A supposedly ‘rubbish’ timber, Lachie has instead found that black wattle delivers superior quality floor boards. It’s far harder and denser than Baltic pine, which was brought over as ballast from Scandinavia in the gold rush era and was laid as flooring in Ballarat throughout the 19th century. It’s even harder and denser than mountain ash (Eucalyptus regnans), which until the 1970s formed three-quarters of the new house frames and flooring in Victoria.
Laying the black wattle floor boards in the 21C drop slab hut has gone smoothly. The stability of acacia compared with a eucalypt avoids tension and shrinkage problems. When Lucas sawmilled as green wood at 24mm, the black wattle was perfectly well-behaved, shaving down to a standard 19mm thick by 112mm wide board.
Lachie chose to use a classic shiplap profile, where the rebate on opposite sides of the panel interlocks the boards as securely as tongue and groove. The boards were lain athwart chainsaw-milled messmate joists, 500mm thick by 150mm wide, which were set 450mm apart and notched into the bottom plate beam. Through-nailing was preferred by Lachie, as unlike trendy secret nailing, it allows the boards to be recycled. Secret nailing offers another example of Western culture’s myopic vision triumphing over what’s best for the planet.
The wavy-red floor boards are yet to be sanded and oiled – the next step! In the meantime, Lachie has nailed a recycled corrugated iron roof above as protection from the weather. It was rerolled by an early 20th century tank iron rolling machine that was originally designed to put the curves into straight iron. Now deployed to bring back old distorted corrugated iron, the machine only works where the iron is malleable. Modern iron may look on the surface flashy, but it’s high tensile and – surprise, surprise – not recyclable.
As well as being attached to the three pairs of pegged sugar gum rafters, the roof is supported horizontally by round bush poles. Skinny as they are, the bush poles serve as sturdy purlins that are fixed to the rafters with batten screws and twitched with tie wire at each end.
Also sourced from sugar gum, the 100mm diameter bush poles are 12 year old thinnings hailing from the sugar gum plantation of Ballarat Region Treegrower (BRT) farm forester, Phil Kinghorn. Farm foresters are constantly attempting to dream up ways of making money from plantation thinnings. As a plantation grows, every second tree needs removing on a regular basis if the best formed and straightest tree trunks are to thicken up sufficiently for most timber uses. Skinny bush poles playing a support role in construction are one way to fill this gap.
Minimally processed, the poles were chainsawed flat on top and bottom sides, otherwise retaining the outlines of their origins. “It makes for a pleasing organic contrast, I think,” said Lachie.
When it comes to natural products, less can often mean more.
For all eight Steps, visit – https://www.biorichplantations.com/blog/category/21c-drop-slab-hut