Due to stricter heritage building legislation in South Africa and an increasing move towards reusing existing buildings in line with the circular economy, heritage building refurbishments are becoming commonplace, along with adaptive re-use..

The repurposing of heritage structures and their conversion into modern usable buildings challenges design, especially when it comes to the substitution of construction materials, on a number of levels. These include the replacement of older materials of construction with modern, lightweight materials that also echo the heritage look of the original building.

Steel roofing is an exemplary product and a fine example of where licenced aluminium-zinc coated technology such as found in Zincal® and Colorplus®, can beautifully and sustainably replace tired, corroded and heavyweight galvanised steel materials. These modern materials provide longer life to the roof, reduce its load on rafters and trusses and on the building’s walls and provide excellent opportunity for architectural creativity – curves, colours and contours – all thanks to the wide number of design options they provide.

At the new Visitors Centre of the South African Astronomical Observatory, which gave its name to its host suburb of Observatory, Cape Town, the science of astronomy has been practiced in South Africa for over 200 years. The Observatory site in Cape Town gained National Heritage status in 2018, prompting a renewed focus on preserving its rich cultural, natural, and built landscape.

Hence, SALT Architects rose to the challenge of repurposing a very old Victorian-era typology pump house, originally used for pumping water from the weir in the Liesbeeck River for irrigation purposes. Over time, it had undergone various renovations and transformations, serving as a workshop, an educational centre, and most recently, in part as an auditorium. The brief of the client, the SAAO, was based on proposals for transforming the existing Victorian era pump house into a visitor centre for the SAAO.

According to van der Walt the brief given to SALT Architects was to transform the old building into: “Sufficient ablution facilities, a reception area, varying exhibitions spaces, and a dedicated room for housing an observation instrument known as a heliostat. All on a relatively tight budget”. The heliostat room section is covered with a concrete roof.

“We saw the transformation of the Victorian-era pumphouse into a Visitor’s as an opportunity to uncover and showcase the site’s layered meanings. The oldest and more significant portions of the building were approached in a delicate manner, yet with enough targeted intervention to ensure the long-term use of the building” he explains.

Of the approach to the building, Van der Walt adds: “The approach to the building is established along a newly landscaped axis that guides visitors directly to the original front door of the Victorian era building. Upon entering the space, one experiences the volume and intricacy of the main pitched roof with restored exposed rafters.”

Above these rafters in the reception is a striking rendition of flat aluminium sheeting over the trusses, fashioned intricately into a work of art that accurately replicates the night sky with small backlit holes. Above the purlins is a layer of Isoboard, then a foil-faced barrier, and a new Colorplus® corrugated roof above, as the crowning glory of the building.

The original roofs covering both the pumphouse and adjoining workshop building were fashioned from corrugated galvanised steel, which was in a considerable state of decay and disrepair.

Subsequently, in line with the adaptive re-use of the structures into a modern functioning building for visitors and astronomy presentations, while adhering to heritage architectural standards, the look of the former corrugated iron roof was duplicated by the use of of Colorplus® in colour Raincloud Matt as AZ150 TCT 0.47, which carries a 15 year warranty.

Elsewhere on the structure, a near-flat roof necessitated the specification of concealed-fix AZ roofing in profile Diamondek.

On the site, the architect says: “The quality is holding up well. We do not even consider cheap imports.”

Architects: SALT Architects
Structural Engineers: AVCON Structural Engineers
Contractor – building and roof: JV – Boshard Construction with Benchmark Builders
Corrugated steel roll-former: Safintra
Concealed fix roll-former: Youngman Roofing
Site photography: Gareth Griffiths (roof), JD van der Walt and Robyn Walker
(pre and post renovations plus site elevation plan)

Colorplus® in colour Raincloud Matt as AZ150 TCT 0.47 in profile corrugated.
Roll former: Safintra

Safal Steel is a licenced user of the highly respected 55% Aluminium, 43.5% Zinc and 1.5% Silicon coated steel technology from BIEC International Inc. The company is the first and only
licensed producer of this patented coating alloy in Southern Africa, which is used to manufacture the highest quality metallic and pre-painted coated steel used in roofing, cladding, and many other structural applications.

This coating on this product, Zincal®, protects the steel substrate in two ways: The aluminium part of the coating provides a tough physical barrier, while the zinc component provides sacrificial protection, also protecting the steel at the cut edges. The superior corrosive property increases the life of the steel core up to four times longer than that of conventional galvanized steel.

Colorplus® is the pre-painted variant of Zincal® and is available in a range of coating options including modified Polyester, Textured and Matt finishes. These meet the specifications called by the most demanding architectural and design challenges.

An additional huge advantage of Zincal® or Colorplus® is its lightweight nature when compared with typical galvanised steel. This lends itself to modern sustainable construction methods, promoting dematerialisation, lower transport costs, longer life in service and reducing the footprint of the building on the earth.

Safal Steel warrants its Zincal® and Colorplus® (colour coated steel) to have a service life (prior to perforation by weathering in the natural elements) from date of installation. Warranty periods are determined by Safal Steel and may vary according to project design and location. A Provisional Warranty may be applied for at project design stage; this warranty serves as a guideline as to the final warranty Safal Steel may issue on project completion. A Final Warranty application form may be submitted to Safal Steel by the roll former on project completion, requesting Safal Steel to issue a warranty for the specific material used on a specific project.

Look for the trademark. All Safal Steel prime material is branded on the backing coat – insist on Safal Steel material.

For any technical queries please contact Safal Steel and ask for the representative in your area.