New here. Root Cellar / Fire Shelter

It took a year and a half, but we built a root cellar / fire shelter. No one in our neighborhood has done this, so we are the pioneers. I'm looking for a place to share what we learned, and to ask questions. Have I arrived?

I've attached a couple of photos of the outside. First shows the temporary outer door. The inner door is a 3-hour fire door. We are in the process of building the roof part to cover the area from the house pantry door to over the root cellar opening.

Your root cellar makes my root cellar look like an idiot. Very, very nice work.

I take that as a compliment. Wait until you see the inside. Also, it has a stand alone solar panel that charges a battery so we can have lights. Recently purchased are 2 scuba tanks for air in case of sheltering during wildfire (last resort of course).
How did you build your root cellar?

Our root cellar is built with earthbags, so it won't likely survive the kind of bombardment that yours will. We began our build in 2018 and still have final touches to complete. Our biggest challenge was the high water table and our inability to dig it into the ground. We hauled in many dumptruck loads of gravel to berm up around the cellar and need about one more to complete it. We're also installing styrofoam and polyethylene to act as an insulated umbrella that will hopefully smooth out the seasonal temperature fluctuations. We have hit 0degC as a low during our two winters of usage but in the summer we're seeing 13degC, so we need to keep that down in order to use it as our refrigerator.

The photo is before we put our yurt on top, creating a basement/root cellar with trapdoor access.

I'd think these make great root cellars, from a DIY viewpoint.

I'm not sure at all of their effectiveness as a (wild)fire shelter, from a "lack of oxygen" viewpoint, even with SCBA's (with testing, maintenance and such). I would research how much O2 would have been available at ground level and for how long was it not available, during a big one.

Are you only "one-way in, one-way out", along a few miles of road? Perhaps become a ham operator, or otherwise monitor the airwaves for what's coming at you. Become a volunteer FFT in your area, and get their radios. Cut in another escape route.

Historically, such as in the massive fires in Wisconsin in the late 1800's, entire forests went up, along with towns/communities, and whole families suffocated in their cellars & basements. Fire at that scale might be better avoided altogether ... and advance knowledge of what's coming at you is better from a prevention vs cure viewpoint.

Perhaps a lesson for all of us, to get on the air with radios somehow ...

Jt Lamb wrote:

Historically, such as in the massive fires in Wisconsin in the late 1800's, entire forests went up, along with towns/communities, and whole families suffocated in their cellars & basements. Fire at that scale might be better avoided altogether ... and advance knowledge of what's coming at you is better from a prevention vs cure viewpoint.

The 1871 Peshtigo Fire(s)! I'd been researching that cluster of fires over the winter and found the stories terrifyingly bizarre. I found a book call "Embers of October" by Robert W. Wells that was all about the fires. Crazy story. I don't think it's a coincidence that they coincided with the Great Chicago Fire.

I think anyone that is adequately prepped for a disaster like that one is ready for just about anything.

https://thumbwind.com/2018/04/23/great-lakes-fire-1871/

Regarding the original post, I know nothing about forest fires.  I would be concerned about both oxygen and building a giant oven for myself.   But, I do see great value in what you have done. First there is value in the root cellar aspect. Then, there is the fact that you have constructed an area that is more safe for equipment and other property you cannot remove from your site. Finally, if you cannot evacuate, you have created a safer place for your family.  I am impressed.

John F Dean wrote:I know nothing about forest fires.  I would be concerned about both oxygen and building a giant oven for myself.   But, I do see great value in what you have done. First there is value in the root cellar aspect. Then, there is the fact that you have constructed an area that is more safe for equipment and other property you cannot remove from your site. Finally, if you cannot evacuate, you have created a safer place for your family.  I am impressed.

For the sake of clarity, I'd like to state that, in my case, I was only building a root cellar for food storage purposes. Any resemblance to a practical (or impractical) emergency shelter is purely incidental. If faced with an actual emergency, my plan of action is to run around shrieking like a little girl and frantically gathering up items to flee with that have no life-saving purpose.

Hi Michael,

You are approaching a great point. In psychology there us a saying that “ the best predictor of future behavior is past behavior.”  I live in a forested region that has good rainfall and has never seen significant forest fires.   Recent events in the west indicate that I may not be able to rely on past climate behavior.   I need to revise my evacuation planning.

