Tires in cob house foundation?

my question is, can i use tires for the foundation on a cob house and if i can, how would i cover them when it comes time.

Welcome to Permies, John!

Give us a little more detail about what you have in mind. Are these tires going to be staked into the ground in some fashion? Are they laying down or standing up? What kind of soil do you have? If you are in MO, are you in one of those places where you need a pushbroom to dig down to the bedrock?

As far as covering them over, there's lots of ways you can put some lathing wire over them so that you can slap some cob over the whole thing.

first, my land is all heavy clay with about 6" max topsoil, what i had in mind was doing the rubble foundation and instead of using rock pack the tires, (another question there, what to pack them with to keep moisture out of cob) and stack them a min of two high and yes, i planned to use re-bar to anchor the tires with enough sticking out for the cob to have something to latch onto. thank you

Suggestion: Bend your rebar into a U shape and don't drive it into the ground (you don't want water coming up through it and rusting it). Put a couple-three inches of rubble in the bottom of your trench and set your rebar Us with the open end up. If you need to stabilize them for the next step, you may need a board with two holes to lay over the top of the trench. Next step is to pour some concrete into the trench (at least 4"), which will set around the rebar and make a good footer for the rest of the foundation. Once the concrete sets up, you can continue adding rubble and then set your tires.

The concrete with the rubble under it will act to keep soil moisture coming up into the cob wall. If it's really wet where you are, you might even want to form the footer so that the top of it is a couple of inches above grade.

P.S. Odd what you have to do here to say "bend something into a u-shape".

yes i noticed the (shape "you") thing, it is strange. i understand with the rusting factor, thanks. the bending the re-bar into a (shape "you") also makes sense. the only issue i have is using the concrete. is there ANYTHING else i can use in its place, if i have to i will but i prefer not to. and any suggestions for what to pack the tires with? could i use cob perhaps? do you think mixing something like clay, aggregate and linseed oil with nothing organic could take the place of the cement? trying to avoid cement. once again thank you.

I can appreciate your desire to avoid cement, but as I said on another post, don't think that reducing your carbon footprint means that you aren't allowed any footprint. Cement was made sustainably using wood fires since Roman times. It's only now that fossil fuels are so readily available that it is a "bad" material.

Cement is a great improvement over burnt lime (which itself requires burning some fuel), and if there is one place you should give a little on your principles, it is with the construction of the footer. A footer doesn't take use that much concrete, but it can markedly improve the stability of the building.

Of course, if there is a granite quarry around and you can get some blocks of granite for a foundation (like I have seen at old ghost towns in Nevada), that would make for a cement-free alternative.

oh, it's not because of the footprint it is to use as much from my land as possible. i do plan to use cement for the footing. my reasoning is also to do with supporting big corps. there is only a limestone quarry around. i am just mainly doing my best to use only materials i have on site and i can get locally. for example, sand and straw comes from local farmers and the clay and timber from my land. i performed multiple soil tests and literally have only clay under the top soil. thank you

Cement is a great improvement over burnt lime ...

I (as well as a number of traditional "lime masters" from the UK, France and a few other places) could debate that one John...


One of the key differences I point out to folks new to the building arts is some peculiar characteristics of certain construction materials. Some of the foundational elements are the strangest of these, which are often wrapped in hype and misinformation by the industries and normative cultures behind them. First, let me say I am not completely against concrete, though I do prefer the natural cements over most "industrialized portland's" professionally referred to as OP (ordinary portland) cements. One of my main concerns with OP cements is there possible (probable) degradation over time. Think about our failing bridges and highways that are less than 60 years old, compared to the Roman roads of hand set gravel and stone that are still functional today over 2000 year later. Another challenge with OP cements is its inability to breath, stay wet, and promote "moisture issues." The easiest metaphor to use (or comparison) is to think of OP cement as a cotton sweater, and think of lime and clay (cob, adobe, bousillage, bajareque, daubing ) as a fleece or wool sweater, if they get wet, which one do you want to wear, or live in.

Not that I am recommending it, but you can also use "soil cements" with natural cement or lime binders and certain chemical or enzymic additives. Some of these will yield higher psi that OP cement alone, but it will add cost and more technology to the project.

