The Twinside Retaining System is a cantilever retaining wall. Fundamental to the system is the principle that the posts MUST BE CEMENTED into the ground the same distance as they protrude above the ground.
The Twinside Product: Twinside retaining panels are reinforced, measuring 1430mm long x 300mm high and 60 mm thick. Each panel weighs approximately 50kg and reinforced posts weigh approximately 10kg per 300mm.
Installing a Twinside Retaining Wall
Dig a hole at one end of the wall with the dimensions of 300mm x 300mm x the height of the wall. To ensure the hole is the correct depth, set the post down and measure the amount protruding above the ground. The posts should lean 2º into the load, i.e. towards the high side, the ground that is to be retained. Concrete the first post in using a ratio of 4 sand, 2 stone and 1 cement, or use the sand removed at a ratio of 8 to 1 cement by volume. Fill the hold around the post to ground level.
Use a string line to mark off every 1500mm centres. When digging the holes use a rod the same length as your posts to ascertain the correct depth of the holes. Raise the string line to the height of the wall to ensure that the posts are of the right height.
To make sure the distances between the posts are correct before cementing in further posts or putting a panel in, it is recommended that a piece of wood or a rod be cut to the same length as the panel plus 10mm, i.e. 1440mm. You can then test to see that the panels will raise and lower in the grooves with no problems.
It is also recommended that you place one panel in at a time. This gives the concrete some time to cure and also holds the posts steady whilst you dig more holes.
When carrying a panel, please remember to hold it vertically as it places less strain on the centre of the panel.
Place the panel in with an offsider and ensure that it remains horizontal in the grooves and does not jam. It is also important that the panel is the right way up, that being with the narrower edge on top.
Do NOT backfill straight away. Leave for a few days so that the cement footings can cure.
If compaction is required, do not use machinery to compact. Spraying water from a garden hose is sufficient for compaction.