New here. Root Cellar / Fire Shelter

Re wildfires. Maybe team up with some beavers ;-) https://www.facebook.com/CELPwater/photos/a.2117592371627200/5288856484500757/?__tn__=%2CO*F

This whole thread with fabulous, detailed photos & detailed information is exactly what I needed to read right now because we’re considering building a root cellar here on our North Carolina homestead. Very impressive root cellar/storage/safety shelter spaces! Beautiful design!
One issue here is a very high water table and we’re right on a very active creek. We have concerns that even on our highest ground we’ll hit water pretty quickly when digging the floor of a cellar. Has anyone here built a root cellar under these conditions??? We are mostly wanting our structure to be for food storage - squashes & canning & bulk foods.
Again, very impressed with these cellars you’ve built!

Gaurī Rasp wrote:This whole thread with fabulous, detailed photos & detailed information is exactly what I needed to read right now because we’re considering building a root cellar here on our North Carolina homestead. Very impressive root cellar/storage/safety shelter spaces! Beautiful design!
One issue here is a very high water table and we’re right on a very active creek. We have concerns that even on our highest ground we’ll hit water pretty quickly when digging the floor of a cellar. Has anyone here built a root cellar under these conditions??? We are mostly wanting our structure to be for food storage - squashes & canning & bulk foods.
Again, very impressed with these cellars you’ve built!

Squash likes to be stored in dry temps at room temperature in my experience, so, while that wasn't your question, I wouldn't store it in a root cellar.

As far as the high water table, the only answer I know to the question is to build it above ground and then pile earth over it if that will work in your situation.

Gaurī Rasp wrote: Has anyone here built a root cellar under these conditions???

We built on a high water table. Here's a link to my post:  https://permies.com/t/165961/Root-Cellar-Fire-Shelter#1302551

On the burnable roof thing, there are products that can be sprayed on the roof, at the last minute, that have gotten homes through fires when others didn't make it.  

If memory serves, the product is a bit like the material used in baby diapers, a gel, and hold moisture long enough to get the roof through a flash, or to render and ember harmless.

Shannon Snow wrote:Thekla McDaniels, . . . .

Robert Marsh, Our house roof, and now the shelter overhang are composite shingle with the highest fire rating available. We have roof sprinklers which we test periodically. In fact, we had a big fire get close last week and were able to go through our whole plan. We had 4 adults, a 4yo, 3 big dogs and a puppy. It was an adventure for sure, but we were able to run through everything without panic and our plan is solid. We didn't need to use the scuba air, and the 3 hours sheltering went fast. (nobody had to pee, but we were prepared for that too) We did this because our only egress was cut off by fire. Otherwise we would have certainly evacuated.
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I keep dreaming of a root cellar and it may come true some day. I am very impressed with all the root cellars I see on this thread. In Wisconsin, we can get quite a bit of snow, so any door shy of vertical and we would be hard pressed to open it to go in or out. Building it like a basement must be quite costly. Has anyone had experience sinking a couple of septic tanks and then making them connect?
I was thinking that although the space would be somewhat smaller, having 2 or 3 septic tanks connecting would be better for keeping apples and potatoes separate, for example.
At this point, it remains a dream: Hubby doesn't believe that we need one, so if it happens, it will be on my dime and my efforts only.
I must say that all your wonderful pictures and your ideas really make a lot of sense. Thank you very much and keep them coming!

Cécile Stelzer Johnson wrote:I keep dreaming of a root cellar and it may come true some day. I am very impressed with all the root cellars I see on this thread. In Wisconsin, we can get quite a bit of snow, so any door shy of vertical and we would be hard pressed to open it to go in or out. Building it like a basement must be quite costly. Has anyone had experience sinking a couple of septic tanks and then making them connect?
I was thinking that although the space would be somewhat smaller, having 2 or 3 septic tanks connecting would be better for keeping apples and potatoes separate, for example.

There is a great book authored by Mike & Nancy Bubel, Root Cellaring: Natural Cold Storage of Fruits & Vegetables that you might want to check out. The paperback edition on Amazon lists for only $15.29, yet is a GOLD MINE of information on Root Cellars.

The very old Root Cellars were usually one room in size. The idea was to preserve roots and veggies in a "controlled" climate (no ice & snow)! The real old cellars actually have a high humidity, low temps, yet could keep a variety of foods at somewhat temps. And they usually seem to have very fresh air when entered. Usually the humidity and freshness comes from the soil. And usually, these set away from the house as they were half or more below ground and the remainder above the normal level of ground but with earth thrown across the top in a fairly thick layer (up to 3 ft. or more).

Cement or Block Root Cellars are O.K., but have the problems of controlling the humidity and ventilation in and out. That is where the book really excels in explaining how and why you need to adhere to some specific necessities to have a great root cellar. It also explains the necessities of having separate 'rooms' in the cellar.

