2011 - Volume #35, Issue #4, Page #03[ Sample Stories From This Issue | List of All Stories In This Issue | Print this story | Read this issue]
Grain Bin Root Cellar Doubles As Storage Shed
"I wanted an inexpensive building that would serve as a root cellar for our vegetable crops on the ground floor and be tall enough so we could build a second floor for storage, drying fruit and raising poultry," says Scott Brodie, who along with his wife Brynn, operates Red House Farm. "I figured that since a galvanized grain bin is just a giant culvert, it certainly should hold up if part of it was buried in my sandy soil," Brodie says.
The Brodies started the project by spending just $400 on a dismantled 20-ft. tall bin after running a classified ad in the local paper. Scott learned on the internet that people had renovated bins for living quarters, but nothing turned up for burying a bin 8 ft. in the ground.
"I knew there would be side pressure on the wall from backfilling 8 ft. of sand, just like a basement wall or a retaining wall," Brodie says, "so I had to devise an internal support system." His design inspiration came from the hub and spokes of old steel wheels.
After Brodie excavated a hole about 9 ft. deep and 2 ft. larger around than the bin, he drew the circular outline of the bin wall in the bottom of the hole. He dug 8 postholes around the inside perimeter of the circle and one in the center. "The perimeter postholes are 7 ft. apart and about 3 ft. deep," Brodie says. "Each one is filled with concrete and a couple pieces of rebar sticking out the top to hold the support posts."
After assembling the bottom 8 ft. of the bin walls in the large hole, Brodie bolted 6 by 6 by 8-ft. tall support posts to the footings. He then attached floor joists and lateral braces from the top of each post to a 16-in. dia. hub log at the center. The 2 by 6 floorboards screwed to the joists tie the whole support structure together.
"The key to backfilling the hole without deforming the bin is to build the wooden post and beam structure before backfilling," Brodie says. "After backfilling we put down the 2 by 6 floor, then added the final courses and the roof.
"Cutting openings in the bin for windows and doors is okay if you don't overdo it and structurally alters the integrity of the bin," Brodie says.á
"After cutting the openings, we built a wooden framework on the interior to regain the structural integrity lost by removing metal. A wood stove provides supplemental heat and cooking. Together the two floors provide more than 500 sq. ft. of usable space in the bin.
"For moisture protection we put two coats of membrane sealant on the outside of the buried walls and a vapor barrier in the ceiling," Brodie says. "With an insulated door and ventilation, it's ideal cold storage for potatoes, turnips, beets and canned products. This winter, when the outside air temperature was around 0, it was still 33 degrees in the cold storage."
Brodie used 5 extra sheets of corrugated side-wall steel to create an attractive and functional curved roof over the root cellar stairway. The post and beam roof structure also supports the 8-ft. stairway sidewalls. He added a row of glass blocks underneath both sides of the roof stringers, along with natural rock landscaping to finish off the project.
"I have to think that on a per-foot cost basis, this bin creates much cheaper root cellar space than a conventional masonry structures," Brodie says. "We can easily regulate the temperature and humidity in the lower level with a fan, and in the upper level we can open windows, the roof and the door. The bin seems incredibly sturdy in high winds and I think it's going to last a very long time," he adds.
Brodie says the bin project cost him about $1,000
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