John F Dean wrote:Hi Michael,

You are approaching a great point. In psychology there us a saying that “ the best predictor of future behavior is past behavior.”  I live in a forested region that has good rainfall and has never seen significant forest fires.   Recent events in the west indicate that I may not be able to rely on past climate behavior.   I need to revise my evacuation planning.

Our town actually had a fire 5 years ago that triggered a partial evacuation. We experienced first hand what happens when you have to pack up and flee, knowing that you might lose everything you leave behind. Luckily for us, our town is the regional forest fire base, so we had water bombers available to quickly put out the fires that were being quickly spread by howling winds.
Strategically, we are in a good location on the northeast edge of town, because we rarely get east winds. Any fire is likely going to approach the town before us, so we'll likely be spared by the efforts to save it.
As an interesting side note, the only home damaged (slightly) by that fire was owned by someone that had been living and working in Fort MacMurray, Alberta. That town had been mostly destroyed by a fire just weeks earlier and the owner lost everything there. Even more interestingly, another Fort Mac resident that lost their home had decided to travel back to their ancestral home on the East Coast, and when they arrived, that home was on fire.
Fire has a weird sense of humour.

Looking at these pictures I find it interesting how much less dirt is used in these than here.  Because our frost line goes down at least 4 feet with nearly 5 some years working root cellars here the goal is at least 4 feet and ideally 4 to 6 feet.  If less dirt is used then added insulation is used instead.  One root cellar had a layer of straw bales just over the wood of the roof and about 2 feet of dirt over that.  It sort of worked.  If you put glass jars down on the floor they didn't freeze.  But it always smell of mice and mold.  The good cellar had about 6 feet of dirt to the thin spots and about 8 feet over all.  Its temperature only moved a bit.  Basically it just sat there at nearly constant temp. it had 3 doors.  Entry, hanging canvas and the cellar door.  Having dealt with flat to sloped doors the ideal would be a straight up and down door with a ledge/step going up at least one before going down so snow melt didn't get in and so shoveling the door off was minimal effort.

Having spent many years hauling stuff up and down steep steps if possible I would build for a gentler slope or even ideally for a level walk in or even a very slight up hill walk in.  The good cellar was built into the side of a steep hill and it only dropped about a foot going in.  It had a french drain line with a valve so you opened the inner door and stepped in and turned the valve on and the last about foot of water drained out with no pumping.

Anyone using these for fire shelter needs to remember CO2 at fairly low levels can kill you even if you have oxygen.

C. Letellier wrote:...it had 3 doors.  Entry, hanging canvas and the cellar door.  Having dealt with flat to sloped doors the ideal would be a straight up and down door with a ledge/step going up at least one before going down so snow melt didn't get in and so shoveling the door off was minimal effort.

I am having trouble imagining this. Any chance you have some pictures laying about?

I, too, am having trouble visualizing this. I would love to see pictures or diagrams. We are planning to start a root cellar next spring, and deal with extreme cold and heavy snow (South Central, Alaska.)  We do intend to dig it into a hill.

"...it had 3 doors.  Entry, hanging canvas and the cellar door.  Having dealt with flat to sloped doors the ideal would be a straight up and down door with a ledge/step going up at least one before going down so snow melt didn't get in and so shoveling the door off was minimal effort."

Vickey in Alaska

The roof part is coming along. It's painstaking to mill the wood, but we're on track to finish it before snow. I'm still learning to navigate this site and someone mentioned CO2. We have a monoxide meter in the shelter, 2 big new SCUBA air tanks, 2 - O2 sat meters, and a Diazepam for my dear claustrophobic husband. I also have duct tape in case the benzo isn't enough. ALSO -- this shelter is a last resort in case we cannot evacuate. We had a couple of weeks of 100F+ days, and now the root cellar is hovering around 66F, so I took out all the butter and will can that tomorrow.

Hello JT. Yes, HAM is on the list. First we have to upgrade our solar. (in the works) We have a police/fire scanner that really helps, and yes, we are one way in and one way out. When we moved here 20 years ago, big fire wasn't really on the radar. We've spent that time getting more fire safe by managing the forest properly, roof sprinklers, 3000gal holding tank, fire hydrant, etc., and yes, we volunteer for the local fire dept. I'm an EMT. I don't want my forever home to burn, and I want either a way out and off the mountain, or a safe(ish) place to hunker down.

