The Walltech Building System is comprised of an aluminium structural frame encapsulated within PIR foam protected by a barrier coating. While the structural frame resists the static and dynamic loads, surrounding foam provides lateral restrain to the aluminium studs, and enhanced stiffness to the wall. It also provides thermal insulation under normal and fire exposed conditions. The barrier coat protects the wall from fire, accidental damage, impact and weather including wind driven rain.
The weakest link of the structural frame of the Walltech system is the 'spring clip' which connects the top and bottom plates to the main stud. The performance of this clip was rigorously tested under static and dynamic conditions as per EBS TR 440 (Guidelines specified by the Department of the Housing & Construction for the testing and evaluation of products for cyclone-prone areas). All the clips tested satisfactorily sustained 10,201 load cycles (as required by the test specifications) illustrating that the 'spring clip' connector can be satisfactorily used in cyclonic wind regions. The characteristic tensile load capacity of each clip is rated as 9.5kN.
Walling frames have been properly designed in accordance with AS/NZS 1664.1:1997. In general, the frame consist of vertical studs (either 50mm x 50mm x 2mm or 100mm x 50mm x 2mm hollow sections) spaced at 500mm centres and engaged with top and bottom plates (top-hat sections) through 'spring clips'. Vertical studs are laterally restrained over their full height by the surrounding PIR foam. Walls can be 100mm, 150mm or 200mm depending on the applications. For in-plane shear resistance bracing panels have been designed, which can resist up to 10kN/m. External walls have been designed to resist ultimate design gust speed of 86m/sec. Full-scale walls will be tested at CSIRO for dynamic wind loads conditions to prove its suitability to perform in cyclonic wind regions in Australia.
Walltech walls are very light (under 100kg/m - depend on the wall thickness), and therefore loads transferred to the foundation is significantly less compared to the conventional walling systems. The vertical strength to weight ratio of Walltech walls is very high.
The rigid PIR foam has very good thermal stability. According to the available literature pentane-blown PIR agent contributes to excellent insulation performance of Walltech walls. Generally, 100mm thick wall could give an R value greater than 5, with 200mm thick walls offering even higher ratings.
A Full scale test will be done on a 2.4m x 2.4m wall to assess R rating of the composite wall as per ASTM C1363-97 at Branz in New Zealand with all its components assembled and with the external barrier coats applied.
The performance of typical foam insulated cladding panels will provide a relatively lower sound reduction and therefore lesser acoustic performance. Hence, Walltech intends to incorporate a sound barrier within its acoustically designed wall panels. One of the benefits of the unique manufacturing process of Walltech is its ability to incorporate a sound barrier within the wall in the production line. Walltech expects to achieve an Rw of 50 with the incorporation of its sound barrier. A performance assessment test will be done at CSIRO on a 3m wide full-scale wall for compliance with BCA.
Walltech has developed its own barrier coating which has significant fire resistance. Walltech initially expects to have 60/60/60 rating as per BCA for both load bearing and non-load bearing applications of its walls. Preliminary pilot fire test carried out at CSIRO has shown the barrier coat can withstand well over 1hour without any difficulty.
Many properties of this coating can be attributed to its structure and chemical constituents. It is hard, stable at high temperatures and, unlike many organic based materials, it is non-flammable. It is stable towards chemical attacks; it is especially acid-resistant and sulphate-resistant. It is strong and durable.
While the barrier coating provides sufficient protection against wind driven rain Walltech has developed its own sealing system of joints which can last the service life of the building. Walltech walls with water barriers will be rigorously tested at CSIRO under static water and dynamic wind driven rain. In-house testing carried out under severe conditions has shown excellent results.
Toxic mould and fungi growth are major problems faced by building owners. Mould and fungi forms when moisture is trapped and cannot dissipate. Organic coatings are one of the main causes of mould growth in all buildings, historical or newly built. The film itself allows moisture to form and run down to lower areas, such as cracks and crevasses, through gravity. Typical areas are the kitchen, bathroom and basements. High humidity and hot water from cooking and showering provides most of the heavy moisture that creates the perfect environment for the airborne mould spore to form and grow. If the moisture form between walls and the mould gets a foothold, it will eat anything upon which it exists creating toxic gases that build up in the wall cavities and are making many people ill. This mould will also eat the timber supports, producing rot and reducing the structural integrity of the building.
The Walltech barrier coating is made of inorganic materials. The use of an inorganic coating eliminates much of this problem as the coating breathes and does not trap moisture. The coating itself is inert and of a high alkali content which will not support mould growth.
The materials used in Walltech system in reasonably large quantities include:
The pentane based chemistry of PIR used by Walltech provides 100 percent reduction compared to other traditional blowing agents. Traditional blowing agents are considered to be ozone-depleting substances as over time cells break down in the presence of strong UV radiation and release chlorine or bromine atoms, which destroys ozone modules. The added benefit of very low global warming potential is an indirect advantage of pentane formulation. Significantly higher thermal resistance due to the very fine cell structure achieved in the PIR foam system also indirectly benefits global warming. In addition, the amount of volatile organic compounds generated in PIR formation is very low.
Most barrier coatings contain some content of cement. In general terms, during cement manufacturing one tonne of carbon dioxide is said to be released with every one tonne of cement manufactured. The barrier coating used in Walltech is made of inorganic materials and it does not release any ozone-depleting substances into the atmosphere during manufacturing. It does not have any volatile organic compounds.
Walltech uses boards manufactured using magnesium compounds for its bracing panels in contrast to commonly used plywood, fibre-cement sheets etc. Magnesium boards are claimed to be 100 percent green and not harmful to the atmosphere.