Exxaro Corporate Head Office Precinct Centre, Roger Dyason road, Pretoria West

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Condition Poor to Excellent
Date of origin 1962
Previous names Iscor Building/Yskor Gebou
Place Pretoria West
Street Roger Dyason road
Town Pretoria
Magisterial district City of Tswane Metropolitan Municipality
Province Gauteng
Country South Africa
GPS coordinates 25°46'40 S/28° 09'55 E
Planning authority name Iscor Corporation
Architect/Firm Iscor Building Committee
Project architect/Designer


David Ross

A.L. Meiring (Advising architect)

Commissioning owner Iscor
Current owner Exxaro
Current occupant Exxaro
Previous uses Iron ore mining administration building
Current use Coal mining administration building
Classification/Typology Industrial, Modernism: International style

“This huge Headquarters and Research Building of Iscor reflects the status of the Corporation as one of our leading industrial undertakings” – A.L. Meiring (Iscor, 1961:7)



" Places that are likely to be of significance are those which help an understanding of the past or enrich the present, and which will be of value to future generations." (Australia ICOMOS Burra Charter, 1999:12), serving as an example and prestige facility in being a leader in the mining industry nationwide as well as on the international market.

Exxaro Building Complex (Iscor) carries cultural significance in the form of architectural, aesthetic, social, technological and historical value. The earliest of the buildings of the Complex are only 53 years of age and therefor are not protected under section 34 of Act 25 of the National Heritage Resources Act of 1999.

The buildings are built in the International Style which is typically characterised with rectilinear forms; light, taut plane surfaces that have been completely stripped of applied ornamentation and decoration; open interior spaces; and a visually weightless quality engendered by the use of cantilever construction. Materials like glass and steel, in combination with usually less visible reinforced concrete are popular materials to this style. The style was also characterised by it’s emphasizing of the machine aesthetic, rational and modular design, and it’s use of curtain walled facades. The International Style is one of the many legs of styles of the Modern Movement.

Seagram Building -Mies van der Rohe-NYC1.jpg
Seagram Building, Mies van der Rohea
External facade.JPG
Exxaro North Block facadeb
Aerial view, Iscor.jpg

Aerial view of Iscor Headquarters 1963c

The Exxaro Building Complex bears remarkable resemblance to the Seagram Building in New York, designed by Mies van der Rohe in 1958, which was built exactly around the same time as the Exxaro Buildings (Iscor Buildings), also in the International Style. (http://www.britannica.com/EBchecked/topic/291280/International-Style) Thus it may be safe to say that the Exxaro Building Complex is one of South Africa’s leading examples and versions of the International style and machine aesthetic from the 1950’s. The architect of the Exxaro Precinct is David Ross, but very little is known of him. The advising architect on the design of the buildings was A.L. Meiring, who indeed was well-known. He was the Head of Department of Architecture at the University of Pretoria from 1943-1966, at a period of time when well-known architects were graduating under him like Karel Jooste, Gawie Fagan, Hendrik Boogertman (father of Henk Boogertman who would later do alterations on the Iscor Building in 1995), and Hans Wegelin (http://www.artefacts.co.za/main/Buildings/gradframes.php?school=368&orderby=dategrad) . The buildings are excellent examples of a typology that had a direct connection to a broader International Style while in pursuit for an architecture that represented Iscor’s image as well as a new Afrikaans culture.

The Iscor Buildings were the first in 1959 in South Africa to be constructed alomost completely out of steel, and set quite a benchmark for technology and the construction with steel in South Africa at the time. Up till then steel construction was an anomaly, as most buildings in South Africa followed the Beton Brut style which became popular at the beginning of the Modernist style, and was further popularised by Le Corbusier in the 1940's. (http://en.wikipedia.org/wiki/Brutalist_architecture%22%3Ehttp://en.wikipedia.org/wiki/Brutalist_architecture)

The Buildings consist of a steel skeleton skeleton, which was quite high-tech for the time. The facade consists of both vertical and horizontal steel members which create a modular design on the facade. The use of steel as well as the unique design of the facades of the buidlings were done in order to communicate Iscor's progressiveness in its line of business, as well as to portray its modernist corporate image.

