As the design stages of the root cellar progress, I took the time to do some research and consult some do-it-yourselfers along the way. If you are serious about constructing a root cellar, check out the book Root Cellaring: Natural Cold Storage of Fruits and Vegetables. It is one of the few comprehensive books on root cellars out there.
The book outlines 5 major components of root cellar design:
- A root cellar should borrow and keep cold.
- Use any of 3 effective cold air ducts: a window, louvered ventilator, or exhaust pipe with plug to close of pipe when needed.
- Maintain temp between 32-40 degrees.
- Build on southern exposures for easy winter access.
- Insulate inner walls, door and ceiling…
- Vapor barrier on the outer, warmer side of insulation
- Use a gravel or dirt floor.
- Sprinkle water on the floor, spread damp burlap bags over produce, or put pans of water in the cellar to increase humidity.
- Smooth ceiling surface- no exposed/projecting beams
- Adjusting air intake helps to reduce excessive humidity and to help chill area to the desired temperature
- Air circulation removes vegetable odors and ethylene gas emitted by stored fruits
- Air intake placed at low opening, and air outlet placed on opposite wall with a high opening
- Use plastic draining pipes and screen openings to keep out rodents. For an 8′ x 8′ cellar, use a pipe 6″ in diameter
- In places where snow accumulates, make sure the doors opens inward.
- Be conscious of the avg. winter snowfall/ amount of drifting for your area
- Perforated 4″ drainpipe running along the perimeter of the cellar, bending around both corners and ending at daylight. (Pipe should have a slope of at least 1″ per 8′.
- Drainage prevents pressure on the rear wall of the root cellar from expansion of frozen wet soil.
- Use french drains!
After extending research to various DIY-ers (big thanks to Survival Acres), I found some more useful info:
- Ensure that the location has good draining and keep as much water away from the cellar as possible.
- Water will find any excavation you make (pits, trenches) and this is the first place water will pool up, so make sure that any excavation drains away. And try to make sure that the excavation you want to stay dry has sufficient drains around it.
- French drain around excavation and make sure that it is flowing downhill and away from the cellar.
- Slope the root cellar floor just enough so water can drain out.
- Use diversion ditches and drywells to divert more water.
- Know your soil index… sandy soils naturally drain better than silty/clayey soils.