Back to your original question, "do you have to use cement?" Absolutely not, and I would go further to say that the majority of the domestic architecture in the world today and in antiquity is (was) not sitting on any cement at all, but exactly what Frank Lloyd Wright and many other brilliant builders through the ages used...gravel and/or hand packed stone in a trench or pad. The oldest and some of the most tectonically stable buildings in the world sit on stone plinths/footers, with gravel underneath...not OP concretes. Just look at what happened in Haiti in 2010, if you think OP cement is a good way to build, or the "earth structures" in Yemen that once inspected they started finding evidence that many either hand not been properly maintained and/or repaired/modified with OP cement, while others that had been much older, but not modified stood strong.

thank you for your reply jay c, i have access to all the clay i can stand and i have a cheap supply of limestone and river sand, what is the chemical or enzyme that i would have to add? i am a painter by trade, however i know pluming, electrical, and rough framing, i have no real experience to speak of with different types of cement materials, any help you could offer would be great. thank you

Hi John,

Dig into some of my info and contacts, develop questions, and I will do the best I can to answer. I have helped with creating some "soil stabilized" projects, but personally like plain old "traditional" methods of construction above any "rethinking" or "reinventing of wheels," but again, I will help where I can. If you read through the attached infor, you will learn much and probably develop some additional ideas, and questions.


https://www.google.com/search?q=soil+cement+stabilization&oq=soil+cement+stabli&aqs=chrome.1.69i57j0l5.16580j0j7&sourceid=chrome&espv=210&es_sm=122&ie=UTF-8#es_sm=122&espv=210&q=lime+stabilization+soil+foundation&safe=off

http://www.limeworks.us/

http://www.americanlimetechnology.com/tradical-hemcrete/

http://www.geopolymer.org/category/archaeology/roman-cement

http://www.naturalpozzolan.com/index.html

http://www.naturalcement.org/

http://www.romanconcrete.com/index.htm

http://www.rosendalecement.net/index.html

http://www.kalmatron.com/

Jay C. White Cloud wrote: The easiest metaphor to use (or comparison) is to think of OP cement as a cotton sweater,

Don't you mean polyester, Jay? Cotton is still a natural material, whereas polyester is a product of our modern industrial age, just like OP cements.

I suppose I should edit my previous statement to say that "given proper attention to detail, cement is a great improvement over burnt lime". At one government facility where I worked, it was obvious that little attention to detail had been given when pouring the steps in front of the building -- the concrete was spalling everywhere.

John Elliott wrote:Odd what you have to do here to say "bend something into a u-shape".

Yeah, it's to stop 'text-speak'-there's a bunch you can't use...
It's a bit hard on these forums, where there seem to be a lot of 'u-shaped' things!
As you've noted John, it's fine if it's not on its own.

thank you jay i am reading up on the roman cement, and leila thanks for letting me know how to use the -u-

Hi John E., et al.,

If you are "pulling my leg" about the cotton vs. Polyester...read no further as it did make me laugh

As for the actual comparison I meant cotton, because even polyester pulls moisture away and dissipates (desorbs) it efficiently for evaporation, the opposite of cotton. Cotton, and concretes in general are very similar in they both act like a sponge, absorbing in water and holding it.

You can think of concrete as highly hydrophilic, and cob and lime as both hydrophobic and hydrophilic.

Wool fibre has a hydrophobic (water repelling) exterior, and hydrophilic (water loving) interior that confer its unique moisture management properties – properties that are not shared by synthetic fibres such as nylon or polyesters which simply wick the moisture away and allow fast evaporation. Clay and lime share very similar characteristics similar to both wool and polyester fleece, unlike concrete which take on (absorbs) moisture and does not release it (disorb), like wool and polyester fleece.

In contrast to most synthetic fibres, wool has the capacity to remove large amounts (up to 35% of its own weight) of moisture from inside a room, before the fibre
even begins to feel wet. Lime and cob behave in a similar fashion vs concrete which not only feels wet but is wet when humidity is above 70%.

Unsealed cob and lime's chemical structure means that it has the ability to actively absorb and desorb moisture and to gain and release heat depending on the external and internal environment – thus buffering a room against environmental changes.

Cob and lime's ability to absorb moisture may result in a reduced propensity for condensation within a room.