By Kerryn Caulfield and Simon Heading, Technical Sales Consultant for Lavender The house that Rudi builtCE Pty Ltd.
Rudi Steinbusch is the owner of Lavender Composites; the Brisbane based firm suppling high-quality composite materials to advanced manufacturers and fabricators. His company has an enviable range of high quality products, composite processing and repair equipment, cutting tools to draw from. The separate engineering division that specialises in the analysis of composite structures and a complete composite tooling design service also came in handy.
Rudi’s journey to build his dream home commenced a number of years ago. The house was designed and built around an older partly-preserved house on the rise of a hill. The new house had to be integrated into what was left of the existing structure and designed to take full advantage of the view over the city of Brisbane.
The challenges the block presented were dwarfed by those Rudi encountered from architectural and building services as well as the council and certifiers, all of which had little knowledge of advanced materials and associated processes. He ultimately engaged himself to draw up the plans as one would an aerospace project.
The job dictated bespoke solutions. The walls were made from large-scale, prefabricated lightweight FRP structural panels, made from multiple-density foams forming thermal and acoustic barriers and produced in a one-shot epoxy vacuum infusion process. An exterior-grade epoxy was carefully sprayed onto the table prior to the lay-up of materials which eliminated the need for on-site painting and avoided delays due to bad weather. Metyx E-glass reinforcement and Fire Shield™ veil were laid either side of 50-100mm PET foam and extruded polystyrene foam. These blocks, some pre-cut and others profiled in-house with a hot wire and jig, were combined with pre-sealed EPP strips. Specially made threaded stainless lifting points were countersunk and inserted at vital load-carrying areas. These were rigorously tested at higher loads with an over-exaggerated safety factor due to the high winds and tight working space experienced on-site.
The panels were then finished off with a layer of release film and all vacuumed in position ready for the infusion. The epoxy resin chosen for this infusion was Sicomin SR8100 due to the mechanical properties and flow rate required, as the laminate in some places was up to 150mm thick. Even small gaps in the joining of the foam created vertical ‘hot spots’ as the resin peaked at exotherm, so it was critical to keep the foam’s accuracy throughout each panel. The resin performed extremely well and was cured sufficiently to provide a suitably stiff panel for release and transport off the mould table.
Each section was bonded to the steel skeleton with AEC Polymer’s Black Mamba, a modified polymer which offered excellent adhesion with enough elongation to handle any thermal expansion. Mechanical fixings were screwed into place to hold the panel in position while the adhesive cured. Once the walls on both the ground and upper levels were in place, the ‘regular’ trades could start their rough-in work, as they do with traditional builds. This was a key feature of this build, as it did not overwhelm the tradies who were unfamiliar with composite panels. The windows and doors slotted straight in with minimal adjustment, as they had been checked for square and tolerance when the panels were laid-up. Wiring and plumbing was easily accessible as the internal surface was still exposed right up to the last moment when regular plasterboard was put in place.
Rudi’s love and respect for advanced materials can be seen throughout the house in spectacular one-off composite features. The internal stairs are made from wafer-thin prepreg carbon fibre. An overhanging window box is made from carbon fibre and bonded in place with AEC Polymer’s SAF methacrylate adhesive. The kitchen benchtop is a precision CNC machined slab of titanium, featuring a subtle radius and hand-shaped bevel which he had sand-blasted to a luminous satin surface. Summer heat is managed by vertical sun-shade blades are made from prepreg spread carbon fibre tow.
One of the main features is the technically intricate and beautiful carbon columns that hold up one corner of the house.
Rudi acknowledges that the journey to build his dream home was a personal one and an outlet for his passion for advanced materials and precision engineering. Rudi says: “We know that composites offer less maintenance and repairs which in turn reduces life cycle costs. Lighter materials are less costly to transport and enable rapid installation. But for my wife and me, composites gave us greater design freedom, enabling the creation of beautifully complex shapes and finishes. In my view, this is the future of residential and multi-storey buildings.”
This article first appeared in: Connection Magazine – Issue 51: December, 2019