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General: Rammed car tyre foundations

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    • CommentAuthorNome
    • CommentTimeSep 1st 2009
     
    Let's start at the bottom...

    Is anyone here experienced with rammed tyre foundations? I love the idea - it sounds like a lot of hard work but is essentially free and the tyres double as a waterproof barrier too. But I need some clarification...

    The tyres form a stem wall, sitting on the top of the ground, right? Presumably they also need their own foundation beneath, to stop them sinking - a rubble trench perhaps?

    This is probably a proper noob question, but... what actually attaches the foundations to the ground? From the diagrams I've seen so far, I'd be kinda scared of my building blowing away.

    By plastering the outside of the tyres with the same stuff used for the walls above (strawbale walls in this case), doesn't any moisture wick up through the plaster to the bales? (This question applies for many types of foundations I suppose.)

    Is there any mileage to making the whole floor out of rammed tyres? Seems to me they'd provide additional thermal mass (I'd hate to use concrete) and do the waterproofing thing too. Obviously gaps would have to be filled in and the whole lot would be topped with... more rammed earth? Soil-cement? Clay tiles?

    (And are solid floors even permitted in the UK? I'd much rather have the earth under my feet than a big expensive timber frame.)
    • CommentAuthorCWatters
    • CommentTimeSep 1st 2009
     
    You can have a soild floor in your house. Might need some insulation in it to get the overall house to comply with Part L.

    Have to say I'm not entirely convinced by the need for tyres in the floor. Don't they leech chemicals of something?
    • CommentAuthorJulian
    • CommentTimeSep 2nd 2009
     
    Hi Nome
    I have seen tyres used in this way: trench 800mm filled with <10mm aggregate (in this case crushed recycled concrete), tyres in two courses (layers) on top and these filled with same aggregate. Sole plate on this. This for a straw bale building. All Architect's design and agreed by building inspector and structural engineer.
    • CommentAuthorNome
    • CommentTimeSep 2nd 2009 edited
     
    The 'need' is for thermal mass and drainage/waterproofing using free recycled materials...

    I've read differing things about chemical leach - of course there will always be people that scream DANGER! But arguments include:
    - old tyres have already done most of their off-gassing
    - biggest chemical leach would be zinc, which is present in the soil anyway and vital for plants (although there is some nastier stuff in there too)
    - treated lumber contains much of the same nasty stuff
    - if tyres are well-made, chemicals are deeply bonded into the material and shouldn't go anywhere
    - tyres are most likely to leach chemicals if very wet, so if protected from the elements and allowed to drain, the danger is far less
    - whatever they leach, it's still better than burning them

    (And people have been growing potatoes in them for ages!)

    Hmmm, if you stuffed the tyres with an insulating material like LECA I guess it would help, but LECA is not free and absorbs moisture - doh! Not sure what might be suitable... I suspect tyres have insulating properties themselves - they're certainly used for noise insulation - don't know if there are any figures out there for them though!
    • CommentAuthorNome
    • CommentTimeSep 2nd 2009
     
    Good stuff Julian, thanks. Do you know how the whole lot was fixed together?
    • CommentAuthorbiffvernon
    • CommentTimeSep 2nd 2009 edited
     
    We've just been doing a non-structural straw build. Tyres on the earth, filled with earth and a godd bit of jumping up and down thereupon. Then a 1200guage plythene sheet and then the starw bales. Bales are pinned through with hazel rods, the ones in the lower two layers going straight through the tyres, and the poly sheet, into the ground below. Buildings don't blow away because of gravity rather than being fixed to the planet. Moisture control is not so much as stopping all capilliary action but allowing enough 'breathing' to ensure that the rate of evaporation potentially exceeds the rate of moisture ingress.
    Pictures at http://www.faeriehouse.tithefarm.biz
    • CommentAuthormenzies
    • CommentTimeSep 2nd 2009
     
    Biff, just had a look at your website. I want to come work for you...!
    • CommentAuthorNome
    • CommentTimeSep 2nd 2009
     
    So do I - that looks awesome!

