Tips on building an earthship retaining wall from old tyres

The backyard after the excavator had terraced it.
The backyard after the excavator had terraced it.

As we live on a steep slope we've had to build a lot of retaining walls in order to create functionalilty around access, water management and food production.

We've used a range of techniques to do this including working with old car tyres to build a big earthship retaining wall near our house.

Earthship construction is a technique of building developed by Amercian architect, Mike Reynolds. He's famous for using 'rubbish' and earth as building materials.

We chose to build an earthship wall as we had a small budget and a lot of excess subsoil left over from initial earth works.

We also knew we could get car tyres for free from the local car yard.

We hadn't built one of these before, so spent some time on YouTube to learn how.

While it's pretty easy, it's also a lot of hard work. It would have been easier if we had heaps of people to help, one of these cool whakker packer tools and *dry* gravely soil instead of wet, sticky/clay subsoil.

This last tip is a really big one, the guy on the YouTube video made it look like a walk in the park with his dry, sandy soil.

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He just poured it into the tyre and patted it down, in contrast we shoveled, packed, whacked, shoveled more, had a break and then came back and whacked more. It was a bit of a mission.

But it's a bloody strong wall and used up a lot of our excess subsoil.

Starting out, we cleared the space, tacked on some white geo-fabric to the bank to keep it from dropping crumbs and made a level pad to start laying tyres.

As we were almost on bedrock, we didn't have to lay any sand/concrete for foundations, we just levelled it off.

As soon as you start building up from your first tyre, you have to find a way to plug the holes so the earth doesn't just fall through.

We had a whole pile of carpet tiles the previous owner had left under our house which fitted perfectly, so we used them.

We also back-filled the area behind the tyres with 20mm blue metal and ag pipe to guide excess water out of this area to a safe spot.

Pound, pound, pounding. There was a lot of this and Anton did most of it - he is forever the best.

We went five tyres high and angled them all slightly back for structural integrity.

An important thing to note is that if you go over one metre high you need an engineer (in our region) to design/approve things.

Because of this we didn't exceed this limit - it might look taller, but that's because the earth around the wall had been excavated and the paving hadn't been put down.

The next step involved plugging the holes with subsoil, the best approach was to form balls of sticky soil and throw it really hard into the gaps and then pat it in to make sure it's all bedded down.

After that, we wrapped the whole wall in chicken wire, this is what the external renders 'hang on' to and helps create a smooth, level surface.

We chose concrete render instead of earth for two reasons, the first being this wall is in the coldest, dampest area of the whole property so it needs to be able to handle long months of never seeing the sun and being constantly wet.

The second reason is that we're not overly experienced with earth building, so took the conservative approach.

Anton did the paving around this area using recycled bricks. This was the final job before we painted the wall to look all fancy.

In addition to all the 20mm blue metal and ag pipe that's behind the wall, there are also drainage holes at the base of the wall.

These are necessary as you never want water building up behind a retaining wall.

  • Hannah Moloney and Anton Vikstrom are the founders of Good Life Permaculture, a landscape design and education enterprise regenerating land and lifestyles.
This story How to build an earthship retaining wall first appeared on The Examiner.