Nestled against the picturesque slopes of the Tygerberg Nature Reserve; De Plattekloof Lifestyle Estate stands as a testament to innovative terracing. With breathtaking views of Table Bay; Cape Town City Bowl area and Table Mountain, this five-star retirement estate offers a wide range of accommodation; amenities; and care facilities.
Some of the retaining walls built with Terraforce L-12 Rock Face blocks, before planting by Intebe Landscaping
The estate’s sloping terrain
The estate’s sloping terrain has been converted into a luxurious living environment through the construction of some 2,300 m² of gravity walls using Terraforce® L12 and Decorwall blocks. The walls have not only created stable platforms – linked with staircases (Terraforce® 4×4™ Step blocks) and ramps – for the construction of elegant homes; apartments and community buildings; but have also carved out serene, verdant garden terraces.
With planting, the Terraforce walls have carved out serene, verdant garden terraces at the estate
Delivering striking aesthetic appeal and remarkable versatility, the success of De Plattekloof’s landscaping project was buttressed by the judicious selection of Terraforce Rock Face blocks in combination with the Decorwall blocks. Retaining garden walls were also built at the front of individual homes, in addition to the estate garden terraces.
The estate walls
The estate walls were built in three phases. Phase 1 began in 2016, and Phase 3 is still in progress. Wall heights, which were determined by the site’s natural topography and structural requirements, vary from 1m to 6m.
Wall heights, which were determined by the site’s natural topography and structural requirements, vary from 1m to 6m
The retaining wall blocks
The retaining wall blocks were supplied by Klapmuts Concrete, and Decorton Retaining Systems used them to build the walls. The latter were designed by Freddie Laker of iCOS Engineers cc and were landscaped seamlessly into the estate by Intebe Landscaping. This included selecting suitable vegetation to stabilize the slopes; enhance aesthetics and ensure long-term sustainability of the walls.
Built on a piled concrete beam, this L-12 Rock Face retaining wall supports a wheelchair path.
“One of the main challenges was adapting our design to the site conditions and switching from the originally specified L11 blocks to the lighter L12 blocks. Moreover, some walls were constructed using a cut-and-fill technology; while in others, engineered fill was used to build up levels. The latter of building up levels ensured proper compaction and stability.
Installed by Decorton Retaining Systems
“The foundations varied based on ground conditions, with some sections requiring reinforced concrete bases, while others were supported on existing concrete retaining walls. Some of the higher walls needed additional structural support in the form of starter bars and concrete infill to enhance their load-bearing capacity and improve overall stability; particularly in high-stress sections of the walls,” advised Laker.
A planted wall built with Decorwall blocks
SP van Blerk, managing director of Decorton Retaining Systems, said that geogrid reinforcement was placed at every second layer of block intervals.
4×4 Step Blocks integrate seamlessly with a Terraforce wall
Integrated steps
“This extended from 750mm on the lower walls to as much as 2,000 mm behind the higher walls. Geogrid reinforcement was introduced from a wall height of approximately 2,5 meters and above, depending on the specific engineering requirements.
Another Terraforce 4×4 Step block staircase on site
Drainage and irrigation
“Drainage was incorporated behind all walls, irrespective of wall height, to prevent pore pressure from building up behind the walls and ensure long-term durability. The drainage system included perforated pipes placed at the base of the walls, backed by drainage aggregate, and covered with geotextile fabric to prevent clogging. Weep holes were also integrated into the design to allow water to escape.
A Terraforce wall detail showing installed irrigation
“One of the retaining walls was constructed on a piled concrete beam. The wall, which supports the load of a wheelchair access ramp above it, required precise alignment and additional structural reinforcement to maintain long-term stability,” said van Blerk.
Terrafoce L12 blocks recently planted by Intebe Landscaping
Terraforce managing director, Karin Johns, says Terraforce blocks are designed to create one of the most energy-efficient segmental retaining wall systems.
“Being hollow yet strong, they require less concrete to do the job when compared to solid block systems. They are also plantable, and if an irrigation system is properly installed, a Terraforce wall can be completely covered in vegetation,” advises Johns.
Plants thriving in the Terraforce L12 blocks
Over 4 decades of experience
A Concrete Manufacturers Association (CMA) member for over three decades, Terraforce has maintained a strong foothold in the South African retaining wall market for over 40 years. During the past decade, the company has seen a steady expansion into the international retaining wall market with a footprint extending to Australia, Canada, Egypt, Ghana, India, Lesotho, Morocco, Namibia, Nigeria, Spain, Swaziland, and the United Arab Emirates.
Project Team
Engineer: Invictus Engineering Services
Retaining Wall Engineer: Fred Laker, iCOS Engineers cc
Main Contractor – current: Mastec Construction
Sub-Contractor: Decorton Retaining Systems
Landscaping: Intebe Landscaping
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