A systemic approach to timber in the African context

by Arné Gunter, BIM director, Earthworld Architects

Speaking at the 10th Wood conference in Cape Town, Arné Gunter guided attendees through his company’s journey on their Future Africa Campus.

*ALL IMAGES BY EARTHWORLD ARCHITECTS

Future Africa is a trans-disciplinary collaboration campus that fosters collective research, fellowship and collaboration among the vast diversity of cultures and disciplines on our continent. Future Africa is not only about
place (locality, meaning) nor space (building), but also about the contribution a building can make to the ecology within which it is developed.

FACILITIES AND CONTEXT TO DESIGN

The facilities consist of:

• 280 one-, two-, and 3-bedroom living units;
• Four communal living and cooking areas;
• A crèche;
• Dining hall (Future Africa Hub);
• A research commons (administration and library); and
• Conference facility (250-seater auditorium; with two 50-seater multi-purpose rooms, and six break-away rooms, linked to the auditorium).

For the purpose of this article we will focus predominantly on the Hub, housing units and conference centre, and our process of building with timber.

Firstly, let’s contextualise our approach. In the past the building process was simplistic, there was a sense of comradery and fellowship, spaces were created through simple processes and good craftmanship.

We used to create by hand, understood our materiality and most importantly work in community – working as a system – something industrialisation has taken away from the sense of making. This idea
is something we tried to capture, this process of ‘making’, of ‘understanding’ and ‘fellowship’. Bringing back that sense of the vernacular in the building process.

Now, what does that mean in the African context? Our exploration of this process led us to discover the latent potential of local micro systems. Where there was a sense of the vernacular. This idea of community-based or unskilled labour systems; people being the pivotal point in the system. So why not take this mindset; build a system by combining high-level design with local resources and skills.

We drew inspiration from old systems and tools, where people were key to the success. We then combined that with the new technologies of today. What this allowed us to do is to disentangle the building which led to the concept of a parallel off-site manufacture and on-site assembly approach.

This meant we could work to extreme precision whilst streamlining the productivity through the use of various building information modelling (BIM) technologies. What this allowed us to do is exchange information between the different disciplines and collaborate more efficiently and with better understanding.

THE INSTALLATION PROCESS OF THE HUB

The Hub (also known as the dining hall) was our first attempt in the timber structure system on the campus. We collaborated with local timber suppliers and engineers, exploring the type of timber we would use, taking into account the structural integrity we needed but still satisfying aesthetical proportions.

Once we had our main structural material, we deconstructed the building into smaller systems, dividing them into; primary structure (main), secondary structure (roof and façade structure) and tertiary structures (furniture and joinery elements).

We focused on designing the systems so that elements could be broken down into smaller, more manageable elements. This opened up new alleys for the building to be built by a smaller network of local suppliers and artisans. Portals were broken down into small ‘puzzle pieces’ that interlocked with one another to form a complete portal.

Once our design was finalised, we proceeded to building a prototype for testing. Testing was done in a controlled environment at the University of Pretoria, South Africa, with the presence of the engineers and other consultants. We coupled a hydraulic jack to the ends of each portal edge and tensioned them towards each other to break point.

The findings of our test led us back to the drawing board and we redesigned the jointing system of the puzzle pieces. The interlocking joints were redesigned, and blind nut clamp connectors integrated into the connections. We then retested the structure and complied with the standards.

When we start the manufacturing process, the primary portal structure took 90 days of cutting (two days per portal), a total of 820 puzzle pieces and 45 days of assembly (one completely laminated portal per day), using approximately 1 920 blind nut fasteners to clamp the portals together.

The systems of assembly were also designed for elements to be easily manoeuvred and installed on site. Based on the these ‘small building components’ principles, this allowed us to use vehicles with trailers or a small flatbed truck for transporting.

When installation started, it merely came down to the correct sequencing. First the baseplate brackets, our main connections between structures. Secondly, we started erecting pieces into place, again making use of smaller equipment such as telehandlers and cherry pickers to place the portals correctly.

