Help Building a Coldroom

[take 1]

I have an unfinished basement. It never gets any warmer than 75 degrees down there in the summer.

So, I thought it might be a good idea to build a coldroom to store food preps and to get a lower and more consistant temperature to maximize the shelf life of some of this food (dehydrated, vacuum sealed etc.) somewhere below 60 degrees would be better.

Does anyone have any ideas they could share? eg: insullation, venting, shelf sizes etc?

Thank you!

 

[janecj333]

When we moved into our house (built in 1910), we were lucky to find a coldroom in the garage. It is all above ground, and rarely gets above 60 F.

It has a concrete floor, walls (all solid wood) between 3-4" thick filled with sawdust, a screened hole in the ceiling, and a heavy 3" thick solid wood door that seals perfectly after 96 years. I suspect that the ceiling is equally thick/insulated.

And for all the posters who are going to comment on how crude and ineffective and foolish it would be to build a coldroom (did I mention unprofessional, inexpert, a waste of time, and 'redundant'?) to store root vegetables...don't bother. 'Experts' like you no one needs.

 

[hitssquad]

Engineering a shallow-buried passive cold-room

One problem would be that the shallow temperature cycle that you observe is a result of the dirt outside the walls. This dirt, unfortunately, cycles temperature in harmony with the seasons. Dirt does this everywhere in the United States down to a depth of about 30 feet. I believe that insulation on/in the walls would merely make it hotter in the basement, rather than colder.

One way to remedy this would be to insulate the dirt from the atmosphere and sunlight above it. If you surround the house with a horizontal layer of styrofoam or polyurethane (buried, otherwise your house will look bizarre and the foam will degrade in the sun), the dirt will be insulated from the atmosphere that is causing it to cycle temperature with the seasons. It will thus act like deeper dirt.

Extend these shallowly-buried wings far from the house to maximize the effect.

The wings will need to be sloped downward to some extent as they extend from the house, by the way. Otherwise, the wings, being waterproof, will create a drainage nightmare that will almost certainly destroy the house and turn the dirt area around the house into a permanent bog.

Conductive heat does not rise, by the way -- it propagates equally in all directions. Only convective heat rises. (It is critical for success on this engineering project to understand this. Many engineering failures might have been prevented if more people correctly understood this property of heat propagation.) Since conductive heat propagates equally in all directions, your insulation wings will not prevent built-up heat from escaping your refrigeration dirt.

If you are in Alberta, Canada, with sufficient horizontal insulation of the dirt from the atmosphere, your basement is going to get a lot colder than 60 degrees in the summer. You will have serious condensation problems on the walls, though. A dehumidifier would help in this area, and besides that it would be good for longevity of your preps -- unless they are all hermetically sealed. I would try to keep the humidity as close as possible to zero. This might be hard to do if there is not a very-good vapor barrier around the basement, and especially between the basement and the house -- the latter which will otherwise continuously supply the basement with fresh vapor, making the basement musty and moldy (which I would imagine it, like most basements, already is).

A HEPA filtration device might help somewhat with the mold problem since HEPA filters are capable of filtering mold spores.

If you implement these dirt-insulation wings, Your house is going to be colder than it is now if you don't also insulate the house from the basement. Polyurethane or styrofoam work well. Fiberglass might work -- although in almost any other insulation paradigm it is next to useless -- since heat convects upward in fiberglass and the basement is below the heat source, rather than next-to or above it.

 

[summerthyme]

You can do it hitsquad's way... or you can simply choose the northwest or northeast corner, build a partition and insulate the walls between the cold room and the basement, AND the ceiling, and go for it.

We have one built just that way.. not as well insulated as I'd have liked, but it stays at refrigerator temps between October and April, and never gets above 60° no matter how hot it gets outside.

Oh, and we have a window on the north wall... which we use for manual passive ventilation. If I ever get my wish list done, we'll install a small active thermostatically controlled vent system with PVC pipe and some small "muffin" fans.. which should keep the temps where we like them for even longer than now.

As far as shelves.. sturdy, obviously. Some folks build in bins for things like potatoes, apples and root crops.. I prefer to use crates which can be removed, cleaned and disinfected and left in the sun to kill off any microorganisms during the "off" season. I build a bunch of crates from pallets I tore apart and reused.. painted them with a couple of coats of white latex paint, and 10 years later, they still scrub up easily and are holding up perfectly.

We bought three "Gorilla Shelf" units and installed them... but used heavy, 3/4" outside grade plywood (marine grade, I believe it's called) for the shelves. Sealed it with some polyurethane... which may have been overkill, but it makes it easy to clean them if needed.

