Silo 3 and 4

No. 3 Silo consists of three independent apartment towers containing 79 high end apartments over 11 floors. The three towers are connected by two steel framed lift and stair cores enclosed in expanded aluminium mesh, providing spectacular views of the harbour and V+A precinct.

Silo 4 essentially forms the base for the apartment towers and contains an upmarket gym facility over two floors. A double volume pool pavilion faces onto Silo Square, with panoramic views of the new Zeitz MOCAA Gallery, Silo Hotel and surrounding Silo District public spaces.

Expressed materiality and appropriate detailing were considerations equally as important as resolving the functional and programmatic requirements of the brief.

The character of the building was developed as an interpretation of the inherent “gees, (or ‘spirit’), of the precinct as part of a working harbour. In response to the surrounding built environment, the team explored further the themes of ‘fit for purpose, working harbour elements’, and in its making exploited the possibilities of composite structures – concrete and steel working together – in order to maximise the clear floor to ceiling dimensions of the apartments. Concrete up or downstand beams were entirely avoided in order to maximise the views out all of the Apartments, bearing in mind the overall height restrictions imposed by the Planning regulations and consents achieved. Furthermore, in order to construct the expansive floor plates, without resorting to more concrete columns and beams, steel framing ‘tied back’ to the central shear concrete cores, is used to assist in accommodating the floor plate cantilever. This ‘additional steel’, has been consciously ‘picked out’ in colours referencing the cranes and other elements of working machinery in the surrounding dock yards.

The cast-in load bearing steel frames primarily consist of 50mm diameter solid carbon steel bars, adjustable custom reverse thread couplers, welded up 230×90 PFC frames, 203x203x46 H columns and intricate welded end plate connections. Solid bars were chosen for the high tension capacity with minimal lengthening when fully loaded and the custom couplers were chosen to allow for tolerance and future adjustability. The Virgin Active steel roof structure is made up of PFC girders and trusses with solid round bar cross bracing. The exposed round bar cross bracing aesthetic was followed through on the external steel stairs, steel lift shaft structures and the external walkway bridge.  

The installation and sequencing of the load bearing steel frames were by far the greatest steel related challenges faced on site. These frames were designed to work compositely with the concrete structure resulting overall in a more slender structure. These frames were installed concurrently with the concrete structure which impacted on sequencing of slab construction, post-tensioning and temporary backpropping. The interface between concrete and steel required works to be highly accurate to achieve the desired aesthetic of exposed steel and raw concrete as well as work compositely as intended. Communication and co-ordination between the architects, structural engineer, main contractor and steel sub-contractor early on in the project was instrumental in achieving this.

The steel components used throughout the building are integral to the building’s structural integrity. This is expressed through the bold use of colour, further highlighting the key ‘elements’ in the structural assembly. Yellow is used on the façade steel elements that support the cantilevering balcony concrete slabs, while red highlights the two circulation cores connecting the three towers.

Cladding materials, including Rheinzink and perforated metal panels were also selected to respond to the harbour industrial shed aesthetic.

The collaboration of consultants, contractors, sub-contractors, specialist advisors and client was integral to the successful completion of No.s 3&4 Silo.

Revit was used as a production tool by all consultants (as was required by the client), and allowed the sharing of a central digital model across all disciplines.

Tons of structural steel used 320.392
Structural profiles used Solid bars, PFCs,H & I sections, angles, cold formed lipped channels

Project Team

Project Team Role Company
Nominator Sutherland
Client/ Developer V&A Waterfront
Architect VDMMA & Makeka Design Lab
Structural Engineer Sutherland Engineers
Quantity Surveyor MLC
Project Manager MACE
Main Contractor WBHO
Steelwork Contractor LJ Le Roux Industries
Steel Erector LJ Le Roux Industries
Corrosion Protection
Advanced Galvanizing
Corrosion Protection
Paintwork Contractor
MRH Group
Photographer, Photo competition VDMMA

If you were a part of this project, and your company details are incorrect or missing – please notify the SAISC so that the error can be corrected.

House Matthews

In 2014 Colin Matthews, owner of Mercury Steel construction, had a vision to build his dream home in Helderfontein Estate, Fourways on the Jukskei river banks. The majority of the home was designed to reflect his passion for steel, both structurally and aesthetically.

Mercury Steel was a reputable company doing most of its steel work for Century Property Developments for the last 20 years, with a turnover of R25m a year in the residential market. They’ve won awards in galvanised steel construction and been a pillar in the design and execution of many Century buildings within their developments.

Sadly, Colin passed away in January 2017 leaving the house with only the structural steel skeleton complete. Richard Wands and Jessica Hofmeyr, who owned the neighbouring stand, purchased the stand with completed structure from the deceased estate and selected Century Property Developments to complete the house in honour of Colin Matthews.

The brief to the architect was to ensure that steel remains the dominant element in the design, creating strong features yet also a light quality due to the slabs and walls sitting within the webs of the I beams. Externally, the use of steel is dominant and aggressive, with massive beams and columns. In the interior, steel is forever present, but subtle and discreet where the beams form part of the floor finish, the soffit and the walls. Steel enables a lean design and removes the obstructiveness of large brick / concrete columns and beams, which would otherwise be required for all the large openings. The steel allows natural light to enter the house and exposes the home’s magnificent view.

Structurally, the house consists of 3 floors and the structural frame was designed and built mainly with 254×146 x 37kg horizontal I Beams to carry the middle and upper level exposed concrete suspended slabs. The larger beams enable the suspended slabs to sit perfectly in the web of the steel beams. 152 x 152 x 37kg vertical H Columns allow the brickwork to be flush and the windows to sit neatly within.