Nice looking root cellar you have built! It looks like the roof is made of wooden timbers that span the concrete walls, I am wondering why you opted not to pour a concrete lid for it? I built a cellar with very much the same design, only a little smaller. Mine is only like 6 feet wide, so with a 4" slab with LOTS of rebar, I piled about 3 feet of dirt on top.

I too have been thinking a lot about cellars as fire shelters. One thing I would like to point out: you should make some provision for what you are going to do if a tree falls on that outer hatch. Electric chainsaw, maybe? In a pinch, you could chop away at your ceiling with an axe, maybe?

Anyway, on the topic of fresh air in confined spaces; I have done some reading. The general consensus seems to be that CO2 concentrations will kill you faster than lack of oxygen. From what I gather, this guy got most of the details about right:
https://www.physicsforums.com/threads/how-long-can-one-live-in-a-sealed-room.685796/
He uses 30,000 ppm as the lethal cut-off, but i found some other sources that said that this is likely too low. It would probably take closer to 50,000 or 5% CO2 by volume to cause incapacitation in about half an hour. In general, his numbers check out, and can be simplified to this: every 10-15 cu ft of air will last you about an hour. Counting your blocks, it looks like you have an 8'x12' space with 8' ceilings - so 768 cu ft. Using a fairly conservative 15 cu ft/hr, one adult should be able to survive sealed up in there for over 50 hours. 2 people could easily go a whole day. This volume will decrease as you store stuff in there, so dont forget to take that into account. I have never experienced a forest fire firsthand, but I understand that they burn through an area pretty fast. I suspect you should have no problem at all sheltering in there for several hours. I think if you could seal off the air inlets from the inside you should probably be fine.

Another thing worth mentioning is about fires "consuming all the oxygen." From what I have read, fires in solid materials need a certain oxygen content to even burn. If the air becomes too depleted of oxygen, the fire will go out. This might be different for gaseous fuels, so dont store any gasoline in your shelter! It sounds to me like a human can survive on less oxygen than a wildfire can, but having a way to seal yourself off from the fire seems like the best bet. There is also going to be an insane amount of smoke, so really get after all the cracks with some duct tape. As for the scuba tanks, they are going to buy you a few hours, at best, right? A more compact method would be to store ordinary welding oxygen. An 80 cu ft tank costs like 20 bucks to fill, and should be enough for 1 person for 4+ days. You would then need to also scrub CO2 out of your air, but CO2 scrubbers can be put together out of Ca(OH)2 with a trace of NaOH on it. You can buy 50lb bags of slaked lime at home depot for 12 bucks. I forget how much CO2 that would remove, but it was a lot. Youd need a fan, and some sort of container to hold the little clumps of co2 adsorbent. Youd also need to be a little careful here about raising the O2 content too high. I would not suggest you try that without a dependable O2 meter handy.

Anyhow, I am chipping away at a new cellar project. I will have to put together a post about it when it gets a little farther along.

Well hello Carl. Thank you for the informative post. To answer some of you questions, the 2 vents have airtight caps if needed. Fire door is all but air tight, and a roll of duct tape is already in the shelter to seal it if necessary. A section of the cinder blocks has no rebar, and there is a sledge hammer in the event the door becomes blocked. Leave it to a severely claustrophobic to think of these things (my husband). We got the scuba tanks because we have 3 husky dogs who vehemently refuse to wear an oxygen mask. The roof is milled wood because we can mill our own wood from our own trees with an Alaskan chain saw mill for free, and concrete is expensive. We spent our concrete $ doing the floor, stairs, and filling the cinder blocks.

I am delighted you counted the cinder blocks and estimated the sq. footage. We concur. There are food stores that take up some space along the sides, but doing the air x time x space math, we came up with different numbers every time we calculated, but it doesn't matter. We will only use the cellar for a fire shelter if there is absolutely no other option.

Thanks for the CO link. We will definitely check it out. I have 2 O2 sensors and a monoxide meter in the shelter.

We live just west of Paradise California and have seen how big and fast and ferocious a forest fire can be. Presently we have a fire to the north and one to the south. Smoke has been really bad for a long time. It's harrowing, but being as pro-active as possible gives us a sense of control even if it is in reality no control.

