Page 21 - Landscape SA 102

ALLIED TRADE FEATURE

Terraforce stairs and retaining blocks

Beyond a certain height, does a from a manufacturer with the actual SANS proven track record, quality assurance and
wall become unsafe? 508 mark. Some manufacturers state international standard design software.
“manufactured to SANS 508 standard”
SF: Walls up to 22m high at 87 degrees but that means they do not actually have General safety guidelines and
have been constructed in other countries. the mark and the design engineer must regulations
design for the correct block in the correct
SD: All walls are safe if the engineer has application. Remacon Products provides SF: This is according to the standard Health
designed them for height, loading and soil an in-house structural design service and Safety laws, namely the OHS Act.
conditions, and if the builder has followed for retaining walls, which according to SD: All walls higher than 1.4 metres must
that design. Similarly, the safe height of a building standards, are all walls higher be designed by a registered, competent
low block wall will depend on these same than 1.4 m. person; wear safety PPE which generally
factors, as well as the filled weight of the includes full length clothing and steel
block and the angle at which it is installed. SD: It would be wrong to say that one capped work shoes; keep the site clear
The steeper the wall and the lighter the block type is safer than another without of obstacles that can cause trips or falls;
block’s weight per m2, the higher it can considering the holistic design, but certain take precautions to prevent fall hazards
be safely installed. Most councils have features make some blocks more stable and risks; ensure that all tools and lifting
benchmarked this height to be 1.4 m but it than others, namely their weight per m2, equipment are in good working order;
really depends on these variables. the interlocking properties of the block ensure that the embankment supporting
and its resistance to crushing. the wall slopes backwards at an angle that
Which types of blocks are safest? is safe from collapse; ensure that the top
HR: This depends on the block design, of the embankment is cordoned off to
SF: Light blocks of around 20kg each, manner of installation, stability and prevent loading close to the edge.
packed in an open face checkerboard durability. Other factors can be whether it
pattern, are usually only good for walls is an open assembly configuration or close- HR: By far the greatest threat to quality
up to 1,5m. There are many block types fitting, interlocking configuration, hollow assurance in the industry comes from
and some are packed in a closed face with the option of being plant-supportive, “reverse engineers”, those who forego
configuration with no gaps between or solid. The engineer needs to make an the cumbersome process of designing,
them. The type of block used should come informed choice of block usage based on

Landscape SA • Issue 102 2021 19