Diy root cellar in N. AZ 1000ft water table

I question the practical utility of a root cellar in AZ. Gas station fuel tanks are typically buried about the same depth as your root cellar would be. At no time during the summer months is the gas cool coming out of the ground. Maybe you are far enough north to cool it down at night. I live in the Valley of the Sun.

Good luck! I salute your plan to be less dependent on outside influences.

Thanks.

I must be further north. My underground water tank provides very cold water. This gives me hope. Maybe the fuel tanks aren't cooler due to the surrounding cement/asphalt. That stuff holds heat like no tomorrow.

I'm sure you are correct. If your water is cool, there's no reason to think your root cellar won't be cool, too.

You are right, I live in the middle of the "asphalt jungle".

Not to pry, but where, generally are you, what's your elevation?

I live in Golden Valley at about 2700ft. The nearest ashpalt road is 1 mile away. Just have to deal with the baked hard soil.

The root cellar experts are in Elliston Newfoundland. http://www.rootcellars.com/ You can probably find a contact with structural engineering details by contacting folk in Elliston.

I have one comment about the use of pressure treated wood. Pressure treated with what? And why. It doesn't make sense to me, to use a toxic product to construct a food storage area. I realize you intend to store canned foods, so maybe there's no issue for that. However I assure you that no treated wood was ever used to construct root cellars that lasted a hundred years or more under our conditions (freeze and thaw). Could it be 'overkill'? Will these materials degas into the cellar atmosphere? Will they pollute the adjacent soil? What if you decide to grow and store potatoes down the road, in addition to your canning.. would you be comfortable with storing them in such a cellar? I wouldn't, and your kids might not either, if the cellar survives long enough for them to use it.

I have a root cellar attached to my home. The floor is dirt: the walls were poured concrete same as the house foundations. The roof and hatch for entry are in my unheated North side porch: the construction is 2X6 same as the rest of the house, with fiberglass insulation. The temperature in the cellar is cool and above freezing all year round. My folks have a similar cellar with a 2X4 "roof" exposed to the elements: the desired cellar temperature was always maintained under these conditions, but there is some rotting of the wood structure exposed to the elements. A shed type structure above ground is very typical of cellars and keeps them lasting under our environmental conditions: no treated wood required. More interesting versions such as in Elliston were built into the side of hills or completely earthed in over aboveground entrances. An above ground shed to enter your cellar would also moderate any temperature effects of the sun in Arizona.

Good luck with your project.

thanks for the info. I planned pressure treated due to the humid conditions of underground buildings. Haven't given a thought to possible outgassing. I've only used pressure treated posts for fences in the past. I'll have to do some research on the issue.

Again thx for the heads up.

When I was working as a roofing contractor we would occasionally waterproof the top of some poored cement underground service structures (complete with manhole cover) using what amounted to a built-up roof. These structures had 12 inches of backfill gravel on the sides which were treated with asphalt and a cushion.

On one occasion, a service structure was placed directly in line with natural drainage path and it flooded the pit. If it hadn't been for small hairline cracks that allowed the service module fill up with water, it would have floated right out of the hole. Consequently, the contractor had to figure some way to divert the water.

My point is this. Once the water penetrates to the level of the backfill gravel, it will be around for some time unless you also have a sump pump. With so little rainfall, it would seem that you could take enough precautions to make sure the water never gets that far down. On the other hand, it is better to consider how you will remove excess water than to try to build an underground submarine.

BTW, pressure treated lumber is generally treated with salt water in most places. It dosen't prevent rot, it just tastes bad to the usual lifeforms.

Kudo's Kujo and hi from Brunswick Oh. A familure saying here, "If I was you", with your intial investment I would increase the size for storage purpose and temporary housing or safe room. Well, ya know? Darrell D.

Good morning kujo. I commend you for your planning ahead; however, I have the following comments.

Years ago in another life, we did studies on underground temperatures in s. Nevada & s. AZ; at a depth of 36". Although somewhat lower in elevation than your 2700', and not as deep as your planned root cellar, the summer results were in the neighborhood of 90 to 100ºF.

A flat roof will tend to hold the rainwater. A sloped design will be better.

Treated wood is processed with arsenic. I don't think you should store food or habitate an area so treated.

Altho more expensive, I think concrete construction would be a better way to go, for underground installations.

A combined floor-foundation over a vapor barrier with rebar for the walls would be a good start.

Solid-poured walls would be the best, but more economical would be cinder block walls. If the latter, fully grout the walls with well designed rebar placement. Cover the exterior with tar to prevent moisture migration.

Design a steel-reinforced concrete roof, with a sloped top surface. Coat with tar. Voila!