12 May 2012
How to build a retaining wall from UPRIGHT or VERTICALLY placed sleepers.
The advantage of using vertically placed railway sleepers is that you can vary the height of the wall in different places, and you can create a curved wall, rather than straight. Constructing a retaining wall out of upright sleepers is pretty straightforward. Simply dig a trench, lower the sleepers in vertically side by side, and then backfill with a dry concrete mix, that you can ram down around the railway sleepers untill the wall is rigid. The advantage of a dry cement mix is that whilst constructing the wall, you can take out and re-position the sleepers without getting wet concrete everywhere. If the ground is damp, the concrete will set without having to add water. If not, simply use a watering can or hose.
Having fixed the sleepers in place and set the concrete, you can also connect the backs of the sleepers together, with lengths of wood, metal strips or wire. That will help to strengthen the retaining sleeper wall, if there is any pressure at any one point by soil pushing the sleepers forward. This system should equally work in a curved wall situation.
The depth of the trench depends on the height of the wall, and the pressure of the earth or material you are retaining. Allow for when the ground is sodden, and the pressure increases. Some landscapers go with the saying: 'one third in the ground, and two thirds out'. So, you'd probably need to be thinking of putting the sleepers in about 0.5m in the ground if the sleeper wall is 1m high.
Remember to think about drainage. If there's going to be water building up behind the wall, where will it go? Some people place a layer of pea gravel, or drainage pipe at the base of the sleeper wall, before backfilling with soil, so that the water can be channelled out.
How to build a retaining wall or raised bed using sleepers stacked horizontally.
The most important thing is that the sleepers are laid on a surface that is level and firm. Perfectionists and Engineers will do this on a foundation of concrete, but more mortal people will often simply use gravel or hardcore or sand or even the soil itself if it is solid. There are advantages of using something that will enable drainage of the raised bed or retaining wall, otherwise you are constructing a raised pond !
If you are stacking the sleepers horizontally on their broadest side, e.g. on the 250mm width of a 250mm x 125mm sleeper, then all you need to do is to overlap the joints of the sleepers, from layer to layer, like building a brick wall, and fasten each layer to the layer below with timberlok screws or similar. You have now created a structure that is interlocked, and could be picked up in one piece by a crane ! (If you had the inclination !) An exception to this, is if you build a long straight wall that is more than several sleepers high. In this case, you may need vertical retaining posts (or even sleepers), along the length of the wall, to support the wall from leaning forward. In this case, simply concrete the vertical posts into the ground, and fasten the stacked sleepers to the posts with Timberlok sleeper screws. (see website page for sizes and details).
If you are stacking the sleepers horizontally on their narrowest side, e.g. on the 125mm width (on a 250mm x 125mm sleeper), and two or more sleepers high, then you will need to support the sleeper with vertical posts, to stop them being toppled over by the weight of the soil or whatever.. Simply dig a hole and fix the vertical retaining posts (or sleepers) in with concrete. When you've done that, you can simply stack the sleepers against the post, and fasten together with Timberlok sleeper screws (See website page for sizes and deatails)
An exception to this is if you are building a raised bed or pond that is square or rectangular in shape, and made up of only one sleeper per side. In this case you can connect all the sleepers together at the 90 degree corners without any retaining posts.
VOTE OF CONFIDENCE!
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