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?

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!

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

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.

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!!!

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.

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

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.

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..

Rigidity is the thing is building traditional masonry, it also depends on what your rammed tyres are sat on...

J

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!

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....

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.

Try StrawbuildATgmailDOTcom - Bee Rowan's part of the ex-Amazonails

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!