As for your cold winters and deep snot you might think about having TWO DOORS for entry. The steps down to the cellar would end at a solid vertical entry door. The other door would be on horizontal and hinged across the top of the steps to keep rain and snow out. Just my idea of not having to shovel snow or siphon water out of the cellar.

Read the book so that you gain some knowledge and then advertise to see if there are LOCAL Root Cellars that you might be able to visit for both viewing the root cellar and talking to the people who use it!

Ah, I wish I could build one also.   :-)

Jesse Glessner wrote:

and then advertise to see if there are LOCAL Root Cellars that you might be able to visit for both viewing the root cellar and talking to the people who use it!

Many cities do annual garden tours featuring residents' private gardens. Meh. I'd pay good money to check out a variety of root cellars, though. The older the better. A visit to this town would be fantastic:

https://www.atlasobscura.com/articles/root-cellar

I’m no expert on fire shelter, but here’s some physics:

1. Air in an inground cellar will be much cooler than outside air. Vents/doors all open to ground level above. Cool air wants to sink and will stay in cellar. Warm/hot air wants to rise and will stay above outside. I believe the risk of toxic gases entering cellar from ground level will be minimal. Limiting factor will volume of air in shelter.

2. You can reduce duration of shelter time by reducing fuel (large trees, buildings) in the immediate area. Small fuel load will burn out quickly and allow you to come out fairly soon.

Our current root cellar was built as an experiment in the fall of 2019 and proved to be an excellent way to store food long-term in our climate which routinely dips to -40 in the winter.  In essence our root cellar is a buried 8'x14' insulated aluminum box taken off an old refrigerator truck which then had several traditional root cellar modifications made to it. Total actual cost for this project was less than $500 CAD. I posted the details of this build with lots of construction pictures and a long list of learnings on another permies thread - "refrigerator  that doesn't use power" (https://permies.com/t/40/132501/Refrigerator-doesn-power-build#1393637).

We are now in the process of constructing another 8'x14' root cellar based on one major lesson learned from our first root cellar: as we age, we don't want to have to venture outside in the winter to access our veggies. So our new root cellar will be accessible directly from the basement of our new addition.

All of the block walls of both the addition and root cellar are being constructed of Nexcem (an NON-styrofoam ICF block which is fireproof; vermin, termite and insect proof; does not support fungus growth; highly energy efficient [up to R28]; constructed of 80% recycled material including clean softwood aggregates, does not contain or emit any toxic elements; and is lightweight and yet very durable to build with). Yet despite all these desirable traits, Nexcem still may have to be modified for a root cellar application as it is also hygroscopic. This vapor regulator trait typically keeps indoor relative humidity levels at healthy/comfortable levels (not exceeding 70%) - which is highly desirable for living quarters but not ideal for a root cellar. Thus we may find that we will need to seal the blocks inside the root cellar to prevent them from vapor regulating. We plan to use 1/2 the addition's basement (which will have a cement floor) as a dry cool storage, as <70% humidity is great for onions, garlic, and canned goods.

Hi Al, thanks for sharing this new to me material “nexcem”.

What a pity it is water loving!

I’m always cautious, even suspicious of any attempts to keep moisture out.  A very smart engineer and builder once told me that sealing water out very often works backwards, in that trifling amounts of moisture will “always” find their way in…. and accumulate, if for no other reason than moving from higher concentrations to lower.  And the attempts to seal the moisture out will also prevent the moisture from leaving.

Hopefully this phenomenon does not apply to your situation/ plans.  

I mention it mostly because I was so startled by it, that I assume others may also not be aware of it as an important consideration.

Your root cellar sounds wonderful!  Good luck on the next one!  Not having to go out through the snow and storms will be a real improvement for you.

Thekla,
Nexcem neither keeps water out nor keeps it in. It works similarly to how hempcrete works; it both absorbs and releases humidity to keep the air's humidity within a certain range. The "technology" is centuries old as many building in Europe are built with hempcrete. However Nexcem differs significantly from traditional hempcrete builds in that its "hempcrete-like" part (made of wood fiber and Portland cement) is an ICF block. The outside half of its central cavity of the block has Roxul insulation and the inside 1/2 of the central cavity is where the cement is poured into. These block walls are reinforced both vertically and horizontally with fiberglass rebar - which has 2x the strength of metal rebar. With insulation to the outside and thermal mass to the inside that's what makes it easy to maintain climatic conditions within a structure. In the root cellar we'll have to see how we can override Nexcem's humidity modulation as root cellars should have their humidity above 90%. Conversely our basement dry storage area will greatly profit by this humidity modulation capability.

FYI If you go on the Nexcem website you can see lots of great research done by independent agencies like University of Toronto and University of Waterloo.

I believe your area may have had a severe bushfire recently, how did you go with your preparations?