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What happens when you put hemp into a structural brick?

Will Stewart, director and co-owner of Natural Brick, joins us to unpack how his team is rethinking one of the most familiar building products around, from what goes into the mix to how it performs once it hits the wall.

Natural Brick’s current brick uses hemp grown in NSW, making up around 45–50% of the mix by volume. Rather than being kiln-fired, the bricks are naturally cured using solar heat over an eight-week process. The result is a load-bearing single-skin brick that has achieved an unconfined compressive strength of more than 11 MPa, with recent testing closer to 15 MPa, and an impressive 180/180/180 fire resistance result.

Will gets into the practical details builders and architects actually want to know: how the brick handles moisture, salt attack and weathering, why it needs to be laid dry, what the long curing time means for project planning, and where the current carbon assessments fall short.

We also get into the more experimental side of Natural Brick, from algae-based bricks and bricks made from construction waste to furniture made from recycled stone and even a bone terrazzo table.

And then there’s the custom work. Natural Brick has developed an in-house mould-making process that can bring a custom curved brick mould down from a typical five-figure setup to around $1,200, while allowing moulds to be reused across projects.

It’s a conversation about what happens when you take a conventional building product, question how it’s made, and start looking at waste, materials, manufacturing and performance differently.

EPISODE HIGHLIGHTS

• How Natural Brick makes a structural brick using around 45–50% hemp by volume
• Why Natural Brick uses solar curing instead of kiln firing or mechanical curing
• The testing behind the product, including 11+ MPa compressive strength and a 180/180/180 fire resistance result
• What builders need to know about moisture, durability, weathering and laying the bricks
• How custom curved brick moulds can be made for around $1,200 rather than a typical five-figure setup
• The reality of measuring embodied carbon, including the limitations of current assessment processes
• What Natural Brick is experimenting with next, including algae and construction-waste bricks
• Inside the furniture studio, where recycled stone, industrial by-products and even animal bone become new materials

CHAPTERS

0:00 - Meet Will Stewart and how Natural Brick began
1:58 - Building schools in Kenya, and what it taught him
6:10 - Back to bricks: why mud bricks didn't work
7:36 - The Lutyens brick and its long format
9:50 - How the brick is actually made
12:14 - Switching to hemp, and why it works better
13:49 - Solar curing instead of a kiln
14:29 - Inside the mix: hemp, sand, cement, fly ash, pigment
17:27 - The carbon numbers and the Think Brick study
20:10 - Where carbon assessment falls short
21:32 - Compressive strength and the 180/180/180 fire result
23:01 - Vapour permeability, moisture and laying dry
24:54 - Thermal performance and R-value
27:06 - R&D: the algae brick and construction-waste bricks
36:59 - A curved apartment project, and reusing moulds
42:19 - Weathering, sealing and cleaning without acid
46:38 - What's next, and the furniture side
54:39 - The biggest constraint, and getting to low carbon
56:05 - Quickfire

ABOUT THE GUEST

Will Stewart is director and co-owner of Natural Brick, a New South Wales maker of handmade, hemp-based masonry. He came to bricks after around six years building schools in Kenya and Uganda, then a stint in beverage sales, and now runs the business with two co-owners out of a solar-powered factory in Warragamba, at the foot of the Blue Mountains.

LEARN MORE
Natural Brick: https://naturalbrick.com.au
Sustainable Builders Alliance (SBA): https://www.thesba.com.au

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Most climate conversations in sport start with the elite game. Tom Campbell starts with the clubrooms: a grassroots footy club whose power bill dropped from $9,000 a year to $900, with the $8,000 difference going straight back into the club.

Brian and Simon are joined by Tom Campbell, co-founder of Footy for Climate, which he started while playing at North Melbourne, in the season the Black Summer bushfires filled the training track with smoke. Its Power Forward program puts solar and battery systems onto community footy clubs so the savings stay in the community game.

Most of the hour lands on the part builders will recognise: the clubrooms are owned by councils, the tenants pay the bills, and almost nobody is funded to fix them. Campbell is blunt that climate action has to save money before a club or council will touch it, which is the same case builders make for efficiency, insulation and retrofit every day. The conversation also gets into what the savings unlock, from concussion screening at community level to why a changing climate is already moving the fixture.

