How the South African Timber Roof Truss
Industry has Evolved over 40 years

In order to better appreciate the major differences between traditional prefabricated timber roof trusses and the Turb-O-Truss™, and in particular the difference in the distribution chain, a brief history follows on how the industry has evolved and is presently operating.

Pre-punched metal connector plates were introduced to the South African market in the early 1960's, and soon there were several players on the local scene. There were however, only two major Truss System Providers competing for market share. The Truss System Providers are companies who supply the metal connector plates, truss pressing and sawing machinery; computer software and engineering back up).

Until then, the traditional roof truss market was that of on-site bolted trusses. During the following two decades these Truss System Providers were innovating by optimising engineering designs of both timber as well as their metal connector plates in order to gain an advantage on each other.

During the 1960’ and 70’s these Truss System Providers operated within their protection rights in terms of their patented metal connector plates. When these protection rights expired, their focus was already well established in the field of improvements to computer assisted software design programs as part of increasing their particular market share and retaining their customer base, being the licensed truss manufacturers.

The prime source of income for these Truss System Providers was (and still is) the sale of metal connector plates, which make up approximately 20 percent of the total material cost of a prefabricated timber roof truss. As such their profit motive was to sell connector plates to independent TRUSS FABRICATORS, who have been licensed to use the software programmes and connector plates supplied by a particular Truss System Provider.

They also offered engineering back up as well as the capital equipment in the form of truss pressing equipment, which insert the connector plates into the timber. They did not however, supply or in any way control the supply of timber to truss fabricators (which constitutes approximately 80% of the truss material cost). Independent truss fabricators were "licensed" by Truss System Providers, who then gave them the right, under license, to manufacture trusses using their connector plates and software engineering design program.

Truss fabricators sourced their timber requirements either direct from independent sawmills, or through timber agents. As such, sawmills had no say in the manufacturing process of a truss, and truss manufacturers had no reason to be loyal to any particular sawmill. His only obligation was to the Truss System Providers and to the customer, the building contractor.

As both the Truss System Providers as well as the truss fabricators wished to rapidly gain market share, the prefabricated truss industry positioned itself to cater for a wide market penetration which could vary from trusses for a single garage with a truss span of 3 metres to industrial trusses with 25 metre span, thereby competing both with traditional bolted timber trusses as well as with industrial steel trusses.

Needless to say, this strategy was lucrative for the Truss System Providers who had captive customers in the form of truss fabricators. The picture was less rosy for the truss fabricator who, in order to be able to compete with his competitors (other truss fabricators), had to ensure that he had the infrastructure to manufacture and deliver to site a very wide selection of trusses. This meant large premises, highly capital intensive articulated vehicles with 12m trailers, design and estimating staff, and large inventory of raw materials.

Yet roof truss plants sprang up like mushrooms, which soon led to an over capacity in the supply of prefabricated timber trusses. In the late 1980's the two major competitors joined forces, while other smaller systems have entered the market. Today, as design optimisation of both timber and connector plate has virtually reached its limit, Truss System Providers are marketing their connector plates by offering more sophisticated software design programmes in order to increase their market share by means of a larger fabricator base.

Although the primary focus of the Truss System Providers has been on the supply of connector plates for use in a factory environment with special pressing equipment, some attempt has been made by them to market a connector plate for on-site use. These connector plate designs are such, however, that they are not cost effective when compared to the commercially available (factory used) plates. Furthermore, Truss System Providers must be seen to be committed to their licensed truss fabricators, and therefore dare not undermine them by offering an on-site connector plate with complete design information direct to a builder, thus being seen to be competing with their own truss manufacturing customers.

When pre-fabricated timber roof trusses were introduced to the South African market in the 1960’s, Ralph became involved with the industry at grass roots level, and has developed together with the nail-plated truss industry over the past 40 years. During those early years, there were no computers or computer assisted design software available as is the case today. In fact, tangents and cosines were derived from Smoley’s Combined Tables, and only years later, from Scientific calculators.

Limiting span tables for standard double and mono pitch roof trusses had been developed by the Truss System Providers in HARD COPY, and there is absolutely no reason why this cannot still be the case for standard trusses for gable-to-gable standard low cost housing.

For the South African low-cost housing solution the key is to re-engineer down to basics, and thereby transfer more of the manufacturing activities to the building site where job creation is so desperately needed.

Information copied with the permission of Dr. Ralph Sörensen.

Dr. Ralph Sörensen is the original inventor and patent holder of the
rounded web solution for multiple pitch timber roof trusses. You can find more information about him and the Turb-O-Truss system on his web site .