The portal had to be erected in two stages, first the short portals and then the larger portals followed, lifted into place and connected with steel brackets. The process of erecting the entire structure took approximately a month to complete.

When the primary structure was installed, we moved to the secondary structure. The roof, façade and ceiling structure. The roof structure was constructed using pre-cut and ready to fit on-site Laminated Veneer Lumber (LVL) beams with steel connector brackets. Façade elements being installed parallel to the roof structure installation, all elements contributed to the structural integrity of the building. Once the primary and first stage secondary structures were complete, we proceeded to final testing. The test conducted by the engineers consisted of suspending 950kg from the ridge, and 2 x 650kg from central points in the largest span area. The structure had to support the weight for three hours, without a deflection of more than 45mm. The structure only deflected by 5mm, and subsequently passed.

From testing we carried on with further installation of the secondary structure. These ceiling panels and façade structure were designed as clip-on elements to the primary structure (also being manufactured off-site and assembled on-site).

After the secondary structure was complete, and the building enclosed, we moved to the tertiary structure. This consisted of the fixed furniture and joinery elements in the building, also all manufactured off-site in six weeks and assembled on-site in a week.

HOUSING UNITS

The design of the elements in the housing units was developed to be pre-manufactured off-site during the construction of the primary concrete and brick structure, transported to site when the units were completed and installed on-site within a matter of hours. Elements that could be handled by hand, positioned in place and fixed.

We specifically developed new systems of modularity, through collaboration with local designers and manufacturers. This system allowed for furniture units to be adaptable, changing configuration to change the purpose of its use, or ease of replacement if a unit is damaged. Designs were also made to accommodate various configurations of included elements in each unit.

CONFERENCE CENTRE

The conference centre was our second attempt at a timber structure on campus, learning from our mistakes and improving our design. Once again we deconstructed the building into smaller systems, dividing them into; primary structure (main), secondary structure (ceiling and cladding structure) and tertiary structures (furniture & joinery elements).

What made this design different was that the building was laid out in a radial form, and there was a lot more integration between various trades. The manufacturing of the portal frames took approximately 54 days to cut (three days per portal), a total of 208 puzzle pieces and 18 days to assemble (one complete portal a day), using 900 blind nut fasteners to clamp the portals together. The structure was installed in just over one week.

The secondary structure consisted of a suspended acoustic ceiling structure and acoustic cladding. Each component was digitally manufactured, exported for cutting, assembly off-site and installed on site in a few days.

The ceiling structure was broken down into two sections. A substructure – we used a cabstrut system, normally used to suspend mechanical services in buildings and modified it to suit our needs. All the cables of the sub-structure were premeasured, digitally designed, built and installed ready to fix the acoustic elements.

Acoustic ceiling boxes – pre-manufactured boxes, complete with acoustic liners and insulation and a minimum 30% perforation achieved for acceptable acoustic values. Boxes that could easily be lifted and ‘clipped’ into place. It took four weeks to manufacture off-site, one week to install the sub-structure and one week to hang all the acoustic boxes.

CONCLUSION

In the end if we look back at our four-year journey on this project, we learned a lot about the process of off-site manufacture and on-site assembly. This concept allowed the development of systems to deconstruct a building into elements that allow for a systemic approach to construct (primary, secondary, tertiary) rather than the conventional methods. It also allowed us to combine this concept with the use of local unskilled labour and resources to develop these micro enterprises, so that they can take their place in the larger eco-system too.

Looking forward, we see that timber as material will be an influential part of these systems, given its characteristics and benefits and that these open building systems will augment micro enterprises, fostering collaboration, innovation and meaningful building on our continent and around the world.

The level of ownership taken on by the small contractors resulted in immense pride, meaning and a sense of accomplishment; traits that have been lost to our industry since the industrial revolution when labour was reduced to commodity.

In future, we hope to see the augmentation of these micro enterprises, funded by community banking; setting up new, small factories, utilising digital tools to innovate, collaborate and push the boundaries of these open building systems.

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