I would post a photo of the inside, but I haven't figured out how to attach in a reply. Would love to see photos of your cellar.

Photos of inside.

I love the root cellars shown here. A couple not far from us built an earthbag spring house that they also use for cold storage. That was practice for building their earthbag dome home. Our water table is also very high here, sometimes above ground eek! We are on flat land at the base of the mountains so we would need to build it above ground and then berm over it. A lot of work that I'm not strong enough to do. I would love to have somewhere out of the house to store canned goods and all the canning supplies that you really don't need every day. Shannon, I love the inside of your root cellar and noted that you store your pressure canner there. That makes so much sense to me. All those empty canning jars are also a pain to store.

Hello Josephine.
I'm wondering if an above ground cold storage is feasible. Maybe think of a TuffShed sort of building and then insulate the crap out of it. ?  Or just an un-insulated shed for canning supplies. We started this project as something to keep us busy during Covid lockdown. A year and a half later, still lockdown, still no work, BUT the cellar is coming along nicely.

I know it looks like I'm a prepper or a hoarder, but the fact is the grocery store is a 52 mile round trip, and driving the river grade isn't something I want to do very often. I call it, "going to the store" when I get something out of the root cellar. I started making a peach cobbler today with some peaches I got for a potato trade. The peaches were awful and unusable. Thankfully, I didn't waste the flour, butter, sugar and milk already mixed in the bowl because I had a can of peaches in the root cellar. No way would I drive 52 miles for a can of peaches.  

WOW! That is a stellar cellar!  About the only thing I would have done, is maybe make it bigger.
Will that foam panel insulation stay in contact with the steel fire door? Or will it be replaced by heavy duty aluminum foil between the steel door & a forever insulation, like Roxul?
Thing is, plastic foam + heat from fire = melted goo.  
Roxul is guaranteed fireproof, critters dislike it, & it won’t mold.
Good to wrap the blocks with a few layers of vapor barrier, before backfilling, to help keep it dry. Great to earth-cover it with at least a foot or more of dirt & fire resistant ground cover, or rocks.
Love that you put a block basement under your yurt!  It should help keep the yurt at more tolerable temps longer without having to heat as much in winter.
Now, need to maybe make the floor of the yurt fireproof, so it can help protect what’s in that downstairs.
Have you set up a faraday cage to house your electronic gadgets?  
When running Romex for electrical, have you twisted each wire run, about 1 twist per yard of wire? (Helps reduce overflow electrosmog emitted from wiring).
All stuff to consider. I added the thing about faraday cages & wiring, because things like that can help protect electronics from EMP bursts…like the mega-solar flairs that recur, or, an enemy blowing one over the country. …if either happens, all electrical become bricks…except the protected ones.  It also makes the living spaces healthier.

Oh..almost forgot…
In earth covered cellars, that will need to close tight against wildfire…they need venting that has filters to prevent cinders or smoke choking the sheltered survivors.  An inlet pipe run underground about 2’ deep, runs horizontal for at least 20’, then has a bend to come above grade, then a U-cap that allows air but not rain.  Same for outlet pipe. Can put inlet pipe low to ground, & outlet pipe high on a wall…that way, air can convect without an electric fan if necessary.  All pipe sections within 1’ of ground surface/grade, must be metal to survive wildfires.  The cap ends can have a rock pyre around them as more protection & camouflage.

Not Josephine, but a bit of experience..
Above ground cellars must be very heavily insulated & buried or bermed, with the floor open to ground to get the earth’s temp to help cool the interior.
Easier to dig proper cellar, I think?  
At one time, had bot a 40’ freezer-load container. It was claimed to have R-30 insulation, but the walls could only have had about R-13 at most, because it was only 2” thick. But the whole box was insulated.  
It still had the tracks on the floor…perfect to lay Pex tubing for geothermal/solar heat & cooling.   I planned to also lay loops on the ceiling.  
Tubing would connect to rooftop loops of agricultural tubing & polycarbonate coverings for solar heating.  Then, another bunch of loops would get buried 6’ deep in the ground, with insulation over it, before backfilling.  With proper pump, switching valves & holding tank, temp inside could stay comfy all year, just about, with very little other heating fuel.  And that one was above ground in SW Washington.
But any built above ground would not survive wildfires, unless it was deeply bermed/buried, with filtered venting.

