As Spring draws closer, I am nearing the end of my tyre ramming in the back garden. I am just completing two retaining walls and a foundation trench consisting of over 300 tyres. While I’m sure this does not make me an expert on the subject, I feel that building in the area that I am, I have had to cope with challenges that are not normally faced by other blogs on the subject I have read. My construction of the first wall was admittedly amateur in places, and I want to do my bit to ensure that anyone else taking on the task of constructing a retaining tyre wall does not make the same mistakes as me.
When you are looking to build a retaining wall, you need to think about a couple of aspects, which I will address below:
- Use of the wall
- How you want the wall to appear afterwards
- Height of the wall
- The type of soil you are retaining
Use of the wall – do you want it to be waterproof?
One of the mistakes I may have made with my first tyre wall is not considering this aspect. My tyre wall was just thrown into the ground, not thinking about putting a waterproofing membrane behind it with a drainage trench. Some people raised concerns about the water behind the wall pushing it over, but I found that the water simply seeps through the small gaps between the tyres.
If you want the tyre wall to be waterproof, you should consider a french drain design with a waterproof membrane between the drain and the tyres. This means any excess water will drain down the french drain and out through a pipe you can install in the wall, or wherever you want. By doing this, you ensure that your tyre wall will be waterproof, which is ideal if you are using it for an earthship style building! For information on waterproofing, skip to the end of the post.
How you want the wall to appear afterwards? – Do you want to plaster over it?
If you want to avoid the bare tyre look on your finished wall, you will have to think about plastering it. On an exterior wall, this is going to be difficult using natural materials, but it is not impossible. One thing you have to ensure you do, however, is waterproof the wall, so that there is no water leaking through gaps! This in itself brings its own complications. I’ve tried to outline these at the end, followed by a section on plastering.
Height of the wall – How much are you retaining?
In my building work, I have built a tyre wall six courses high. This stands approximately five feet, or 1.5 metres, maybe a little higher. I don’t think I would be comfortable going much higher than this the way I am building, as my walls are pretty straight, albeit with a slight step back as it goes up. I also have iron rebar through the walls to act as reinforcement. If you are looking at building walls approaching 2 metres (around 7 feet) or higher, then you should definitely consider two things, the length of the wall, and stepping the wall back as you climb. If the wall is longer than, say 5 metres, (about 5.5 yards) then consider either curving the wall or building in a buttress to strengthen it.