By Candace Sofianos King

The use of structural timber as an integral part of roof design and construction is garnering greater attention – we find out why.

Regarded by the timber industry as a sound and well performing resource in construction, the use of wood as a structural material adds various benefits to roof design. Its availability, sustainable traits, and workable nature turns timber into an efficient and attractive raw material of choice.

The award winning Cheré Botha School in the Western Cape makes use of a unique building design element in the form of exposed timber roof trusses. Credit: Elegant Roofing

Unlike steel and concrete, timber is a renewable resource in abundance in South Africa, says JD Botha of Biligom International – the innovative business behind the patented process of using moist eucalyptus to produce structural timber. He highlights that far more timber and roofing technologies have been adopted in the market in comparison to 10 years ago – a positive reality that will help reshape the roofing sector.

“The South African construction industry is still set on its old brick and mortar ways, but more timber frame housing is being built thanks to better workmanship, costs, timber preservatives and design technologies – so yes, timber is revolutionising the roofing and construction sector as a whole,” says Botha.

He notes that the timber roofing industry is quite competitive which lends itself to being sufficient where one can expect very competitive prices. “Roof truss designers must think out of the box when designing roofs to ensure their roofing quotes are more competitive. They should also make use of alternative technologies for this reason,” believes Botha.

Punting best practice

The local roofing industry is world class when it comes to industry standards, rational designs and inspections, says Botha. He adds that Biligom, like many structural timber manufacturers, is certified by the South African Technical Auditing Service (SATAS). “Like SABS, SATAS will conduct monthly audits to ensure quality is maintained via a stringent inspection and testing process,” explains Botha.

He adds, “Preservative treating is also inspected by the treatment manufacturers like Lonza to fortify correct and approved treating practices that adhere to the SANS codes. The NRCS will also do inspections to prevent illegal treatment plants from damaging the industry. System providers will supply truss plants with engineering software to ensure legal rational truss designs and provide the truss plants with metal connectors needed for a given designed roofing system. System providers will also have an inhouse engineer to check that certain class designs are correct to start manufacturing.”

Botha highlights that all erected roofs must be signed off by an accredited inspector or engineer who will approve the roof via an A19 Completion Certificate only if all building codes have been adhered to and if the roof has been erected correctly. The house owner requires this certification to obtain his or her occupancy certificate.

Not without its challenges

Despite its well-established industry standards and best practise, the roofing sector is not immune to its own specific challenges. Botha elaborates that only

In keeping ahead, roof truss designers are urged to think out of the box when designing roofs and should make use of alternative technologies. Credit: Biligom International

registered manufacturers and fabricators are being audited, resulting in the current illegal market boom.

“It’s impossible to enforce standards in rural areas as handmade and illegal roofs go up by the thousands and nothing is being done to prevent this. The politics in the roofing industry is at a breaking point because of different opinions from all role players. However, despite this, many stakeholders are trying to educate all industries, including ourselves,” Botha expresses.

He continues, “The roofing and construction industry has come from a very conservative background, and therefore it was very difficult for Biligom to include a new structural timber technology into the market. After a lot of sweat and educating architects, engineers, quantity surveyors and governmental institutions, it must be said that we are now picking the fruits.”

Trends to look out for

Botha notes that while hurdles remain, the timber roof industry is seeing several enlightening trends take shape. He notes that larger 900mm c/c truss spacings on concrete tile roofs is a major trend in certain locations in the country by making use of 38 x 38 battens. This is a huge cost saver on any roof, which is increasingly being used on low and medium cost housing projects.

“With the first Cross Laminated Timber (CLT) structures already built in the Western Cape, we foresee that CLT projects will become a standardised trend in architectural designs for large building projects in the future as it has already proved itself as a steel and concrete replacement in high-rise buildings in the EU, US and Canada. Testing of a stronger Biligom CLT is in the process,” notes Botha.

Botha believes that due to South Africa’s crumbling economy, we will start seeing smarter, greener and more cost-effective roof designs. “More eco-friendly projects – both private and governmental – are planned for the future, therefore sustainable roofing products will need to be used as architects will receive green credits if specified. It’s tough out there for truss plants if buildings are not being constructed and therefore the smarter, educated and open-minded truss plant owners will reap the rewards.”