Shannon that's an awesome root cellar!

The only suggestion I hope you'll think about is adding a bar across the front of each shelf to help keep the jars on in an earthquake?  I would expect that pretty much anywhere in Northern California would be considered at some risk. If it were me, I'd bolt it through, so if you want to clean or do a big re-arranging job, you could remove them temporarily. Similarly, I'm assuming you have put some water in there?  Even a few buckets of water on the ground that you re-fresh once a year, would be nice back-up.

Hi Jay. Thanks for the thoughtful advice.

I do have 4 gallons of water in the back under one of the shelves. We moved here partially to get away from the Bay Area earthquakes. We've had a few since moving here, but they're smallish...however, you never know when a big one will hit. Our last one was a 5.2 cobblestone rumbler. Nothing fell.

We secured the scuba tanks to the wall with earthquake in mind, but I didn't think of the cases of canned goods. I will go and rearrange stuff tomorrow and also ask my husband to make a wooden bar for at least one of the shelves. Store bought jelly is on a high shelf. What a mess that would make.

I'm sure appreciative of yours and everyone's thoughts and advice. I don't know what I don't know, but am willing to learn.

Putting earthquake rails in front of each shelf is a very good pointer…even anywhere else..because earthquakes can happen anywhere…really.
Can be as simple as screwing 1 end of a 1x2 to one side of a shelf, & latching it at the other end to make it easy to drop it for cleaning & organizing. Even a strong bungee strap hooked across the fronts of shelves.
Good you have potable water in there…a wildfire could keep you in there for many hours.
You should maybe have a bucket potty, or camp potty in there, too. (What goes in must come out!)
& of course, emergency lights, & tools for dealing with excavating your way out in case debris fell over the door or pathways.
Will you be prepping the downstairs (basement) of your yurt to also be survivable space?
Insulating the yurt with Roxul (fireproof)?  Maybe beefing up exterior with metal cladding?  
We thought about doing that with ours, years ago. And thought about replacing yurt with a Pacific dome, & gradually beefing that up with Roxul & metal cladding.  There are few roofers capable of metal-roofing a yurt roof…it’s tricky, but, would be a forever roof, & resist fires.…it’s amazing how fast time passes & new covers are needed.  
Did the yurt company advise you to place an upright post under the outer end of each rafter?  
Our 30’ yurt really danced in the wind on our hill…we only put a couple spirit poles under the top ring as extra support, yet it did very well..in high winds, those lifted up and down from the concrete ring on the floor—only hooked them to the top ring to allow movement & still support.  It would have been a good thing to have put the supports under each rafter end, too.
Pacific domes are geodesic frame, so, those don’t dance in high winds..only the tent cover flaps about.
In a forested area, everything is so peaceful for long time…until suddenly something like a wildfire threatens. So, also try to keep the area around your yurt cleared of fire fodder, at least a 50’ radius or more.  If your site is a hill, fires will blow upward faster from below, so widen that cleared area, more.  
Would love to see more pics of your progress!  It sounds & looks wonderful!

Shannon, we currently use one of our back bedrooms as our "pantry." I did buy a huge shed from a closed garden center that I will probably use for the canning supplies. It came full of her unsold garden supplies which I have been selling off. Even with selling almost $5,000 worth of goods, it is still over 1/2 full! I need to empty it before I can move it off the trailer it came on and lower it down to ground level. It's 13 x 32 so truly huge. Because her husband is an electrician it is wired with lights, plugs, and an exhaust fan. I just have to plug it in with a strong extension cord. I'm going to put right next to an electrical plug I had installed on my power post.  

Josephine Howland wrote:

It's 13 x 32 so truly huge. Because her husband is an electrician it is wired with lights, plugs, and an exhaust fan. I just have to plug it in with a strong extension cord. I'm going to put right next to an electrical plug I had installed on my power post.

Wow, at that size, I immediately pictured an outdoor canning kitchen -  you can tell what's in *my* dreams!