EPISODE HIGHLIGHTS

• Power Forward, and what solar plus battery does to a community club's power bill
• Why councils own the clubrooms, and why that is the hardest part to solve
• Why solar on its own no longer stacks up, and what winter footy does to the numbers
• What the savings unlock, including concussion screening at community level
• The $20 million that would retrofit 220 Victorian clubs and save $3.5 million a year

CHAPTERS

0:00 - Meet Tom Campbell, and why Black Summer started Footy for Climate
4:07 - Offsetting player flights, and why that model stopped
7:10 - Power Forward, and a club power bill from $9,000 to $900
11:24 - The council owns the clubrooms, so how does a club get solar?
15:16 - Why solar alone no longer stacks up without a battery
18:48 - What the savings unlock, beyond the carbon
24:34 - Is the AFL on board, and does it fund the work?
26:49 - Mandatory reporting, and the clubs already moving
31:16 - Having a climate conversation inside a footy club
35:32 - An open chequebook, and the $20 million Victoria needs
39:17 - Concussion, and neuropsych screening at community level
41:22 - Five years out, and 500 clubs by 2030
43:25 - What players know, and the media training behind it
47:42 - Climate is already moving the fixture
50:15 - What keeps you going when progress is slow
53:05 - Quickfire

ABOUT TOM CAMPBELL

Tom Campbell is co-founder of Footy for Climate, which he started over five years ago while playing at the North Melbourne Football Club. He played 14 years of AFL across Melbourne, St Kilda, North Melbourne and the Western Bulldogs before retiring in 2026. Footy for Climate began by offsetting player flights and now runs Power Forward, a program putting solar and battery systems onto grassroots footy clubs so the savings can go back into the community game.

LEARN MORE
Footy for Climate: https://footyforclimate.org.au
Sustainable Builders Alliance (SBA): https://www.thesba.com.au

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Australia is the seventh most forested country on earth, yet it imports around $5 billion more timber than it sells, and the gap grows every year. Matt de Jongh, a forester of about 25 years and now with Responsible Wood, the body behind timber certification in Australia and New Zealand, explains how that happened. His blunt version: at home, we have run out of wood.

Most of the conversation digs into what "sustainably managed" actually means on the ground. Matt breaks down the difference between certified and uncertified timber, how the "no deforestation" rule works when trees are still being cut, and why independent third-party auditing, not a landholder's word, is what sits behind a Responsible Wood or PEFC label.

From there it turns political. Matt argues that ending native forest logging in Victoria and WA has pushed demand onto Tasmania and onto imports from countries with weaker rules, and he uses the Pilliga koala population as his example of what happens after active management stops. The episode also covers mass timber, the carbon locked inside a timber product, and why architects keep coming back to wood.

EPISODE HIGHLIGHTS

• Why the seventh most forested country still imports about $5 billion more timber than it exports
• What "no deforestation" actually means: permanent land-use change, not selective harvest and regrowth
• Certified vs uncertified timber, and how independent auditing backs a Responsible Wood or PEFC label
• The Pilliga koala argument, and what Matt says happened after a managed forest became a national park
• Mass timber, stored carbon and the case for building in wood

CHAPTERS

0:00 - Meet Matt de Jongh, and the science of forestry
4:33 - What "sustainably managed" actually means
5:17 - Plantations, native forests and how thinning works
7:33 - "No deforestation" defined, and who checks it
13:22 - Forest certification, PEFC and Responsible Wood
18:25 - Certified vs uncertified timber, and the illegal logging laws
24:08 - Why timber is the ultimate renewable, and biogenic carbon
26:55 - The forests that aren't certified, and small landholders
30:25 - WA's gum plantations and the scheme that planted in the wrong place
35:05 - The $5 billion question: a forested country that still imports timber
39:12 - A shrinking forest estate and the housing crisis
43:24 - Engineered timber, mass timber and traceability
46:17 - Is there a fix, and why it is political
49:09 - Victoria, Tasmania and the media story
51:19 - The Pilliga, koalas and what happens when management stops
1:05:47 - The silver bullet: procurement and wood encouragement policies
1:11:15 - Quickfire

ABOUT THE GUEST

Matt de Jongh is a forester with around 25 years in the industry, from operational forestry across New South Wales to policy roles with the Australian government, and he is a director of Forestry Australia. He now works with Responsible Wood, the standards body that runs forest and chain-of-custody certification in Australia and New Zealand and represents PEFC locally.

LEARN MORE
Responsible Wood: https://www.responsiblewood.org.au
Sustainable Builders Alliance (SBA): https://www.thesba.com.au

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Australia's National Construction Code climate zones and NatHERS and PHPP models built on them, are calculated from climate averages that are no longer holding. When Brian raises this, Monash University climate scientist Ailie Gallant stops and admits it's a gap: she hadn't considered the building code angle, and says she'll take it back to her team to look into.

