AllyCAD Showcase

'A Namibian Alternative'


Rolf Trossbach,
Buhrmann & Partners
Windhoek

When you walk into the Habitat Research and Development Centre (HRDC), you find yourself stepping back in awe as you admire the structural masterpiece that greets you. The centre is built with virtually zero cost low-grade material found in rural areas, allowing local residents to be educated on the use of alternative building supplies for the construction of affordable homes.

"We were extremely privileged to have been appointed by project architect Nina Maritz, as the structural & civil engineer on the assignment," explains Rolf Trossbach, senior partner at Buhrmann & Partners, adding that the project was requested by the Ministry of Local Government and Housing in response to a design competition that was won in 2002.

"Our task as structural engineers was to assist with the design of the building using sustainable alternative materials. This meant that we had to retrain ourselves to think along unconventional lines since the project did not require us to conform to municipal regulations."

"The use of compressed soil-cement bricks was one of the most interesting materials that we used. These bricks were made on site using the Hydraform system; a patented machine rented from a local builder and stockpiled sand from Otjomuise a few kilometres away. The activity was quite labour intensive and required the bricks to be profiled, dry stacked and then plastered around window reveals and in corners," notes Rolf.

Another interesting building material was the use of rammed earth. "We used steel shutters to compress earth into a solid block, and then preserved the rammed earth by sealing it with seal oil. The sealant was relatively inexpensive and preserved the wall from further deterioration," explains Rolf.

Structures were pre-tested by constructing sample walls in order to test whether or not the various components were durable for building purposes. These structures were designed and detailed with the help of AllyCAD.

"I remember the first time that we were exposed to the program. We were given a three-month roads project and immediately realised that we needed the help of an extensive computer-aided draughting system in order to meet our deadline. This led us to acquire AllyCAD, which we used with great success. Since then we have used the product on all our projects as it cuts down on project time and helps us to produce a cost effective end result."
  Other innovative building materials include the use of the local invader prosopis tree for shade and security screens in front of windows and extensions of overhangs and walkway shading. "A local company cut timber 'droppers' or 'latte' from the invader trees in the valley north of the industrial area. The trees were then debarked and treated on site by being soaked in a mixture of old motor oil."

"The 'Spanish' reed found in local riverbeds was another invader plant that was used. The reeds were locally harvested by unskilled workers and were mainly used to provide ceiling walls and cladding for cupboard units. The ceilings were insulated by either using old feedbags filled with wool and lavender in order to prevent moth infestation, or by using waste polystyrene alternated with layers of flattened corrugated cardboard boxes," explains Rolf adding that the insulation had a minimum thickness of 60mm.

Rolf is quite proud as he explains the self-made gabion walls that the team created: "The large gabion retaining wall was constructed using wire baskets made on site and concrete bricks and rubble from a demolition site. The same demolition site also provided the B-grade steel that was used for steel windows, columns and roof structures on the building."

The use of old car tyres gave recycling a new meaning. "The tyres were used to build the archive walls and were stacked on top of each other and rammed full of a soil-cement mixture. Although our use of cement was restricted, we used small quantities as a binder in each tyre as the stockpile contained no clay. Tyre shops currently pay N$7 to dispose of tyres, providing residents with a useful recycling alternative," explains Rolf.

The first phase of the centre which consisted of the admin wing, was completed in April 2004, while the public wing was completed in September 2004. "I found this project particularly enjoyable as it challenged us to think out of the box and explore our creativity and imagination. After weeks of planning, testing and brainstorming, we are extremely pleased with the end result," Rolf says with contentment.


 
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