That is a huge bldg.! (Wishing for similar!). All kinds of potential.   That thing is bigger than both of our kitchen areas, here, put together!  What a boon!
Oh, there is one way to low-tech help cool an above-ground, well-insulated building (think: R-30 in walls & ceiling, at minimum).
An old guy had made a fridge/freezer from an old, hollow birch tree trunk.  
He made 2 doors in it, & separated the compartments. Where he placed the trunk was over a 6’ deep hole in the ground. A flex tube carried air from the bottom of the hole, up to the top of the top compartment, which overflowed via a vent to the lower compartment, & from there, air dropped down into the hole again.
If it ran all the time, it would keep getting colder & colder, from recirculating the chilled air. So, he included a thermostat to help automatically regulate it.  It could alternately be done using a manual timer pin-set to run for a limited time several times over each 24 hour cycle. Fiddly to set, but, low tech easy (we do that, now, to use a small chest freezer as a fridge, run off a Goal Zero battery box).
DC computer fans + a thermoelectric fin gadget ran from a small solar panel in sun. Those can only chill air about 30F lower from ambient air temp…so, getting the air from 6’ in the earth, means his freezer could keep ice cream fairly hard-frozen, because the thermoelectric thing only had to chill down from about 55F, meaning the freezer could get down to about 25F.  
If his site is still up, https://www.museumsusa.org/museums/info/14783.  
He died, but someone is caretaking his legacy…full of cool info.
Beefing up the size & number of thermoelectric units & fans, can chill lower. There are YouTube’s demonstrating this.
Insulating the box more, helps maintain the cold better….a lot.

Hello Chi.
I think you may be mixing up my post with the yurt post. I do not have a yurt, but his is coon nonetheless.
I'll post progress of the permanent outer door and the roof overhang in a few days.

I don’t think so…the post was about how to use the newly acquired building.
And someone, I thot, asked if they could achieve an above-ground cool room, like a root cellar…
…but maybe I got 2 posts replies rolled into one post.  
Been working on stuff past my limits. A bit thick-headed tired.  
Today’s work was trying to edit the exuberant squash volunteers out back; HUUUGE vines, small pumpkins; reminds me of the plant in Little Shoppe of Horrors, (FEeeed me, Seymour!), & moving some plants around, etc.

It seems our learning curve is vertical, but we took our licks and are making things right. All the books said a root cellar needed to be 90% humidity. Okay. NOT okay. It's drippy wet in there and the wood is going to rot. We took out anything that needed high humidity, ordered a dehumidifier, and are going to be okay with the root cellar being warmer than the standard 55F, and we're shooting for 30% or less humidity.

I researched the difference between CO2 (carbon dioxide) and CO (carbon monoxide) and will remove the CO meter from the cellar. Having two O2 (oxygen) sensors will be enough.

The roof part is coming along nicely. Photo attached. The outer door is temporary and we now have the materials to make the permanent one.

Lots of advice, ideas, conversation.

I did not see any reference to gas exchange with the soil.

When I was on a USFS fire crew, (mid 1970s) we wore fire shelters on our belts, never wanted to use them, and I never faced that situation.

What we were taught was to scrape a little patch of soil clear of duff and pine needles for our faces.  The fire would move past, but in the soil itself there would be adequate O2.

I just wonder if tunnels into the soil would provide oxygen, and disperse some of the CO2.  Maybe a slope to the air exchange tunnel, or have a loop so that air could be moved through with a fan as needed.

Kind of like the “geothermal” heating and cooling systems that rely on a sub grade heat exchange tunnels/tubes.

Just an idea for consideration and discussion which may or may not have any value.

FYI for ideas....

We keep a 4' crowbar and hammer in our's (vs elec. chair saw.... lol)

I read your plan is to evacuate if possible, if not then use the root cellar as emergency back up. The less fuel that can burn close the better ?

The next time you need to re-shingle the house, metal roof ?

I know siding should be fire proof too, ideally metal or asbestos or masonry....  we compromised  with 1" solid oak (pretty good fire rating) trying to keep all trees at least 50' from the house, and keeping a lawn (yes, lawn... green growing short grass) that we 'will' (soon) keep well irrigated....

I don’t know where you are, Robert, but there’s a perennial plant being used in the western US as a fire break, maybe planting it in the fire breaks because it’s more effective at stopping or slowing a moving ground fire.



It’s called Immigrant Kochia.  It’s a low growing shrub.  Great Basin seed has a website where you can read about the plant, and what it needs as far as growing conditions, and fact check me(!).  It grows in arid conditions, holds water in its “leaves”, and provides high quality nutrient dense winter feed for goats, sheep, maybe cattle, deer and maybe other wildlife.

