By Gib Wettenhall, Secretary BRT March 2022
The ImLal drop slab hut provides a practical and attractive example of how we might deploy eucalypts, wattles and other native timbers to advance habitat creation, as well as show how we can offer resources to landowners and an income stream.
Construction techniques applied in building the hut within a central clearing were replicable, utilising a limited range of easily available and mostly inexpensive tools. The structure is both temporary and transportable, which held the added advantage of not requiring a council planning permit. From start to finish, bringing the project to fruition has not relied on energy-inefficient, external value chains.
Standing in a clearing within the 15ha ImLal biorich plantation, the drop slab hut acts as a focus for meetings, shelter and storage. A demonstration project, ImLal pursues the binary goals of optimising biodiversity, while producing useful resources from timber to seeds, through to foliage and locally rare endangered plants. By pursuing a binary approach of keeping and caring for country, we are choosing to act as custodians – just as the First Australians did for 65,000 years prior to settlement.
Twelve years ago, the biorich plantation replaced a bare degraded grazing paddock within the mining buffer zone for a kaolin quarry owned by SUVO Strategic Minerals. It now offers a model of biodiverse abundance, mimicking the structure of the swamp woodland that once would have stood there, showcasing some 40 local indigenous plant species in five layers from grasses and reeds to shrubs, understorey through to canopy trees. Surrounding the biodiverse core are 12 plots of farm forestry timber species.
In building the hut, Ballarat Region Treegrowers (BRT) and woodsman Lachlan Park followed three organising principles, which we describe as “going local, slow and carbon low.
We started with our focus on trees, the most renewable of material resources. We have sought to connect to our patch, seeking indigenous trees that possess a local provenance. They weren’t clearfelled en masse or sourced from exotic distant places. So, while many Australians may still prefer culturally to look elsewhere for, say, oak from Europe or teak from Asia, we pivoted to focus on sourcing locally. We sought timber for the hut from largely unsung common native trees, grown by local farm foresters.
Three of the five species we’re using were identified as eminently suitable in research done by BRT in the 1990s on which common native trees within our patch were most suited for timber construction. Most of these species have been trashed for low value uses in the past.
- So we have sugar gum that makes up the hut’s sturdy frame. Originally, sugar gum was not planted for its timber, but as shelter for sheep from killer frosts and bone-chilling winter winds. Planted extensively throughout the Western District’s shelter belts, it turns out to be a Class 1 naturally durable timber, perfect for exterior work. What a pity it’s almost exclusively felled for firewood. A BRT company set up by farm foresters, SMARTimbers, successfully sold sugar gum as decking and exterior cladding to architects for five years, although many of their clients were not prepared to pay a premium. Some of our members are still seeking to repurpose sugar gum as a substitute for the Asian rainforest timbers that we in the developed world blithely consume for exterior timber products, aiding and abetting tropical deforestation.
- Messmate stringybark sits comfortably in the drop slab walls. The Wombat Forest’s dominant eucalypt, it was extolled as “the most useful” of trees by gold digger and author William Howitt back in the gold rush era. It splits easily and was always a natural fit for the drop slab walling in miners’ huts. The drop slabs for the walls of miners’ and cattlemen’s huts were traditionally levered lengthways from a messmate or mountain ash log using a broad splitting axe. Lachie’s 21st century refinement is to replace pure brawn and deploy what is known as the Alaskan chainsaw mill technique. The Alaskan method calls for a chainsaw with long protruding metal rails added, so as it replicates in miniature a mobile sawmill. Such downscaling meant the Alaskan tree fellers could sled with huskies into back country, fall and disassemble a towering conifer on the spot.
- Black wattle once covered the plains, but was spurned as “rubbish” from the get-go, only fit for tanning. In reality, it burnishes beautifully to a fashionable wavy-red, ideal for floorboards. It’s very branchy and looks untidy, which was no doubt held against it. But from our experience, it just needs a regular prune. BRT farm forester Campbell Mercer milled black wattle boards without shrinkage or end checking (common to eucalypts) and sent samples to specialist timber retailer, Fairwood, in Melbourne for appraisal. They were amazed at its swirls of red colour and how it sustained such a good polish.
Increasingly, there’s a recognition that going local brings a comparative economic advantage. A place-based approach offers authenticity and a chain of custody back to the provenance of whatever you are producing.
Since the COVID pandemic and the fracture-lines opening up in globalisation, a world-wide search is on for alternative local product sources as disrupted supply chains in places like China drive up container costs and stretch delivery deadlines. Shortages in timber and building supplies provide a prime example of the breakdown in global supply chains. Innovative producers are now finding, like the wine industry did many years ago, that there’s added value in branding their products as being sourced from a local provenance. I look forward to the day when builders, architects and wood craftspeople proudly highlight how their fine cabinet timbers are sourced from a single block in the Central Highlands.
