View Online

Fourways take off July 2019
Cape Construction take off 14 September 18
Interbuild take off 19 Aug 2018

Opinion – price over quality

Online since 5.11.2015 • Filed under Advertorial • From Issue 16 page(s) 156-157
Opinion – price over quality

The Institute for Timber Construction South Africa (ITC-SA) provides helpful advice and expresses the opinion that choosing price over quality with regards to workmanship and materials can lead to costly, disastrous and sometimes life-threatening situations.

The roof structure is arguably one of the most important construction elements of any residential building, protecting the occupier’s property, finishes and inhabitants from the elements. It is also one of the largest, heaviest and most costly structural components in any home design. Therefore, it is logical to expect that much planning, design and know-how would be invested to create an aesthetically pleasing, sound structure that will safely carry the induced loading, as well as offering acceptable longevity for the lifespan of the building. Although this may sound logical, many building owners unwisely choose price over quality with regards to workmanship and materials, which can lead to costly, disastrous and sometimes lifethreatening situations. The ITC-SA makes sourcing of reputable roof fabricators, erectors, inspectors and engineers easy – all the consumer needs to do is to contact the Institute directly or visit its website. The ITC-SA website provides a comprehensive list of all accredited members on a national basis.

Annual audits of fabricators

Every ITC-SA-accredited fabricator is audited annually regarding quality, competence and compliance to, inter alia, the South African National Standards – SANS 10243 – The Manufacture and Erection of Timber Roof Trusses. An annual Certificate of Competence is issued by the ITC-SA confirming that the fabricator complies with the National Design and Material Standards, and the ITC-SA requirements. Pre-fabricated roof trusses shall at all times be in accordance with the rational design requirements given by the engineer, as well as the SANS requirements below. To confirm compliance, an engineering certificate will be required on completion of any roof structure:

• SANS 10400-Part L

• SANS 10243

• SANS 10163

• SANS 1783-Part 1 and 2

• SANS 51075

• SANS 3575

• SANS 10096

Pre-fabricated roof trusses can only be approved when a rational design is available confirming that the material and truss design meet and/or exceed the SANS requirements.

Essential elements

The essential elements that need to be considered for ensuring a sound timber roof structure are:

1. The timber used must be structural timber and must comply with the material and, where applicable, treatment requirements to meet the design intent: Structural timber needs to be marked with red ink on the face of the timber at 1m intervals. If it does not bear these structural markings it will need to be condemned. Consumers should be aware of unmarked timber or timber with black crosses at the end as this marking confirms that the timber in question is not structural timber.

2. The designer must create an accurate cutting bill: The cutting bill will dictate the exact lengths and angles at which the timber must be cut for proper assembly.

3. The right engineering systems must be used: The ITC-SA provides accreditation for four systems that are recognised for meeting all South African prescribed design requirements.

• MiTek Industries SA

• International Truss Systems

• Multinail Africa

• Roof Truss Products

Note: The metal connector plates used must be supplied by the specific system that was applied in the design. In addition, the metal connector plates must be the right size, positioned correctly and located as per the standard methods and tolerances prescribed by the system.

4. All connections and bracing details must be in accordance with the rational design intent: In other words, everything that holds the structure together – such as the number of nails, bolts, washers, brackets and cleats – must be in accordance with the engineering design. All necessary bracing accessories must be stipulated on the design drawings.

Common pitfalls to take cognisance of and avoid

Pitfall 1: Choosing price over quality

The old adage, ‘you get what you pay for’, holds true when it comes to timber roof construction. Many consumers try to save on the roof construction and often end up spending more time remedying the consequences that arise from using sub-standard materials and workmanship. Bear in mind that to create a professional and sound  product, one needs to employ the know-how of professional, knowledgeable and experienced individuals. Initially, this will no doubt cost more than using non-qualified individuals but will, in the end, save money and avoid stress.

Pitfall 2: Choosing the right engineer

Use an ECSA registered professional, accredited with the ITC-SA, to design and certify the timber roof structure. Ensure that your chosen professional has a good working knowledge of timber and roof construction.

Pitfall 3: Prefabricated roof trusses are best

Prefabricated roof trusses are cut by advanced, specially-designed machinery and are therefore far more accurate than their hand-made counterparts. Prefabricated trusses, covered by a rational design, will also use less timber and will comply with all regulatory requirements, assuming they are designed by an ITC-SA accredited professional. In all industry related tests the ITC-SA has found site-made timber trusses to be more expensive than pre-manufactured timber roof trusses.

Pitfall 4: Guarantee

By using reputable fabricators, registered with the ITC-SA, one has peace of mind knowing that these companies or individuals are regularly audited and monitored. Should something go wrong, the consumer has recourse in the form of a manufacturing warranty. Part of the membership requirements for engineers accredited by the ITC-SA is that they all carry their own professional indemnity insurance cover for any professional negligence on their part with regards to the specific structures they sign-off and take responsibility for.

Conclusion

Internal investigation and findings by the ITC-SA confirms that 90% of hand/site made trusses do not comply with the relevant building regulation and SANS material and design specifications. Research also confirms that hand/site made timber roof trusses are, on average, 20% more expensive than premanufactured timber roof trusses. Pre-fabricated roof trusses come with guarantees in the form of a manufacturing warranty and an engineer’s certificate, which the owner may call upon should they need to have the roof structure repaired.

Institute for Timber Construction

South Africa (ITC-SA)

T +27 11 974 1061 / +27 11 392 6155

C +27 74 102 7175

E amanda@itc-sa.org / enquiries@itc-sa.org

W www.itc-sa.org

Issue 16

Issue 16

November 2015

This article was featured on page 156-157 of
To Build Magazine Issue 16.

Share this

Power Purchase  Conference 2018 take off 23 Nov 18
CAPE INDUSTRIAL FLOORING take off Feb19
 Affiliated Members AAAMSA - The Association of Architectural Aluminium Manufacturers of South Africa | Tel: 011 805 5002 CifA Institute for Landscape Architecture in South Africa KSA - Kitchen Specialist Association | Tel: 0827878806 SAIA