Exxaro’s Headquarters overlook a beautiful hill on which the Voortrekker Monument rests towards the North East. It is positioned on a picturesque landscape itself, being slightly elevated on a hill making it a visible landmark side-by-side the Voortrekker Monument towards the western side of Pretoria. It’s position is iconic, as well as its features as mentioned above. Many a young army lad, recall being sent out for an early morning 50km run from the Valhalla army base, around the Iscor grounds and ‘wagon wheel’ traffic circle when most of the roads were still dirt roads, and back again on ‘special celebration’ of Paul Kruger’s Birthday on 10 October.(2)
The Exxaro Building Complex can be seen as a manifestation of modern thinking in South Africa. The physical building together with the intangible heritage further contributes to the spirit of the place which makes the building and its setting unique.

Exxaro Buildinds have the potential to serve as a precedent upon which a continuity of International Style theories might be discovered for the future.


Current known heritage status

The structures on the site have not reached an age of 60 years yet and therefor they are not protected under section 34 of the National Heritage Resources Act (NHRA) 25 of 1999.

NHRA does require though that under section 38, Notification of Intention to Develop, must be made to the necessary authority where the intention is to do "any development or other activity which will change the character of a site—(i) exceeding 5 000 m2 in extent” (NHRA, section 38-1). The act also states that any structure with “cultural significance’’ which refers to “aesthetic, architectural, historical, scientific, social, spiritual, linguistic or technological value or significance”, should be protected.

The buildings and site have quite a lot of significant value, which is referred to in the Significance of the site.

During October of 2012, a heritage assessment report was done by heritage consultant for alterations to be made to the Exxaro Corporate building, Nicholas J Clarke. The following assessment of current heritage value was established for the building in the condition that it is currently in 2012. (Clarke, 2012:3)



Possible interested and affected parties

                                                                                                                                                                                                                                                                              Descendants of A.L. Meiring (Head of Department of Architecture at the University of Pretoria from 1943-1966) (1)

Arcelor Metal South Africa (Iscor iron-ore mining company under new company name) Nicholas Clarke (Heritage consultant on new development of Exxaro Corporate building for 2015, and lecturer at the Department of Architecture at the University of Pretoria)

Boogertman and Partners, Pretoria (Architectural firm previously involved in alterations on Exxaro(Iscor))

Future occupants of old Iscor Building, new Exxaro Corporate Centre Building

Exxaro staff and visitors


In September 1939 when the Second World War broke out in Europe, countries like South Africa was called upon to assist Brittain in its war struggle alongside Norway, France and other lower-down European countries. By the start of the war, Iscor was producing 345 000 tons of raw steel per year. When the war ended, the production had increased to 520 000 tons of raw steel per year. The steel produced during this period would be mainly used for ammunition. (Iscor, 1953:147,148) After the war, one of Iscor’s largest quarters was built in Vanderbijlpark due to the sudden increase in demand for steel, and was completed in 1952. Iscor now rented small buildings in Pretoria from which steel production and administration would be run, as well as a large factory in Vanderbijlpark. Greater demand for steel, meant greater amounts of employees, and soon Iscor would have to make their most crucial but most rewarding decision since its existence. It was decided to build a headquarter for this iron and steel giant, which would in the future serve as beacon on entering Pretoria from the south western side. (Iscor, 1963:7)

More than 3500 ton of steel would be used to construct the new Iscor headquarters. It’s location would be one of the most picturesque sites south west of Pretoria, on a then open landscape, about a kilometer from the Voortrekker monument. (Iscor, 1963:3) When the project was under consideration, Iscor’s board of Director’s made a decision that only steel and other materials manufactured by Iscor would be used for as far as possible in the construction of the new buildings. The design of the headquarters was run by Iscor’s in-house architectural section, with the South African Institute of Steel Construction Limited assisting with plans for a building framework made entirely of steel. The main architect on the project was David Ross, an employee of Iscor at that stage. (Greig, 1971:207) Very little has been recorded about David Ross. Part of the architectural team was Advisory Architect, A.L. Meiring, who at the time was head of Department of Architecture at the University of Pretoria. The project in its entirety would be under control of a Building Committee nominated and appointed by the board of directors of Iscor. (Iscor, 1963:3)

