In 2022 the UCL Company, leaders in the sugar, wattle and timber industry in the KZN Midlands, branched out into the fruit growing and packing industry by commissioning their project team to design and implement a unique facility near the town of Dalton. The facility, a sophisticated packhouse, was to bring their supply chain in line with the highest global standards.

Typically packing facilities are designed to accommodate a single commodity, or at least similar ones, which was not the case for the UCL packhouse. Rather, their brief was to pack both avocados and kiwis in the same facility, which led to them creating very specific protocols in terms of product flow and refrigeration solutions to suit both commodities in the same facility.

The case study involves the intricate use of both structural steel framing and also demonstrably uses Safal Steel’s high tech Colorplus^Ⓡ AZ150 coated steel in colour Thunderstorm with our bespoke Textured finish.

The roofing and cladding was installed expertly on site by MJC Industrial, which was rolled by Safintra into long roofing sheets on site in their profile Saflok^Ⓡ 700, to specified precision.

According to project architect, John Carter from Bespoke Architects: “The roof was curved and covered with Colorplus^Ⓡ AZ150 TCT 0.53 in Thunderstorm Textured. It was  designed around the sheeting material and profile properties to achieve a self-sprung curvature on the apex of the roof to reduce the total building height.”

In addition, the form of the roof is enhanced by this curved apex feature, which blends with the context of the building in the rolling landscape of the Midlands, say the designers. .

“All steel side cladding was also Colorplus^Ⓡ AZ150 TCT 0.53 in Thunderstorm Textured, this time roll formed into Safintra Trimflute^Ⓡ profile, colour to broad flute, to allow the fixing of the sheeting to the girts to be done inside the inverted rib and against the purlins.

“Because the fixing is a pierced fix, this methodology allowed a more securing fixing method, that hides the fastener head to a degree on the elevations”, Kriel explained

Carter adds  that the site itself presented a number of unique challenges:

“Challenges started with the poor soil conditions, which is perfect for the sugar cane previously cultivated on the site, but not for construction. This affected the overall design of the building envelope and also the way the roof would be fitted.

“The combination of the significant slope of the site and its high clay content required the implementation of a raft foundation”.  The raft foundation was a solid concrete slab that provided the contractors a solid base to work from overheard. Supporting the full weight of the packhouse, this raft foundation influenced the way the support  columns were designed and erected.

Carter says that the interior of the building required the accommodation of several microclimates depending on the nature of the operations performed in that section.

The first microclimate was ambient space, in this case, for receiving fruit and packaging materials. They did not need to be temperature controlled. In these areas, a typical combination of roof sheeting with a radiant barrier and side cladding was sufficient.  As mentioned above, the  cladding was Colorplus^Ⓡ AZ150 TCT 0.53 in Thunderstorm Textured  rolled into a Trimflute^Ⓡ Profile by Safintra. This was uniformly all applied to all exterior walling where the design required steel.

But it was the actual produce packing area that required a unique solution to accommodate  the the specified temperature-regulated environment, which also needs to allow natural light into the building in both the summer (for kiwi) and winter (for avocado) seasons.

Due to sometimes extreme summer and winter conditions, the Colorplus^Ⓡ-induced solution was bespoke. “A composite roofing solution of concealed fix sheeting Saflok^Ⓡ TCT 0.53 AZ150 from Colorplus^Ⓡ Textured above rigid roof insulation installed in between purlins. This design was combined with a polycarbonate panel that was applied vertically on the north elevation to allow natural light into the space while maintaining a controlled temperature internally”, he adds.

Jean-Jacques Kriel, founder of STANCE Consulting Engineers and structural engineers on the project expands further on the unusual roof design at the UCL Packhouse.

The roof shape is not standard and not covered in local building codes, rational design principles were used to model a complete 3D structural model of the building to aid in economising the steel tonnage of each square meter.

According to Kriel, this was no ordinary roof, but in the end, the project team were able to meet the requirements of the client and the client ‘was very happy’.

Kriel explains that the strict design maxim form should follow function, meant that a lightweight yet accommodating roof structure was needed. This was implemented by specifying the use of lightweight steel roof cladding as mentioned.

“The return on investment for such a facility requires it having optimal flow for interior operations. Therefore, columns should not limit the function and flow required of the floor of the packhouse.

“Therefore, a lightweight large spanning structure with minimal columns was indicated by the design. When absolutely necessary in terms of the load, columns were placed in strategic positions in line with fixed functioning features such as separating walls or next to stationary sorting machines”, he adds.

The roof ultimately consisted of a grid structure that accommodated differing span rhythms and still supported the vast array of suspended services. Adding to its complexity, the mix of cold room functions with high racking systems, within the building envelope, required the building height to be stepped to suit.

This design created vertical faces that needed to handle horizontal wind loads at height. To counter these,the roof shape in the main span direction was smoothed into a large radius parabolic shape. The mezzanine level also had a role to play in structural stability. It was sequenced in such a way as to assist with handling of the forces within the structure when the roof and vertical cladding was installed.”So the mezzanine was functional and comprised steel members and an unpropped shuttering system that could house the concrete floor forming it” he explains.

“A positive arising from this solution is that the parabolic shape added to the building’s context by respecting and thus fitting into the rolling hills of Dalton. From a functional point of view, it greatly benefited the structural engineering of the building by reducing the localised wind pressures the building experiences along its span” he concludes.

Safal Steel’s unique Colorplus® Textured is suitable for all roofing profiles – concealed fix, tile-profiled sheeting and corrugated. It is recommended for roofing pitches greater than 10 degrees and should be used at distances greater than 3km from the sea.

In the case of the UCL Packhouse, the architects explained that the major role of the textured finish was to mask the appearance of  bagasse sediment arising from the sugar cane surrounding the site. Very few horizontal areas are left exposed; this is to prevent the accumulation of the begasse, which causes a building to age quickly, hence sloped surfaces are dominant in the design elements.

Additionally, Colorplus^Ⓡ Textured is a great finish to mask the effect of oil canning, the

wave-like distortion in the flat areas of metal cladding and roof panels especially where long roof sheets are fitted on a sloping site and also are curved. It is by nature a diffuse reflector of inbound sunlight, so is an excellent choice under such conditions.

• Safintra: Colorplus^Ⓡ AZ150 roll formed into Saflok^Ⓡ 700 to architect’s specification – roofing.

Plus Colorplus^Ⓡ AZ150 roll formed into Trimflute^Ⓡ to architect’s specification – sidewall cladding.

• Safal Steel: Colorplus^Ⓡ AZ150 TCT 0.53 Textured in colour Thunderstorm to roof – 14 000 m2 and cladding 2 000m2.

Owner/developer: UCL
Project manager:  Feroqs Consult
Project architect: Bespoke Architects
Structural engineers: STANCE Consulting Engineers- Structural and Civil   Engineering
Structural Steel – NJW Engineering
Roof Sheeting and Cladding – MJC Industrial Roofs
Steel Roofing Profiler: Safintra
Steel roofing: Safal Steel
Drone photography: STANCE & Alliance Consulting Engineers per UCL

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.

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