| 91 T T Kelly Deeks Pushing boundaries reaps reward A recent project had LJT Joinery crafting the formwork for three, tapering concrete feature columns to frame the entrance to a new landmark winery building. JOINERY LJT Joinery With a proud history of nearly six decades supporting Canterbury’s construction sector with bespoke commercial, architectural, and residential joinery, LJT Joinery is now helping to improve construction efficiency with prefabrication and off-site construction. LJT was established in 1965 as an adjunct to renowned Timaru construction firm C. Lund & Son, which has since grown through five generations into one of New Zealand’s leading firms handling some of our largest commercial construction projects. For the past five years, LJT has been owned by company founder Charles Lund’s greatgreat-grandson, structural engineer Jamie Macgregor, whose experience in off-site construction sees LJT pushing the boundaries of traditional joinery, pairing craftsmanship with commercial workflows to deliver high-quality joinery work, on time and at scale. A recent project had LJT Joinery crafting the formwork for three, tapering concrete feature columns to frame the entrance to a new landmark winery building. A unique and challenging joinery item of significant size and scale, the largest column is 4m high, 3.5m wide at the base, tapering to less than 2m at the top. The required finish for the columns, their size, and their geometry meant they couldn’t be economically produced with in-situ concrete, so prefabricated glass reinforced concrete (GRC) shells were chosen. LJT worked closely with the GRC supplier and designers to develop a methodology for forming the two halves of each column, including ensuring the two halves could be stripped from their moulds with absolute accuracy at the seam where they joined. “From there, we broke the 3D surface down into component pieces, assembling the bulkheads, stringers, and lining,” Jamie says. “There were hundreds of tiny challenges along the way, like dealing with the fixing of the lining to avoid any blemishes in the concrete.” Each form was provided with a set of bulkheads, allowing them to be used in a staged approach, and for multiple castings and different column heights and terminations to be achieved. “It was a complex job,” Jamie says. “Concrete isn’t very flexible, so we needed a mould that would allow the column to be cast without leaving ugly lines down the surface. Then there is the structural stability of our formwork. Wet concrete is generally very heavy, so we design and built our formwork to withstand that weight.” Thankfully for this project – the decision to go with a GRC formwork reduced the pressure from the wet concrete significantly. The result has won LJT the 2024 Master Joiner Excellence Award for the Waitaki region. LJT has been making complex formwork for generations and has built up decades of expertise in what works, what is easy to strip, and what can be used for multiple pours. Jamie says there is no one solution, but LJT has invested years in building up a large collection of options for each unique project. “The key to well-executed concrete formwork is coordinating the geometry and thoroughly understanding how concrete construction works.” As LJT moves further down the prefabrication and off-site construction track, Jamie is proud of his family members, who have been behind the company’s success so far, and of his current team, whose expertise in timber combines with his in prefabrication to help deliver smooth results for the some of their most ambitious construction projects. ALSO SUPPLIERS OF A WIDE RANGE OF QUALITY WEATHERBOARDS, PROFILES AND MOULDINGS No. 1 Suppliers of : Posts • Poles • Piles • Farm Buildings Small Buildings • Dog Motels Concrete Troughs • Building Supplies Wooden Gates • Fencing Supplies 0800 4 posts (0800 476 787) www.greatsouthern.net.nz
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