The landscape on which the new building would be constructed, was a wild landscape with aloes, wild grasses and many other indigenious plants growing on the 'koppie' opposite to that of the prestigeous Voortrekker Monument. Close to the new site, was a traffic circle referred to as 'the Wagon Wheel', which would be an iconic feature in conjuction with the new Iscor building. (Clarke, 2012:16)

Exxaro Plan.jpg

Plan of Exxaro (Iscor 1963)d

The building would consist of a Northern block, a Southern Block, and a Research Block. After ground work had taken place, the construction of the building formally commenced on 16 November 1959, and less than two years thereafter, on 9 November 1961, the first part of the South Block was completed. (Iscor, 1963:3). The Research Block was to be completed by April of 1962. (Iscor News, 1961:18) The official opening of the new Iscor Headquarters Building happened on 28 February 1963. (Iscor, 1996:24) In total a number of 5 main buildings with many outbuildings were built. Between 1964 and 1965 Iscor added a research laboratory to the precinct. (Clarke, 2012:3) Hereafter minor maintenance work was done on the building from time to time, and only in 1995 and until 1996, the main facade of the South Block building was altered by an architectural firm local to Pretoria, Boogertman and Krige. After this the precinct undergone very little further changes.

In 2001 Iscor was unbundled registered as a company, Kumba on the JSE. In 2005 Iscor changed its name to ArcelorMittal. After the unbundling, all of Iscor's resources, successes as well as the Iscor Headquarters Building became that of Kumba's. In 2006 Exxaro was formed after an empowerment transaction involving Kumba Resources Limited, Anglo American plc, the Industrial Development Corporation and Eyesizwe Mining (Proprietary) Limited. (http://www.exxaro.com/content/about/historybeginning.asp%22%3Ehttp://www.exxaro.com/content/about/historybeginning.asp)

Under new ownership of Exxaro, the company requested in 2012 that further alterations be made to the precinct in order for the building to communicate the company's environmentally friendly outlook and practises. Their aim is to with the alterations get a green star rating of 4 stars. (Clarke, 2012:4)


Description of alterations with dates affected

Most of the Iscor Headquarters building blocks were fully completed by 1964. After which a research laboratory was added to the Complex and completed in 1965. The buildings stayed mostly the same until 1995 and 1996, when then architectural firm, Boogertman and Krige (B+K), was commissioned to design alterations for the main entrance of the South Block, as well as the interior. Iscor’s brief to B+K emphasized the need for a new facade which would project an image of Iscor being a successful 21st century leading global steel producer.

South Block Facade.jpg

Exxaro South Block, facade alterations by B+Ke

South Block Facade, front elevation.jpg

Exxaro South Block, front elevation, alterations by B+Kf

South Block, interior gardens.jpg

Exxaro Interior planters, between original South Block facade and newly added facade by B+Kg

Boogertman and Krige’s idea was to design a facade which would complement the original modernist building, in adding an extension which would in 20 year’s time still be suitable to the building and tell their story of success. (Building, 1997:20) The new additions would be lead by architect Solly Venter from Boogertman and Krige. (Building, 1997:69) On the North facade of the South Block, a free floating curvilinear glass wall with a stainless steel framework standing away from the building was designed and built. The glass structure stands completely separate and independent from the original building, and is only attached to the original building’s structural steel columns by angled springplates at the top of the glass wall. (Building, 1997:69) The idea that B+K tried to achieve with the new curved facade, was to soften the linear, angular, and cubistic appearance the then current northern facade. (Building, 1997:64) The new glass facade uses a glass fixing system which allows for a flush glazed wall. The glass panels are fixed by means of four counter sunk bolts on the four corners of each glass panel, fixed to light steel frames on the inside of the building The glass wall frames the reception and a number of small restaurants, which was also redesigned by B+K. (Building, 1997:69) Along with a new facade to the South Block, a number of magnificent water features and planters, were added to both the exterior as well as the interior. A visually stunning portico-like steel roof structure was added along with the glass wall to the northern facade of the South Block, where client arrivals would be. (Building, 1997:64) This roof structure runs all the way along and over the impressive stairway leading up to the entrance lobby of the building. To the north-eastern side of the South Block, B+K also added a gym amongst other facilities. (Building, 1997:65) During all of the alterations made by Boogertman and Krige, materials such as stainless steel, glass, marble, ceramic tiles, and natural slate, were added to the existing building with most of its features built out of various types of steel. (Building, 1997:63) Several service areas were also added by Boogertman and Krige, such as kitchens, cold rooms, food storage, five dining rooms, a staff canteen, and managerial dining facilities. (Building, 1997:66) The managerial dining facilities, on the third floor of the building, are enclosed behind a glass curtain wall which mimics the curved outer northern facade of the South Block, and in effect creates an east-west passage between the facade and the curtain wall, and it is within this passage that the interior fountains, water features and planters are placed. (Building, 1997:67)