The bulk of the episode is a plain-language climate science primer, delivered without jargon by someone who does this for a living. Ailie explains the greenhouse effect as a window that different gases open and close, walks through carbon dioxide moving from 280 to 432 parts per million, and puts that in context: roughly a 55% increase in eighty to a hundred years, where comparable past shifts took millions. She also explains why the scientific consensus holds despite researchers actively trying to discredit each other's work.

For builders and designers, the practical content is in what comes next. Ailie sets out the regional picture: drier winters and more time in drought across southern Australia, hotter and more humid up north, fewer cyclones but more intense ones, and rainfall arriving in short violent bursts rather than steadily, which is a drainage problem before it's anything else. She's also cautiously optimistic: the worst emissions scenarios modelled a decade ago now look unrealistic, and the conversation lands on two to three degrees rather than five or six.

EPISODE HIGHLIGHTS

• Whether NCC climate zones will shift and why a 100 year house in Melbourne might need to be built for central New South Wales
• "This is not our new normal, this is our changing normal" why updating the code once won't be enough
• Carbon dioxide from 280 to 432 parts per million: a 55% jump in a century, where past shifts took millions of years
• Hotter and drier down south, hotter and more humid up north, and cyclones that come less often but hit harder
• Rain arriving in short violent bursts instead of steadily: a drainage problem waiting to happen

LEARN MORE
Monash University: Ailie Gallant: https://www.linkedin.com/in/ailie-gallant-b36839a9/
ARC Centre of Excellence for Weather of the 21st Century: https://www.21centuryweather.org.au/
Sustainable Builders Alliance (SBA): https://www.thesba.com.au

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Andy Marlow's definition of efficiency in passive house and airtightness will annoy some people: it's doing the bare minimum required to clear the hurdle, which he says is much the same as being really bloody lazy. Andy is a director at Envirotecture, a long-time passive house advocate and former Australian Passive House Association board member — and he thinks the industry's obsession with beating its own numbers is costing builders money for no measurable gain.

The core of the conversation is where the point of diminishing returns actually sits for high performance. Once a building is genuinely airtight, the model becomes predictable (you can't model a sieve) and that predictability is what lets you cut back everything else. Andy walks through the UK apartment work presented at the Passive House Conference where parts of the building are deliberately built worse than code because the form factor absorbs it, the concrete footings nobody needs to perfect, and the one thing you can never compromise on: condensation risk.

Brian makes the same case from the other direction — that a decade of chasing certified air-tightness is what teaches you how much performance you can buy for far less. They get into the airtightness arms race between builders, the bloke who hit 0.06 and probably wasted his weekends doing it, achieving 2 ACH cheaply through the plasterboard line, and whether a tiered certification pathway would drag the volume market across the line. Andy also explains the relaunch of Passive House Design & Construct as pre-designed-only homes — the same logic applied to design fees.

EPISODE HIGHLIGHTS

• An educated way to cut corners.
• The airtightness arms race — 0.6 versus 0.5 versus the 0.06 warehouse, and where the ego takes over from the engineering
• Condensation risk as the one thing you don't get to compromise, and Andy's caution on loosening airtightness
• Low Energy Building as the sensible tier down, and why a 300mm-plus wall isn't always financially sane
• Health, comfort and longevity as the real product — "no one cares about energy efficiency"
• Applying the same logic to design: the relaunch of Passive House Design & Construct as pre-designed homes you can't modify

LEARN MORE
Envirotecture: https://www.envirotecture.com.au/
Passive House Design & Construct: https://passivhausdc.com.au/
Sustainable Builders Alliance (SBA): https://www.thesba.com.au

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Kyle Zanetto lost close to $400,000 in a single year working eighty-hour weeks. Luke Davies sat $75,000 in overdraft with a maxed-out mortgage and had to sell his house. Both now run successful Tasmanian building companies — and together founded Future Builder to stop other builders repeating their mistakes.

The core of the conversation is what sits between a good builder and a profitable building business: markup versus margin, estimating bottlenecks, recovering overheads, and how business structure determines the numbers. As Luke puts it, if someone tells you what your markup should be, they don't know your business.

Kyle explains how a 30-point client questionnaire now filters roughly fifty leads down to two, and why that shift — not cost-cutting — is what protects quality.

They also walk through Future Builder itself: the asset library, the courses, the Monday masterminds, and Alfie, the AI business companion Luke has been building for nine months that runs a 104-point health check across six business pillars and connects to Xero. 

