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Retro-fit in floor root cellar ideas anyone?  RSS feed

 
Steven George
Posts: 18
Location: Finland, Minnesota Zone 4a
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So, we live in a rather small house (about 280 sq ft) and we plan on eventually (5 to 10 years) building a much larger house with better thought out everything etc....  But for now, we need a place to store squash, potatoes, kraut etc from our harvest...  We live in a pretty cold climate (zone 4a) and our house is built on sonotubes with an uninsulated  but fairly sealed treated plywood skirt between the tubes.  So here's what I'm thinking of doing for a root cellar that is "good enough for now".  Cutting a hole in the floor and digging down to bedrock (about 1 or 2 feet) and then putting some gravel down to level the hole, dry stacking cinder blocks up to the floor joists and then lining the outside of the cinder block wall with pink foam and then banking up some the the dug up dirt on the outside of the foam and calling it good.  I'll definitely insulate the floor door with pink foam as well.  I was also thinking of possibly running a couple 2 inch pipes in from the outside to create ventilation since I've read that's important.  If I do that I would be sure to put hardware cloth up to block critters. 

Another thing to mention, we're off-grid with a relatively small solar array so any electronic gizmos are not really an option.  And like I said, this is really only a "temporary" solution to our harvest storage, so I don't need to get too fancy. 

Anyhow, I was thinking I would put the pink foam on the outside just so I don't have to look at it, but would there be any advantages to having it inside the wall instead?  Any other thoughts or ideas in general about the design etc?  I do want to keep it simple and relatively cheap, but I am not set on this design and I am certainly open to other ideas or tweaks. 

Thanks in advance for any input!
 
Taryn Hesse
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Location: Rainy Cold Temperate Harz Mountains Germany 450m South Facing River Valley
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Hi Steven George

I have campers who put in rain barrels burried up to the lid under the trailors for refridgeration and it keeps a relativly constant cool temperature 5 to 10 C. Lots of ground water flows through the soil (a few meters away from a river) so there is no drain and it needs to be opened every few days to vent. If its dry enough you could just bury an old fridge or freezer and put in a downwards reaching pipe to let any condensation drip away. Broken fridges and freezers I would think would be free (I find them at the dump ) and its a similar idea but pre-built being mostly insulation foam with a cleanable surface. Some from resturaunts even have locks and would keep racoons and children out. I don´t know what usda zone im at but it freezes between -10 to -20 C every winter and things don´t freeze in the barrels outside. I also think you might want to take the piping from the back off first im not sure what is inside of it.
 
Mike Jay
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Location: Northern WI (zone 4)
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I'm sure that design will be perfect for some portion of the year.  I'm just not sure which.  IE, it will possibly be too cold in Jan and too warm in April.

For comparison, I have a root cellar in my basement.  One wall is the uninsulated block wall, the other three are cement walls with R10 styrofoam.  Ceiling is R10 pink as well.  I have two 4" vents and a duct fan to force air through as needed.

I struggle to get it cold enough until mid November.  I have to run the fan whenever the outside temp is lower to try to cool it off.  I'm in northern WI so it does get chilly here.  Once it gets cold, I'm good to go until Jan/Feb where if I get enough -10 at night, the root cellar can get down to 33 degrees and I have to crack the door to keep it from freezing.

Given my experiences, I'm guessing that burying yours will give you some moderation of temps but will delay the point at which the temps are "low" enough for good storage.  I'm guessing your crawlspace gets pretty cold in January?  Considering 3 sides and the top of my cellar is surrounded with 60 degree air, one side is frozen soil and the bottom is 40 degree subsoil and I have troubles with freezing, I'm thinking yours may freeze solid from mid Dec to mid Feb.

I'd suggest that you think about not putting insulation above the cellar and plumb a vent to the inside so you can send warm air down there if it gets too cold. 

Alternatively, have you considered a "normal" root cellar?  Just digging down a bit and allowing snow to cover/insulate it in the winter could be the fix.  By putting it in your crawlspace, it may have colder air above it than if it has a foot of snow directly on top of it.

Sorry I'm rambling...
 
Steven George
Posts: 18
Location: Finland, Minnesota Zone 4a
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Thanks for the thoughts. 
Taryn, a barrel or even a fridge is a bit smaller that I would probably need.  Also it gets quite a bit colder here that where you are, our frost line here is below bedrock everywhere around our house, so no way to dig below the frost line.  Coldest it has been so far this winter was about -31 C.  I do like the idea of a free pre-built already insulated box though, too bad I need more space. 

Mike, good point with the possibility of needing to heat it during the winter.  Now that you mention that, I will probably make the floor door insulation removable and put some kind of vent in the floor for heating it in the winter.  I'm not as worried about warmer temperatures in the fall.  I know it won't be 35 F under there but I figure how warm could it really possibly get under my house in October?  Unfortunately, a "normal" root cellar is probably out of the question for us for two reasons, one is the bedrock being at depths varying from just a few inches to maybe 3 or 4 feet and second because of our high water table during the thaw, basically any hole in the ground would get flooded.  This is why I plan to dig the hole and fill it most of the way with gravel.  If we were to build an external root cellar, we would probably have to build it on grade in a dry spot and then put several tons of dirt on top of it basically creating a large mound..... as I said keeping it simple and cheap for now so this is not an option.  Thanks again for the input about keeping stuff from freezing.  Curious whereabouts are you in Northern WI? 
 
Mike Jay
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Location: Northern WI (zone 4)
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Sent you a PM...
 
Rebecca Norman
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Location: Ladakh, Indian Himalayas at 10,500 feet, zone 5
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I feel that /having an earthen floor and/or walls in a root cellar seems like it should be better for the roots than a sealed smooth thing like a fridge. I don't know if it's true, just how I feel.
 
Bryant RedHawk
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Location: Vilonia, Arkansas - Zone 7B/8A stoney, sandy loam soil pH 6.5
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Cold is only part of the root storage story which comes in three parts; temperature, humidity and breathability (air exchange).

There are lots of ways to do this right but far more ways to do it wrong.

Earthen floors covered in pea gravel are the standard for "true" root cellars, this is because if the humidity gets to low you sprinkle water on the gravel floor to increase the humidity over a longer period of time.
The vents (at least two, one up high and one down low) allow air flow to keep molds from getting a grasp on things, these have to be sized to the interior space of the cellar.
The cold air you want to stay above freezing but below 45 degrees as much as possible. Caves usually have an average temperature of 55-45 degrees for a base knowledge.

Of course you can go "artificial " and build one in a basement, when done right they work great.
there are a lot of methods available on MEN too.

Redhawk
 
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