The interior of the original complex existed out of mostly open-plan office space, but over time has been partitioned off.(Clarke, 2012:15). The original interior consisted of acoustic ceilings made entirely of perforated steel with slagwool for acoustics, which was a by-product of Iscor's steel smelting at the time. All the doors to offices were also steel, along with partitions and acoustic partitions which was also perforated with slagwool inside of the partitions. (Iscor, 1963:3) In the meantime most of the ceilings in the building have been replaced by acoustic gypsum suspended/drop-in ceiling boards. Many of the doors have also been replaced by wooden hollow core doors. Partitions have been replaced by more modern versions of light-weight movable partitions. Slagwool, used for acoustic purposes have been replaced by more current acoustic solutions, and many of the original floor finishes have been replaced over time with ceramic floor tiles and new carpets in office spaces and meetingrooms.

Currently, the curtain-wall façade of the all the buildings are about 53 years old. Since it was originally completed in 1963/64 the physical decay on the building has been quite extensive. Poor detailing on the facade has also lead to many leaks. (Clarke, 2012:1)

Under new ownership of Exxaro since 2006, it has been decided to upgrade the building to meet the company's image as well as requirements for a more environmentally-friendly building, while still retaining the original features iconic to the building. The current facade as is since 1963/64, and after alterations in 1995/96, also does not comply to current environmental standards with regards to thermal mass, daylighting, effective ventilation, and fire standards, all the more reason to Exxaro to be altered (Clarke, 2012:1). 

Description of site and/or structures and/or interior spaces

The old Iscor building, now Exxaro, is located on the farm Groenkloof 358/Portion 70, on the corner of Roger Dyason and Voortrekker roads, Pretoria West. The old Iscor building, Exxaro building, is designed in the International Style, which at the time made perfect sense in alignment with Iscor's post-war increase in international status. The International style is known for the following characteristics: rectilinear forms, light, in tension planes that have been completely stripped of appornamentation and decoration; open interior spaces; and a visually weightless type of construction. Typical materials that were used were glass and steel, in combination with reinforced concrete for slabs within the building.(http://www.britannica.com/EBchecked/topic/291280/International-Style) The International Style emphasized the Machine Aesthetic of the twentieth century with modular rational design as well as proportioned curtain walled facades.(Clarke, 2012:6) One well known International Style building is the Seagram Building by Mies van der Rohe, which the Exxaro building bears remarkable resemblance to. The choice of International Style for the Exxaro (Iscor) building also spoke of the company's line of business, that of the mining of iron-ore for the manufacturing of steel. (Clarke, 2012:7) More than 3500 tons of steel was used for the construction of the building complex. (Iscor, 1963:1) The choice of using steel for the construction speaks of the modern, forward-thinking, and corporate identity that Iscor wanted to portray as future steel manufacturing company with its iconic building as both a national and international landmark. (Clarke, 2012:7)

The grounds on which the building is built is about 12.1406 hectares, stretching from the the western side of Pretoria to the Voortrekker road and Roger Dyason road crossing, which used to be known for the iconic 'wagon wheel' traffic circle at this intersection. (Iscor, 1963:1) The whole building is designed to be a harmonious whole with the hill on which it is built. Before construction of the building in 1959 it was decided on an open-type layout, in order to eliminate any courtyards from forming inbetween the buildings, and in essence created buildings which only face either North or South. (Iscor, 2012:1) The building complex runs on an East-West axis. Only steel and other products that Iscor manufactured during the 1950's were used as far as possible in the construction of the building. The entire building complex has a total floor area of 33724 square meters. (Iscor, 1963:1) The use of steel had to be emphasized in order to communicate the area of business of Iscor. The building consists of stainless steel window frames, posts, and mullions. The building is built with steel cross bracing to provide stability to the structure. The facade of the buildings is constructed of steel ribs in modular positions, in order to, along with horizontal steel beams, create the rational design of the curtain wall facades of the buildings. (Iscor, 1961:9)

