to keep it water proof. This door is hinged to the stairs side wall on the left side and is hinged so it can swing all the way around and lay on the grass.
Our main reason for having a root cellar is to keep our vegetables from freezing in the winter. We have very cold winters. For example, last winter we had several days when the thermometer dropped down past 40 degrees below zero F. How well has out cellar worked over the years? Very well. Nothing ever froze, except for once, and then it wasn’t the cellar’s fault. On one of the coldest days last winter, I went to get some potatoes and carrots and was surprised to find the lower door open. Even with this, only a small part of the potatoes were frozen. After closing the lower door the temperature rose to above freezing again. I have never tested the temperature in the cellar during the winter time, but in the summers the temperature hovers around 51 degrees F. This is a bit cooler than the temperatures you would expect to find in a root cellar in the warmer parts of the USA. This is because our hottest days in the summer are only around 90 degrees F. And the cold winters tend to keep the ground a bit cooler throughout the year.
Last year my center cross beam in the roof broke right in the middle. The dampness from the earth above it had gradually rotted it over the years. I did not waterproof my roof when I built it, and should have. After it broke, we jacked up the center of the roof and put in a vertical support beam in the middle of the room. This should help the cellar last for several more years.