    I had wondered about hazel rods but I thought the middles of the tyres had to be filled with gravel to allow drainage. Thank you.
    • CommentAuthordjh
    • CommentTimeSep 2nd 2009
     
    nome, amazonails have been involved with several straw bale buildings with car tyre foundations, and also with various kinds of solid floors. Well worth talking to them. Also, I believe perlite is an alternative to leca. Still costs money, of course.

    biff, are your bales sitting directly on the poly? I thought it was normal to stand them off so water could drain below the bales; usually by using a timber ladder sole plate filled with gravel or leca etc. Won't bales on poly get wet feet? I'd also be interested to hear how the roof works out with poly directly above the bales. Perhaps expecting condensation there is just a myth in faerie land!
    •  
      CommentAuthorjoe90
    • CommentTimeSep 2nd 2009
     
    I am considering rammed earth tyres for under a strawbale build but am tending to think compressed stone (graded stuff they use under roads) may be better. Having read the threads on "interseasonal store" I am convinced it is better to NOT put insulation below floor slab but put insulation vertically in the foundations. This would give lots of mass below the floor to store heat and reduce temp fluctuations. The house is being designed to face south and have lots of solar gaining windows. I am considering using 200mm of insulation vertically in the middle ot the foundation trench and backfilled both sides with the graded stone as above. The insulation would extend up to the middle of the straw bales with a ring beam of concrete either side to suport the bale wall. Obviously a DPM needs to be included. Thoughts!!!
  11.  
    A couple of good points, djh. Firstly, Amazonnails tend to do their work very well. All rather gold standard stuff, complying with building control and using straw bales structurally. Ours is just a non-structural hovel.

    Yes the bales do sit directly on the poly. If water got onto it somehow and didn't leak out through the puncture holes made by hazel rods then there could be puddles forming. But I suspect water won't get in, at least not at a rate that it can't get out again pretty quick.

    I too will be interested to see how the roof performs. I followed Tony Wrench's suggestions. He's lived in his for ten years. Again, I'm hoping that any condensation under to poly in the roof will drain/wick away and evaporate too quickly to develop a moisture content in the straw that will support mould growth. I'll let you know in a few years.
    • CommentAuthorJulian
    • CommentTimeSep 2nd 2009 edited
     
    Hi Nome
    As Biff says (of his experience) tyres in the building I worked on were simply stacked and filled and not fixed either down or together. The assumption (from architect and BC) was that moisture would not travel up through the crushed concrete gravel.
    • CommentAuthorNome
    • CommentTimeSep 3rd 2009
     
    Cool, so it really is as simple as it sounds. I will definitely talk with amazonails - it seems like a must with a strawbale project!

    Would be interested to hear what people think of the tyres in the floor. More effort than it's worth? Anyone know what BC will require from a solid floor?
    • CommentAuthordjh
    • CommentTimeSep 3rd 2009
     
    Biff, thanks for that. I'd not thought about the holes made by the hazel rods; they should improve the odds somewhat. I look forward to hearing about the roof!

    Nome, I'm not sure what the car tyres in the floor do? A layer of gravel can be used as a capillary break but it doesn't need tyres to support it everywhere. It just needs support around the edge.

    Cheers, Dave
  15.  
    Happen I was talking to a structural engineer last night who deals with things like dew points in roofs. She looked at ours and thought it would probably be Ok because the dew point was likely to be well short of the impermeable membrane. There will be a temperature gradient across the 45cm thick layer of straw that forms the roof below the plastic. The position of the plastic will be well in the cold, sub-dew-point zone.
    • CommentAuthorNome
    • CommentTimeSep 4th 2009 edited
     
    You don't think it will add significant thermal mass?

    If not then I will happily drop the idea - I can do without the extra work!

