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Earthbag Root Cellar Provides Lots Of Cold Storage
Sherry Rovig says the covered dirt mound in her backyard looks a little like a Hobbit House, but it’s actually an amazing above ground cold storage root cellar that works great even in the below-freezing winter weather she experiences in Duluth, Minn.
The earthbag structure encloses a 10-ft. dia. room with 6-ft. walls topped by a wooden roof insulated over the top with styrofoam and dirt. During January’s sub-zero temperatures, the cellar stays between 35 and 38 degrees and 90 to 96 percent moisture - perfect for the potatoes, apples, beets, Brussels sprouts, carrots and other produce from her large garden.
“We have a high water table and it’s all clay, so we couldn’t just dig it into the ground,” Rovig says.
With the help of family and friends, Rovig created a raised tamped gravel pad and then built up walls using bags filled with dirt. She notes that earthbag construction is used by some people to build homes (www.earthbagbuilding.com). Sandbags are filled with damp soil that contains 5 to 30 percent clay and then stacked like bricks. Two rows of 4-pronged barbed wire placed between the layers help stop the bags from slipping apart. The bags are firmly tamped down so when they dry they are rock-hard and fit tightly together, similar to adobe.
Road base with suitable clay content was used to fill the bags. The polypropylene bags fit over a bag stand positioned on top of the wall. The bags were filled in place on the wall and then slid into the desired position. Rovig used a large tin can to fill the bags.
Wooden cleats sandwiched between layers of bags create attachment points for the door and shelving. A wooden top plate was secured to the wall with 24-in. long pieces of rebar driven at opposing angles down into the walls. The roofing was attached with screws to a center ridge beam and top plate. Then a heavy rubber tarp was pulled over the top to provide a waterproof seal.
A loader tractor was used to cover the entire structure with dirt. The root cellar - which can also be used as a storm shelter - spreads out to about 30 ft. at the base with about 6 to 10 in. of soil on the top. Jute and straw covered it the first winter, but the goal is to sow a cover crop on the mound this year. Also, the tarp in front of the door will be replaced with a second door to create a buffered entry.
“We have vents in the door and an exhaust vent. And, we have electricity to it for a light and outlet,” Rovig says. Carrots and leeks are in sand-filled totes on the floor, while shelves hold the other vegetables. Apples are at the top so the ethylene gasses they release go up and don’t affect the other produce. Rovig notes that the environment isn’t right for squash, so it is kept elsewhere. With a deep coat of snow, the root cellar was well insulated and stayed above freezing.
There are many resources for earthbag construction on the internet, and Rovig highly recommends the method as an economical building method.
Contact: FARM SHOW Followup, Sherry Rovig (earthyurt@gmail.com).


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2020 - Volume #44, Issue #2