The original Backpackers at Afriski was built with shipping containers as they seemed appropriate for the low cost, weather proof, indestructible and quick accommodation qualities at the time.
With the extended & reworked Backpackers factory manufactured modular units called Modul8 was built in Gauteng in a controlled environment & then transported to Lesotho & placed on a prepared soil platform. A steel ring beam at the top & bottom, together with square steel posts act as a rigid frame which can be picked up from the top to load on a truck, transport to site & dropped off on a pre-prepared foundation (a soil mattress platform in this case). The smallest possible cellular beams were utilised in the floors to support light weight textile concrete, to save weight & to thread services through the holes of the cellular beams
Round tubular steel profiles were used as ‘tree’ columns in the courtyard, supporting lipped channel purlins to carry the relatively large span (for the element sizes used) over the courtyard in order to ‘feel’ like or simulate a ‘picnic’ area under ‘trees’ on a ‘lawn’ (It was an interesting exercise as the one will not stand without the other (‘trees’ & purlins) and the roof sheeting serves as cross bracing)
Rectangular & square tubes were utilised for the double glazed roof & wall structure facing the ski slope, as it was easier to pre-manufacture & test erect in a factory environment and could easily be bolted together on site in a relatively short period in adverse snowy conditions. The double glazing lets in sun & light during the day which heats the concrete floor which in turn emits the heat at night, gained during the day. The roof/wall glass & steel structure act a unit & is cross braced through the use of Structural silicon between the double glazing & steel frame
The combination (Hybrid) of materials & building methods utilised makes this project unique:
The Modul8 units (6 off) used for the project are a vast improvement on ‘traditional’ shipping containers. The original Backpackers’ shipping containers were reused, although flawed, as they are too narrow to accommodate & be practical for much more than small bedrooms or bathing ablutions. Also, if you cut holes in shipping containers you take away their inherent strength and need to reinforce the frame with more steel, which make it actually very uneconomical.
Modul8 pre-manufactured, modular units were design & manufactured off site (in a factory in Gauteng) to improve on all the inherent flaws of shipping containers but still utilise all the advantages of shipping containers. They insulated, wider, higher, longer, more flexible & lighter than shipping containers. They can be flat packed and transported in numbers on one truck if assembled on site. These were pre-assembled, together with the courtyard roof & glass roof/wall system in a factory in Gauteng, (without the shipping container units which were already utilised on site for some years), before being disassembled & transported to site for placement & completing the project.
A simple & cost effective IBR roof was screwed to lipped channel purlins (a very light structure was designed to be handled by manpower only), and the sods which used to cover the site & was placed to one side for re-use, was place on the roof sheets to help act as insulation (and greenery), together with insulation board, for the roof. Because the entire envelope is insulated, heat cannot escape easily. This was critical as sometimes temperatures of -20 C are reached in winter.
A 20’ shipping container was also utilised as a hot water storage tank. Polyuria was used to waterproof the inside of the container, and board insulation for thermal proofing, in order to use the container to store heat generated through arrays of vacuum tubes on the roof to heat water. The hot water is then used in the ablutions as well as to pump through the concrete floors to create a fly wheel effect of heat being released during the cold nights all year round, (and days during the winter).
Zink/Aluminium panels (Zincalume Structural Insulated Panels) were used to the Modul8 units around the covered interior courtyard for its aesthetic appearance, strength & longevity.
Green building rating/ environmental or sustainability considerations
Because the Modul8 units are manufactured off site, there is no damage to the site or the surroundings during the construction process, as no construction takes place on site accept for the foundations. The foundations are also of a lesser scale as the inherent strength of the Modul8 units and the shipping containers are already build into their structure, needed when transporting the units, thus the foundations do not have to be that strong.
As the building is pre-manufactured off site & then brought to site, the buildings can also be taken away again & the site can be totally rehabilitated.
As the Modul8 units are modular, materials were optimised to their modular size, resulting in very little to no cutting, resulting in no waste of materials, labour, equipment, tools or time.
All Modul8 units are ‘properly’ insulated, made in a controlled environment with strict quality control procedures and of high quality materials & finishes, resulting in less heating- & cooling costs, as well as less maintenance
Low maintenance to no maintenance materials were chosen to reduce maintenance costs in the long run, as well as reducing the materials, cleaning & maintaining agents which will go with maintaining a building
Because the Modul8 units are movable (transportable), they can be reused or up-scaled when they have reached the limit of their current use, e.g. if not required as a ski chalet at Afriski anymore, it can be moved to the coast as a beach cabana.
A Modul8 building can be ordered to be totally off-the-grid, as it can contain its own solar/wind/gas power generation and/or water heating mechanisms in order for it to be totally self-sustainable and/or in hard-to-reach and un-serviced locations.
Many years of design, various prototypes, extensive structural-, wind- & fire tests were done to get to the current design model:
Steel, in various forms e.g. Light Gauge Steel Frames, Hot rolled steel & cold rolled steel, galvanised bent plate, SIPs, etc. was chosen for its many positive attributes like strength-to-weight ratio, flexibility, cost-to-strength ration, durability, low maintenance, etc.
Many hours & details went into designing a structure which can be manufactured & assembled in a factory, can be lifted from the top, (instead of through the frame or with belts under the frame), is under 3 tons in weight in order for ‘standard’ truck cranes to lift the Modul8 units onto a truck & off again on site, flexible enough to withstand the current South African (and rest of Africa) road conditions on a truck, and last many decades on site to be even moved again at a later stage.
Modul8 is currently designed to be stacked 3 stories high, but with nominal steel sizes or wall thickness increases, this can be increased to many more stories.
Usually 1-3 days on sire are enough to place the Modul8 units, connect them to each other, waterproof them & connect the services to the units if necessary.
Weight was a major consideration when designing modular units, as well as the lifting method, as both have an influence on the transport of the units: It was thus critical to keep the weight low, while retaining the strength & flexibility of the units.
Strey Architects paid a lot of attention to designing for the maximum allowed size to fit on a truck without police escort, as well as to stick to standard sizes of materials.
The biggest challenge with Afriski is the inclement weather conditions, the altitude & the location of the site. Because of the altitude people inherently move & work slower. Because Afriski is located in a bowl, (less sun means more snow), the days are actually also shorter as the sun rises later over the East ridge & sets earlier over the West ridge. There are thus less daylight hours & the temperatures drop steeply when the sun disappears behind the Western ridge. Four seasons during the day is common, and it is known to snow in December & in April every year (there are weather records for the past 50 years). The distance of the site (Afriski) to the nearest town with most type of hardware & building supplies is at least a day (round trip) away, so one cannot ‘forget’ anything or construction will stand still.
Developing a pre-manufactured building system, which is built in a controlled factory environment have the following advantages, apart from the ones mentioned in Point 2-8:
- Workers return to their own accommodation each night so there is no need to house & feed the construction workers
- The weather does not influence the building process
- Better quality control can be adhered to
- Less to no waste and no waste needs to be removed from site
- Longer (normal) working days & working hours can be adhered to
The innovative use of several different types of steel products, and the combination thereof creating a hybrid & practical solution to the challenge, is noteworthy