    I suppose simply tamping the earth beneath would have a similar effect.
  17.  
    I'm going for a thick layer of mud on the inside of the straw bales for thermal mass.
    • CommentAuthorJulio
    • CommentTimeJun 13th 2011
     
    Restarting an old thread I am afraid. I am wanting to put masonry on top of some tyre foundations, does anyone have experience of this? Does a good thick mortar bed do the job? Hope to hear back from someone..
    • CommentAuthorRachel
    • CommentTimeJun 15th 2011
     
    we have used tyre foundations well for straw bale builds...
    one note; on tests carried out for a council on the strength of rammed tyres; they deemed to be stronger than concrete...
  20.  
    Rigidity is the thing is building traditional masonry, it also depends on what your rammed tyres are sat on...

    J
    •  
      CommentAuthorjoe90
    • CommentTimeJun 15th 2011
     
    James Norton,

    I guess that is also true of concrete?
    • CommentAuthorMikeRumney
    • CommentTimeJun 20th 2011
     
    Posted By: CWattersYou can have a soild floor in your house. Might need some insulation in it to get the overall house to comply with Part L.

    Have to say I'm not entirely convinced by the need for tyres in the floor. Don't they leech chemicals of something?


    This came up recently in a thread in "Offers and wants" ... As far as I'm aware tyres will leach all sorts of nasties, but only if the metal is exposed because they're "bald" or have beem chipped.
    If you do decide it's worth the extra effort and you are looking for tyres there are about 50 on offer in Glucestershire!
  23.  
    Posted By: joe90James Norton,

    I guess that is also true of concrete?


    Your reinforced ring beam does this job nicely.

    J
  24.  
    Tyre foundations back again!

    I'm thinking of using them as a strip foundation for a straw bale infill build and also a post and beam sunspace. My question is what do you think is the best way to connect the vertical wooden posts to the tyres?

    The tyres will either be rammed earth or filled with aggregate. I've rammed tyres in New Zealand, amazing how much earth goes into each one. I don't know if I can be bothered, especially as we had a hydraulic press over there to help speed up the compaction....
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 27th 2012
     
    Did we ever get to the bottom of whether it is legal to bury them here?
  26.  
    Hello hello

    I'm looking for a little help as I have been presented with a bit of
    problem on a strawbale project we're about to (hopefully) start.

    My engineer, who is normally very good (and helped me to do
    solid masonry foundations with no OPC on another bale project 2
    years ago) has spat the dummy over a car tyre foundation on an
    upcoming project which has passed planning and is waiting to go. His
    main concern is the longevity of the tyre, and the fact that there is
    nothing bonding them together - both of which sound like pretty flimsy
    arguments to hide the fact that he doesn't want to step outside the
    box on this one. I tried to explain that they're in common use, but
    it's not going to fly I'm afraid.

    If there is any data available I could try and convince him with that
    would be great, as it would be nice to spread the knowledge so to speak.
    I suspect however he's not likely to come on board anyway - engineers
    have to think they are right I guess!

    So, could anyone recommend a friendly engineer, or have you
    successfully passed building regs without an engineering cert?

    I know technically if you can prove that what you're proposing is sound
    then in theory you don't need one for BCO, anyone tried this?

    I hope you can point me in the right direction, or possibly offer some
    professional assistance?

    Just to save the obvious suggestion, I have tried to contact Amazonnails
    on several occasions, and more recently Straw Works as it now seems to
    be called, but never had any replies, so hopefully someone on here knows
    a more willing professional or a quick fix?

    VBR

    James.
    • CommentAuthorseascape
    • CommentTimeJul 6th 2012
     
    Structural Solutions, Bristol - google it, they have worked on one rammed tyre studio I think.
  28.  
    Try StrawbuildATgmailDOTcom - Bee Rowan's part of the ex-Amazonails
    • CommentAuthorEd Davies
    • CommentTimeJul 7th 2012
     
    http://www.sureline.org.uk/ecotect/the_build/build1.html
    http://www.sureline.org.uk/

    Very helpful when I asked him about the bottom surface of his floor the other day.
  30.  
    Many thanks for the superb responses. I'm sure I should be able to find a way through with this selection to choose from. I'll make some enquiries next week.

    Always nice to know if you don't know, you know a man who will. What a fantastic resource this forum is!

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