Making authentic local products demands in many ways a return to craftsmanship. The birth of the industrial era 200 years ago heralded the arrival of mass production and long distance external value chains. Both deadening to individual expression.
With wood, the old, slow ways involved felling a tree and working with it green on the spot to craft a boat, barn or Japanese temple of beauty. All done alone or in a small team with mostly inexpensive tools and without a battalion of expensive middle men. Pegging posts and beams together allowed for movement and shrinkage in the moist green wood.
I’ll never forget standing on a beach in Sulawesi with fellow farm foresters Digby Race and Rowan Reid seeing a line of seven graceful wooden boats with the classic curved prow of the Indonesian phinisi cargo boat. The product of a master builder, each boat was a different size, but made to the same template as used for over 1,000 years. While the workers wielded chain saws and wore thongs, not a nail gum was in sight. Pegs held each boat together. Today, business is booming. The phinisi boats from Bulukumba beach are regarded globally as the epitome of authenticity.
Like the artisans of old, our hut builder Lachie Park is a highly skilled and dedicated craftsman who chooses to work on his own with green wood. He prefers green wood as it’s much easier to cut, drill and chisel than inert and inflexible kiln dried hardwood. The downside is that it shrinks and splits more easily. Not a viable option for the ‘perfect’ finish, but fine for the rugged splendour of our drop slab hut.
Lachie came to us with the idea of updating the uniquely Aussie invention in hut building, the drop slab hut. While it may be part of our heritage, Lachie was not seeking to replicate the old miners and cattlemen’s huts of the high plains. Rather, he wanted to bring his full range of skills and modern technology to bear in reframing the drop slab hut technique, so that it was updated and fit for purpose for the 21st century. In peg making, for instance, Lachie pivoted to try out sugar gum, rather than seeking out the traditional English oak. It proved perfectly satisfactory.
Lachie sees no need to reinvent the drop slab wall itself. You’re making a whole wall from one piece of wood. As well as cladding, you’ve got a moisture barrier, weather seal, insulation, internal lining. Cut into short lengths, the messmate slabs are slotted into place between the standing posts of the hut’s frame. Literally, they are dropped into place from floor joist up; one on top of each other, with gravity replacing the job of glue or mortar in binding the wall together. The short horizontal lengths provide lateral strength without any fixing. The thick 2 inch walls ensure insulation.
In other echoes of our more place-based past, the wide eaves offer shelter and shade, as country homestead verandas once did. The granite foundation stones anchor the hut to the earth, while keeping termites at bay, as well as allowing for timber flooring and adequate airflow. Traditional board and batten barn-style doors are made strong and stable by holding them together with Z braces. Both the double rolling doors and the four pane casement window are made from black wattle. The recycled corrugated iron roof was rerolled by an early 20th century tank iron rolling machine. And the colonial British 'wattle and daub' weatherproofing tradition was adapted using the even older Indigenous ‘mud and stick’ approach. In our particular place, Lachie wove local silver wattle and coffee bush under the eaves, which was infilled with a mix of clay, grass and kangaroo dung.
Going carbon low
This follows as a consequence of the slow, place-based approach. When combined, these two constraints ensured a minimum of energy was expended in the hut’s construction.
Choosing unprocessed natural products, sourced locally – like the hut’s wood and the granite foundation stones – further reduces embedded energy. So does seeking out recycled products, like the corrugated iron roof.
In a paradoxical way, the granite foundation stones help the 21C drop slab hut sit lightly on the earth. Unlike concrete, no energy-sapping processing is involved, nor ravaging of the world’s river sand deltas. According to a 2013 estimate, there’s now two and half tonnes of concrete for every man, woman and child on Earth – a heavy carbon footprint, indeed.
Recent research published in the Cosmos science magazine pointed out that the year 2020 held another dubious distinction apart from the birth of the COVID pandemic. It marked the moment when the human-made, anthropogenic mass exceeded for the first time all of the living biomass of Earth’s plants, micro-organisms, people and animals. And processed construction materials like concrete and steel comprise the vast bulk of this human-made mass. Wood, I noted, is not on the list of anthropogenic objects. Trees are natural and renewable, clothing the Earth, offering gifts of habitat and succour to all Earth’s creatures.
Both temporary and transportable, our small and beautiful hut demonstrates how we might marry conservation and production, the only pathway we have to a truly sustainable future. We like to think that when taken together, the 21C drop slab hut and its surrounding biodiverse habitat offer a glimpse of how we might connect people to their place and to other than human species. The hut itself we see as a small practical example of how we might redirect our cultural values and use our hearts, heads and hands to live in a way more suited to the rhythms of the earth.
The project was auspiced by Forestry Australia.
It had funding support from Eucalypt Australia, SUVO Strategic Minerals, Lal Lal Wind Farm,
Moorabool Landcare Network, Lal Lal Catchment Group, the Responsible Wood program,
a GoFundMe campaign and HVP.