I would definitely recommend a HEPA air filtration system if you are expecting to use it during a fire. Also would be good as a prepper's bunker.

Thekla McDaniels, Good thoughts on the gas exchange. We have 2 vents in the inner fire door and 1 vent at the far end of the shelter with a little fan blowing out. If we need to shelter, we have caps for the vents, and duct tape for around the seal of the door + 2 scuba tanks for oxygen. Best estimates are we would need to shelter up to 3 hours in case of wildfire that takes out everything.

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.

Meadow Cern, we have though about the HEPA filtration, but after last week's run-through, we decided we don't need it. It takes up space, and while sheltering, we are on internal battery. Would rather have the lights.

Oh, and some fantastic news: for the past 20 years, we have been working on our land to make it more fire safe. The property owners for the land that abuts ours has done nothing. It gave me anxiety. Well, last month they brought in a team with a masticater and did their entire property! All the big trees were left, the dead ones were taken down, and all the small trees and tan oak got masticated. It looks great. I am the head of the Firewise Community here and they sent me a sign.

For anyone thinking about building a ROOT CELLAR you should read all you can about the process. One of the major things that people don't think about is that ROOT CELLARS were just that in times past.

Root Cellars stayed cool, and moist, because of being either mostly under-ground or covered with a thick layer of earth if any part of it was above ground. There were usually rock walls, but earth floors. And humidity came through the loosely laid rocks and the floor.

IF you're doing a modern version of a root cellar you really need to incorporate those same features into your new unit. And, you might consider TWO rooms to do that. One room would be for storage of canned foods and other edibles, plus equipment necessary if you're using it as an Emergency Shelter. Of course you will need venting both IN and OUT. But, the second room needs the same PLUS a humidifier and possibly a small refrigeration unit to maintain a temperature of around 38 to 42 degrees to keep your ROOT VEGETABLES through to the next Spring. And keeping those veggies nice and fresh may also require some special shelving or storage bins. NOTHING other than your Root Vegetables or other food crops you are trying to preserve for freshness should be allowed in this room!!

Just remember that 'FRESH' veggies in the middle of winter are almost as good as fresh veggies standing in the middle of your garden in the Summer/Fall times.

A great book about Root Cellaring is titled, "Root Cellaring: Natural Cold Storage of Fruits & Vegetables", by Mike and Nancy Bubel, Storey Publishing, 1991.

Chi Monger wrote:
And someone, I thot, asked if they could achieve an above-ground cool room, like a root cellar…

What is the general temperature range of a root cellar - and does an underground room somewhat replace a refrigerator without all the energy requirements?

Luke Bryan wrote:

Chi Monger wrote:
And someone, I thot, asked if they could achieve an above-ground cool room, like a root cellar…

What is the general temperature range of a root cellar - and does an underground room somewhat replace a refrigerator without all the energy requirements?

No, it does not replace a refrigerator..  but both supplements and provides a place for bulk storage that while not cool enough for refrigeration is cool enough for root crops (ideally with a dirt floor to keep humidity UP) OR canned / bulk foods depending on how it is designed.

Look up your steady state ground temperature where you live (usually 6' down) and that is THE COOLEST the cellar can be. The better built, the closer to that temp.

We are in SW Missouri: I just read that 1/3 of the Ozarks used to burn every year... (in the Conservation mag..), while wildfires of any size are now rare here... and some of the family think I kinda nuts for as much fire preparation as I have done (with a little left to do), even a small fire if it's close to you can be a disaster.....

Our cellar is a walk in from inside the lowest level of the house (you don't have to run outside, it's designed as a tornado shelter as well as fire shelter), with double doors; the double thickness insulated steel door opens inward, the light weight outer door opens outward (so we could easily break through it if needed). The door frame is 1/4" x 4" steel, welded to the rebar in the concrete walls. It's a big pantry (concrete floor, not enough humidity for good root crop storage, we don't keep more than a month or two of potatoes etc. there) so useful space. Roof is an arch of poured concrete with rebar on 6" centers then 2' of dirt in the center so deeper toward the walls...   it's flat in the yard and you would not know it's there.   Water, 12v power from the batteries as well as 110, floor drain, air intake and air exhaust.