Tires as footer/foundation for straw bale house

Hi Chris, welcome.

I am planning a straw bale house and wanted to bypass the cost of pouring a cement footer for the straw bale walls to go on. Also my build site is on a slight grade so several courses of tires would bring the base of the bales above the dirt line.

I would run two courses of 4x4s with nails nailed half way in every 6 inches on the inside which would then be filled with cement (or possibly a cob mixture), ensuring a solid connection and fastener for the bale walls.

The bale walls will be in-fill not load bearing.

Can you see and problems developing?
Would filling the bottom plate on top of the tires with cob instead of cement be strong enough?

Thanks, Phil Nafziger

Hi, Phillip and welcome to these forums...I see your question has gone unanswered so thought if I bumped it up and added it to the 'straw bale' forum someone would give you some input.

(thanks Judith...this got by me...sorry)

Hi and welcome to Permies Philip,

I am planning a straw bale house and wanted to bypass the cost of pouring a cement footer for the straw bale walls to go on. Also my build site is on a slight grade so several courses of tires would bring the base of the bales above the dirt line.

Photos and a design would lend validation yet your logic is sound dirt line is what is known as grade. As long as you plan well water mitigation through proper drainage, and tectonically stabilize the tire armature tieing it all together you should be fine. I always recommend a PE approve the design unless you have the skill sets to do this work yourself, and/or the knowledge-experience to back it up.

I would run two courses of 4x4s with nails nailed half way in every 6 inches on the inside which would then be filled with cement (or possibly a cob mixture), ensuring a solid connection and fastener for the bale walls.

I am only visualizing part of this...I think...there are better systems and I would avoid the OPC (cement) completley.

The bale walls will be in-fill not load bearing.

Excellent

Can you see and problems developing?
Would filling the bottom plate on top of the tires with cob instead of cement be strong enough?

Really need more detail and photo of similar examples and/or diagrams to give more succinct advice.

Regards,

j

Thanks for the input J.

"Really need more detail and photo of similar examples and/or diagrams to give more succinct advice."

Do you have any ideas on how to attach a bale wall to a tire pony wall?

Do you have any ideas on how to attach a bale wall to a tire pony wall?

Hi Philip, et al,

Well you may not like my first answer. I don't care for, nor would I facilitate SB load bearing systems in most cases. I would use a timber frame with sill beams and infill with SB or "slip straw clay" panels. If one was to choose forgoing a timber frame structural armiture, and just us SB I would recommend a full "tensioning system" of either GAC 3/8" cable and/or synthetic fiber rope/webbing that brings the tire pony wall and the rafter plate in oblique and direct tensioning loads through the SB wall matrix. A rope/cable tensioning system would be the only way I would ever consider a "structural" SB assembly.

Regards,

j

My plan is post and beam, sorry about the miscommunication. Typically with post and beam most people start with a slab in which case a bottom plate is fastened to the concrete and the SBs in turn are fastened to the bottom plate. In my situation I am not pouring a slab instead I will be fastening the SBs to a tire "slab".

Hi Philip,

That couldn't make me happier!!!

I don't like OPC and avoid the stuff wherever I can on a project. So now you just have to come up with which of the methods to tie this foundational pony wall of tires and sill beam (plate) all together. This can be done with bolts that fasten each course of tire together before they are filled working in concert with a GAC cable and/or synthetic webbing that tension the entire mass together.

Frankly, a simple "toggle rock" between each course of tire can do a great deal of work in stabilizing a wall, and the list of "strengthenings" just go on from there. Take a look at some of the building methods of the Hindu Kush like Koti Banal architecture made of timber and stone, and you will get even more germane ideas.

I can not go into to much more detail without developing CAD drawings and blueprints. So I hope you are doing that, and/or have a design-builder with this kind of experience. I can critique or vet such plans when you have them. All I ask is that you post them here publicly for feedback and so others may learn. I provide that consulting, where and when I am able, to Permies members that are willing to make the more detail effort of actually "journally a project" on Permies.com. Without the details it's really hard to be more specific. Please keep asking your questions...it sounds like a great plan thus fare.

Regards,

j

Thanks for your time! I will be drawing up the plans myself and when they are done I will share for additional critiquing.

Phil

Hi, I'm based in the UK and just came across this site and topic which I've also been researching. It might be a bit late, there's a UK company that's come up with a design for using tires filled with gravel as straw bale foundations which might be of interest. The design appears to have UK building regs approval, which is a big deal here! Drawings here:http://www.strawworks.co.uk/wp-content/uploads/2013/02/SD-Car-tyre-pillars-130226-05-29.pdf

Best wishes,

Mark

Mark,
Thanks for the post and link! Very helpful and encouraging!

Do you have any experience in this area? I haven't heard of anyone packing tires with gravel until now but in sure it can't be any more difficult than packing them with soil.

Hi Phil,

I've never tried this method personally, as I'm only beginning my research on the best self-build methods for me, but if you look at the 'Technical Details' of strawworks.co.uk (http://www.strawworks.co.uk/technical/) it gives you a history of its development and use in the UK. The completed Projects gallery shows a couple of actual examples including a classroom built in 2002: http://www.strawworks.co.uk/projectsgallery/. Finally, there's another drawing showing the tires in-situ here: http://www.strawworks.co.uk/wp-content/uploads/2013/12/Strawbale-self-build-housing-with-drawings.pdf.

I plan to go on one of strawworks introductory courses in September in London, so will be asking them about this method in some detail, specifically how to get the levels all equal.

Mark

r

Hi Phillip,

Congratulations on deciding on post and beam straw bale construction. I have been in my bale for about a year and a half now and it is truly a wonderful experience being in a natural home that is so well insulated and comfortable. I built my home myself, but I had my it professionally designed and then certified by a third party structural engineer before going to my local planning office. This service cost me about $2K US, but I found the piece of mind as well as ease of permitting well worth the money. I do not have any experience with tires as a foundation, I opted for a basement on my home, but I would proceed somewhat cautiously. For one, straw bale homes are very heavy - much heavier than a conventional home and if you are going the timber frame route, you will be astonished by the amount of lumber needed to handle the loads and prevent racking due to wind. My concern would be the tires shifting under the weight of the home or the sheer of the wind. I cannot imagine anything worse than a moving foundation - this could jeopardize the entire home. Moisture and integrity of the tire walls themselves would also be concerns for me. Most used tires are past there prime and one cannot be certain how old they are or how they have been stored. Too much degradation and extreme weight could be a recipe for disaster. If I had not opted for a basement. a rubble trench foundation would have been my foundation choice. Good luck.

After a little time has passed, I now conclude that using tires as a foundational element for building is unsuitable for my situation. If slave labor were available I would reconsider, but until then I will figure out other measures for creating affordable and efficient ways of building a foundation.