In the interior some of the removable partitions are made of steel, and some of the acoustic partitions originally had slagwool inside of them (replaced by modern acoustic solutions), which was one of the by-products of Iscor's steel manufacturing in the 1950's. The interior was designed to consist of modules of 1200mm in order to allow for modular placing of partitions. Currently, interior layouts and positioning of partitions don't obide to the modules any more. Some of the acoustic ceilings consist of perforated steel sheets and originally also had slagwool above it for the absorption of sound. Today most of the slagwool has been replaced by more current acoustic solutions. The floors are finished with uniform floor tile and linoleum tile patterns, with carpets in some of the office areas and meeting rooms. (Iscor, 1963:3) Where Boogertman and Krige made their interventions in 1995/96, some of the floor finishes were replaced by ceramic, marble and slate floor tiles, especially in the current reception area. (Building, 1997:65) Some of the doors are steel doors, as was in the original building. The complex consists of a South Block, where the reception is currenlty, along with many boardrooms and meeting rooms and service rooms, a North Block with office spaces, a Research Block, an Auditorium Block with an auditorium which can seat about 208 people (Iscor, 1963:3).











1. Timeline: Department of Architecture, University of Pretoria, 2011. Available at <http://www.artefacts.co.za/main/Buildings/articles.php?artid=388>, accessed 7 October 2012.

History. [Online]. Available at: <http://www.exxaro.com/content/about/historybeginning.asp>, accessed 10 October 2012

International Style. [Online]. Available at: <http://www.britannica.com/EBchecked/topic/291280/International-Style>, accessed 20 October 2012

Brutalist architecture. [Online]. Available at: < http://en.wikipedia.org/wiki/Brutalist_architecture>, accessed 7 October 2012

Department of Architecture graduates. [Online]. Available at: <http://www.artefacts.co.za/main/Buildings/gradframes.php?school=368&orderby=dategrad>, accessed 7 October 2012


Iscor. 1996. A humble beginning. Iscor News Commemorative Edition, July:24

Iscor. 1953. Time of was. Steel in South Africa. pg.147-149. Pamphlet

Iscor.1963. Hoofkwartier van staal. pg. 1-7. Pamphlet

Iscor. 1961. Iscor News. December, vol. 26:18

Iscor.1961. Iscor News. July, vol.26:7-9

 Unknown. 1997. Alterations and additions to Iscor's head office. Building. April vol. 59:62-69
 Unknown. 1997. Iscor head office: New facade. Building. June vol 60:20-21
 Clarke, N.J. 2012. Cultimatric CC (heritage report).


Greig, D. 1971. A guide to architecture in South Africa. Howard Timmins: Cape Town


2. Oosthuizen, J.H. 2012.


Corner Roger Dyason road and Voortrekker road, Google maps

a. Seagram Building. [Online]. Available at: < http://www.tripadvisor.nl/LocationPhotos-g60763-d312023-Seagram_Building-New_York_City_New_York.html >. Accessed 7 October 2012

b. Oosthuizen, J. 2012. Exxaro Corporate Head Office Precinct Centre. 6 October 2012

c. Iscor.1963. Iscor Headquarters aerial photo. Hoofkwartier van staal. pg. 1-7. Pamphlet

N.J. Clarke, 2012. Heritage Assessment Table. Cultimatrix Report

d.Iscor.1963. Plan of Iscor. Hoofkwartier van staal. pg. 1-7. Pamphlet

e.Unknown. 1997. South Block facade (alteration). Alterations and additions to Iscor's head office. Building. April vol. 59:62-69

f.Unknown. 1997. South Block, front elevation. Alterations and additions to Iscor's head office. Building. April vol. 59:62-69

g.Unknown. 1997. South Block, interior gardens. Alterations and additions to Iscor's head office. Building. April vol. 59:62-69




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