The roof structure’s top frame is constructed with 203 x 133 x 25kg I beams with the rafters being steel IPE 160 sections. Purlins consisted of 150 x 65 x 20 x 2.5 CFLC sections tying the structure together.

Cantilevered balconies are supported by 160x80x3 RHS columns running down the front of the house on an angle, creating a top-heavy cantilevered look, with the house seemingly on stilts.

The gables and the garages were cladded with Safintra Trimflute Sheeting. The requirement for the cladding to sit flush with the 254 I Beam steel outer flange meant we had to use a 140mm cement brick to allow for spacing, and the battens needed 20mm square tubing.

From the driveway to the bottom floor, the site has a 7m fall, making access extremely difficult. Steel sections had to be placed by a crane sitting on the top level. The steel frame ensured that the building was plumb and square, which then made setting out walls and leveling slabs etc. easy to achieve. Ensuring that services all ran in the concrete slab and into the walls – without seeing any of the conduits – was a challenge and holes had to be drilled through all the internal horizontal beams to allow for water, gas and electrical piping. These areas had to be strengthened with structural fins within the steel web. Outer walls had to be built with the outer brick laid flat and the inner brick on edge, to ensure that the plaster didn’t protrude beyond the steel internally. This resulted in a clean finish, with the edges of the I beam flanges being flush with the plaster.

Regular meetings were required early on to mitigate challenging details which could not be foreseen in the planning stage. The Contractor, Engineer, and Architect were constantly involved to ensure that the building could function structurally and aesthetically without compromising the look of the steel or any other part of the house.

A challenging project indeed, but very rewarding and evident in the final product.

Thank you for considering the possibilities that steel in a domestic setting offers, both structurally and with very pleasing aesthetics.

Tons of structural steel used 21.396 Tonne
Structural profiles used I – 254x146x37 / I – 203x133x25 / H – 152x152x37 / Ipe 160 / Cflc 150x65x20x2.5 / Rhs 160x80x3


Cladding profile/ type used Safintra Trimflute – Colour Thunderstorm
Cladding area/ coverage and tonnage 208m2 / 1.04 TONNE

Project Team

Project Team Role Company
Nominator Century Property Development
Client/ Developer N/A
Architect Studious Architects
Structural Engineer C-Plan Structural Engineers (Pty) Ltd
Engineer C-Plan Structural Engineers (Pty) Ltd
Quantity Surveyor Century Property Development
Project Manager Century Property Development
Main Contractor Century Property Development
Steelwork Contractor Wrought Iron Factory
Steel Erector Wrought Iron Factory
Cladding Manufacturer Safintra (Pty) Ltd
Cladding Supplier Safintra (Pty) Ltd
Cladding Contractor Nico Grobler Dakoprigting
Photographer, Photo competition Nextgen Group (Pty) Ltd
Photographer, Other submitted images Nextgen Group (Pty) Ltd

If you were a part of this project, and your company details are incorrect or missing – please notify the SAISC so that the error can be corrected.

House Eagle Heights

What is the purpose of the structure/ project?

The steel trusses of the roof was designed to enhance the aesthetics of the building, bringing in softer lines. The roofs themselves are broken up, to mitigate the massive bulk of the building and to accentuate the various space within. The roof is not only experienced from the outside, but also from inside, where the steel trusses makes it possible for the ceiling to sit flush with the steel, without additional cross bracing or support.

What was the brief to the architect?

The majestic house rises up from a beautiful portion of land with views in all directions. The soft curves of the building as well as the material palette allows the building to gracefully blend into its surroundings. In order to ‘fit in’ the extensive accommodation list the client presented us with, we had to utilise a basement, stretching almost the entire footprint of the stand, to accommodate some of the exciting features of this residence.

Was the project envisaged in steel from the start? If not – why was it built in steel in the end?

The steel was the most obvious solution for the roof in particular from the start

Give a brief description of the structural framing. What type of sections were used (e.g. hollow, cellular, I beams etc) and why?

The trusses are made up of I-beams, some curved and welded in the middle to form the apex of the roof. The purlins are lipped channels. The columns are mainly round steel columns to support the upper level slabs, and bridge.

What is special/ unusual/ innovative/ aesthetic about the steelwork/cladding in this project?

To create the curved roof, non standard truss design had to be employed. The trusses were made up specifically, with each of the roofs that have a slightly different span.

How did the project team work together (e.g contractor involved early, challenges/ ease of communication etc.)

The project manager ensured that the team was fully informed and worked well together. Additional specialists eg. roof sheet specialists were consulted from the start, to ensure that the project could be executed as planned.

Tons of structural steel used +- 6 ton
Structural profiles used Chanels, Lipped Chanels, I-Beams
Cladding profile/ type used ZincAlume Kliplock 700 Sheet
Cladding area/ coverage and tonnage 560sqm (includes roof sheeting)

Project Team 

Nominator Strey Architects and Associates (Pty) Ltd
Architect Strey Architects and Associates (Pty) Ltd
Structural Engineer PVA Consulting Engineers cc
Project Manager Earthstone Properties
Main Contractor Earthstone Properties
Steelwork Contractor Gert Visser Staalwerke
Steel Erector Gert Visser Staalwerke
Photographer, Photo competition Strey Architects and Associates (Pty) Ltd
Photographer, Other submitted images Strey Architects and Associates (Pty) Ltd

If you were a part of this project, and your company details are incorrect or missing – please notify the SAISC so that the error can be corrected.