Made to measure: Roofing at the cutting edge
[Pretoria, 8 March 2017]: LCP Roofing, leaders in roof truss technology, are renowned for their precision work, attention to detail and commitment to delivering world-class workmanship. Between a humble section of timber and an elegantly finished timber roof truss is a manufacturing process that has been fine-tuned and perfected over years.
From estimation and design to fabrication and quality control, LCP Roofing’s manufacturing process is one that is constantly improved upon and that looks to the future. William Long, LCP Roofing Designer, weighs in.
Estimation & design
After first contact with the client regarding the project, architectural drawings or designs including dimensions are requested by LCP Roofing from the client. “The designs and estimations done at LCP Roofing are solely based on the information supplied to us, which helps us to supply the client with an accurate and competitive quotation,” says Long. “That said, when it comes to manufacturing the roof, the dimensions are based on measurements that are taken on site, so as to ensure that possible errors that are made during the construction phase can be avoided. In addition, it is imperative that the client makes mention upfront of crucial information, such as loads being imposed on the roof structure, solar panels, air conditioning units, HVAC ducting, geysers and the like; failing to take this into account could have disastrous consequences,” he adds.
As a leader in its field, LCP Roofing prides itself in staying abreast of the latest design and estimation software. The company makes daily use of three software programmes, namely RoofCon, TrussCon and QuoteCon, designed and programmed by a conglomeration of structural engineers and industry professionals. The software is supplied by International Truss Systems, full system supplier to the prefabricated timber truss sector and an Illinois Tool Works (ITW)-owned company.
“RoofCon is used to create the basic design of each individual roof, excluding the design of the timber trusses, where after this basic design is imported into the second programme, TrussCon, which is used to design each individual truss,” explains Long. “This software also applies various loads to, and forces through, all members to test for any possible weakness. The design results then also assist in determining which timber sizes and timber grades are to be used. Once the designs have been optimised, the job file is exported to our third programme, QuoteCon, which drafts all quotations and delivery notes,” he adds.
Once the quotation has been accepted, manufacturing commences. Manufacturing of timber trusses consists of two main processes: cutting and assembly.
In the event that the roof is of a regular design with ceilings, timber from LCP Roofing’s stockpile is utilised and the manufacturing of the timber trusses is scheduled accordingly. Manufacturing a special roof, however, requires special material, which could include laminated timber, specialised decorative plates and any number of additional accessories. All timber used by LCP Roofing is sourced from highly reputable timber mills, who ensure that their supply is strictly from sustainable resources.
“By using TrussCon, we are now able to create a cutting bill for the saw operators in the factory. This cutting bill not only includes all required information on a printed copy, but also the digital Computer Numerically Controlled (CNC) cutting file for the autonomous SPIDA saws,” says Long, adding, “This has ensured that production capability has increased and quality control can be maintained.”
Accurate CNC measuring and cutting means that the timber in a roof truss exceeds the minimum requirements with regards to dimensional accuracy, while the computerised SPIDA saw automates angle and length setups. The job is simply downloaded via LAN or USB to the source computer and the angles and lengths are set to the precise measurements.
The traditional method of truss fabrication in South Africa, and by which more than 90% of plants operate, is by use of a framing table either on the floor or elevated for easier working, with nail plates placed and hammered by hand. Trusses are then flipped over and the operation is repeated. In a third operation, trusses are fed through a special finishing roller, which exerts up to 30 tons of force to fully embed the nail plates. This is a time-consuming operation and triple handling alongside inconsistent quality can offer up its problems.
In a bid to eliminate these manufacturing challenges, and after much research and two visits to suppliers in the United Kingdom, LCP Roofing purchased and imported a Hydraulic Birch Press which arrived and was installed in October 2011. In order to increase production and capacity, a second press was purchased and installed in February 2013.
“Using the printed copy of the cutting bill, the trusses are assembled with the correct timber sizes and grades as well as the correct nail plates. A ‘truss ticket’ is created, which gets stapled onto all the main trusses,” notes Long, who continues, “Not only does this ticket indicate truss numbers, it also indicates the design loads, approximate spacings, job numbers and all pertinent company information for future reference.”
LCP Roofing is a South African Technical Auditing Service (SATAS) Quality certified fabricator, is permitted to apply the mark to its product and is ISO 9001 accredited. All timber roof truss fabricators in South Africa should subscribe to and utilise the same quality controls, but in the absence of regular audits, both internal and external, a number of South African fabricators consistently ignore these controls, which are put into place to protect the consumer.
Of the 200+ timber roof truss fabricators in South Africa, only a handful have voluntarily registered with SATAS and operate under the South Africa National Standards (SANS) 1900 scheme (Quality Mark), and are subjected to regular SATAS or SABS inspections. Fewer than 100 of these fabricators are registered with the Institute for Timber Construction South Africa (ITC-SA).
“With a combined 32 years’ experience in design and manufacture, our estimators and designers are in constant search of more innovative, cost-effective methods of timber roof truss design,” comments Long, concluding, “This, coupled with management’s extensive experience in the fields of residential and commercial construction, means that LCP Roofing is best positioned to offer both the trade and consumer expert, custom advice in roof design.”
For more information, visit www.lcproofing.co.za.