We have a stone floor in that corner (when we rebuilt our house after a housefire, I planned on putting the root cellar in, so didn't have that corner cemented) and it holds just about perfect humidity. I don't generally keep canned goods (wet canned goods.. I have one shelf unit full of dehydrated canned stuff in #10 cans) in there.. but except for the one time I made a MAJOR mistake, even regular canned goods seem to last for years without any real rust problems.

The major mistake was putting a flat of purchased tomato puree on the shelf STILL IN IT'S CARDBOARD FLAT. That pressed against the cement block wall, and wicked moisture from the wall. In 3 years, it rusted out the can bottoms until they began leaking everywhere. What a mess!!

The moral of that story is to keep everything away from the walls by at least an inch or so.

Of course, if you want it to store things like carrots and other root crops (and apples, which also like a lot of humidity) perfectly, then it will be a bit too damp to store canned stuff well. You will see rust on cans sooner or later. You can either choose to build shelves for those foods someplace else in the basement (as long as they are staying below 70° their shelf life is going to be pretty darn good) or dip each can in wax or something to help rustproof it. I store most storebought canned goods on lines of shelves which we built on the cement wall in the regular (unheated, but not opened to the outdoors to cool it down like the root cellar is) basement. I store all my home canned goods in closed cupboards (rescued from the kitchen when the house burned). Stuff lasts forever down there.. it just requires learning about the various "microclimates" (yeah, even in a basement) to figure out what stores best where. My onions and garlic proved to absolutely love the space right at the bottom of the stairs from the kitchen.. not quite in the basement proper, just a bit warmer than the rest of the cellar. It took a few years to find that out, though.

Summerthyme

 

[Deemy]

I made one (rather dh did) in our new house. We took two walls and primed the walls so no water could seep in(.along the outside walls).sorry forgot the name of the stuff. We used the third wall along the steps so that we could close up an extra storage area. We then put in insulation and and panneling. Fourth wall had a door. Note that we also used the side of the basement that was more covered with dirt outside to help keep the room warm. I am very pleased with our efforts.

 

[janecj333]

Summerthyme

 

[take 1]

Thanks for all the responses so far everyone, please keep them coming.

I never thought to mention that here where I live, when I said I have an unfinished basement... what that really means is this:

I already have:

- Concrete walls and floor water sealed from the outside and weaping tile along the base of the foundation to remove any possibility of water (all govt. certified)

- Inside walls are already studded and insulated and vapor barrier sealed.

Although this isn't a pic of my basement, it would look something like this: Photo

I don't have:

I haven't sheet rocked or installed much electrical to this point.

Sorry if my idea of unfinished was a little vauge.

 

[Deemy]

You're half way there

 

[PilotFighter]

Here in the deep south, I have seen a number of old cold rooms. The ones here stayed around 60 degrees all summer long. What they were, was a big pantry in the middle of the house. All these house were up on blocks and under the houses stayed very cool. The rooms all had a hole cut in the middle of the floor, and had a big grate with screen over it. This then allowed the cooler air under the house into the pantry. In the winter time a heavy rug was placed over the grate. My grandmother had one of these also. Still the coldest room in her old house.

 

[suzy]

Ok, in looking at the picture, it looks similar to part of our basement, the side thats finished.

Our cold room (we have two) in the basement is in the SW corner, with no insulation against the outside wall. There are shelves running floor to ceiling. The 4 foot by 4 foot little room is very well insulated from the rest of the basement, including the ceiling. No insulatin on the floor. The basement is two feet above ground level, and is insulated on the OUTSIDE wall for that two feet.

We have a steal door that closes the room (large closet) or corner off. From about October through may, it stays pretty cool in that corner, and generally stays below 50 degrees. Refrig thermometer says that it should stay below 40 though to keep food from growing the bad stuff.

Our other root celler or cold room is many years old, and under the corner of the garage. It is about 8 feet underground, with one end of the garage over it. Always cool down there, even when its HOT anywhere else. It was built with a rather primative block and some kind of mortar. Its really neat though. When we built on the lot, we chose to incorporate it, rather than fill it in. It does have a lot of moisture, a few spiders.......

suzy

 

[yellowsprings]

My storage room in the basement is a nook located under the mudroom that is enclosed with three outside walls. DH and I built a wall with a door to enclose it. There are no vents in this part of the basement but I did cut some holes in the bottom of the wall to allow ventilation to this room. I can close these off if needed.

As for shelves, I started out with some metal shelving I purchased at Lowe's. I soon found out that I can store very little weight on these (despite what the box says). My new shelves are going to be the extra sturdy shelves at Sam's Club. They are on wheels and I will be able to move them as needed.