The conversation moves into lean methodology on site, burnout and why builders won't ask for help, suicide in the industry, and what each of them would change in the NCC if given one shot.

EPISODE HIGHLIGHTS

• How a builders markup can make or break a business — and the difference between markup and net profit
• Kyle's 30-point client entry questionnaire: open-book negotiated tenders, 30% cash, and turning down 48 of 50 leads
• Luke's approach to saying yes to the right job even when the schedule is full
• Alfie, the AI business companion: business life stages from start-up to prime, the 104-point health check
• Lean methodology on the building site — spaghetti maps, rework, and the triple hit to the bottom line
• Burnout, self-awareness and hustle culture: the routines to business owners use to keep operating at high load

LEARN MORE
Future Builder: https://www.futurebuilder.co/
Zanetto Builders: https://www.zanettobuilders.com.au/
Davies Construction: https://www.daviesconstruction.com.au/
Sustainable Builders Alliance (SBA): https://www.thesba.com.au

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Sustainable Builders Alliance (SBA): https://www.thesba.com.au

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Most builders are more exposed than they realise, and usually find out at the worst possible moment. 

In this episode, Daniel Webber of Webber Insurance, a broker who specialises in complex construction risk, walks through the cover a builder actually needs and what each policy really does.

The core of the conversation is the essentials — home warranty, contract works material damage, and public liability — then the covers builders routinely underestimate: statutory liability, professional indemnity, cyber, and key-person. Daniel is direct about where the gaps sit and why assuming you're covered is an expensive habit.
It also digs into the traps: worker-to-worker claims where an injured sub's insurer comes after the builder, insuring the existing structure on renovations, and how blown-out project values or timelines can quietly void a claim. The throughline is simple — more insurance isn't always the answer, but understanding your cover, running an annual health check, and getting your subcontractor contracts right are non-negotiable.

EPISODE HIGHLIGHTS

• The three core policies every residential builder needs — and what each actually covers
• Why home warranty protects the homeowner, not the builder, and how your limit is tied to your finances
• Worker-to-worker claims: how an injured subcontractor's insurer comes after the builder
• Statutory liability, and why public liability won't cover SafeWork fines or investigations
• Professional indemnity for builders — and the "design and construct" element people miss
• Insuring the existing structure on renovations, and the home-insurance chat to have with clients
• Why fixing your subcontractor contracts is the single biggest risk lever a builder has

LEARN MORE
Webber Insurance: https://www.webberinsurance.com.au
Sustainable Builders Alliance (SBA): https://www.thesba.com.au

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The Sustainable Builders Alliance

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In this episode, Ben Bardon, CEO of the National Australian Apprenticeships Association (NAAA), shares his journey from working as a painter and decorator to becoming one of Australia's leading voices on apprenticeships, skills development, and workforce planning. The conversation explores the challenges facing the construction industry, including labour shortages, apprenticeship completion rates, skills pathways, and the growing demand for qualified tradespeople needed to meet Australia's housing and infrastructure targets. 

The discussion dives into the realities of the apprenticeship system, examining how young people enter the trades, the role of schools and vocational education, and the barriers preventing more Australians from pursuing construction careers. Ben also unpacks the impact of migration, government incentives, workforce participation, and industry culture, while highlighting practical solutions to improve apprenticeship outcomes, attract more women into the trades, and build a stronger, more sustainable construction workforce for the future.

EPISODE HIGHLIGHTS

•  Ben's journey from tradesperson and educator to CEO of the National Australian Apprenticeships Association 
•  The state of apprenticeships and workforce shortages in the Australian construction industry 
•  Why apprenticeship commencements and completions are struggling to keep pace with demand 
•  School pathways, vocational education, and helping young people discover careers in the trades 
•  The role of migration, government incentives, and workforce planning in addressing skills shortages 
•  Supporting apprentices through training, mentoring, and industry pathways 
•  Increasing female participation and creating more inclusive construction workplaces 
•  The future of Australia's construction workforce and the challenge of delivering enough skilled tradespeople

LEARN MORE

NAAA: https://www.naaa.com.au/about-us
Sustainable Builders Alliance (SBA): https://www.thesba.com.au

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The Sustainable Builders Alliance

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In this episode, Candice Halliday from CNA Design Studio shares her journey from founding a successful architecture practice to becoming a leading voice for emerging professionals within the Australian architecture industry. As the incoming president of Imagine at the Australian Institute of Architects, Candice discusses the importance of collaboration, sustainable design, and creating healthier, higher-performing buildings that meet the challenges of a changing climate. 

The conversation explores the role of Passive House principles, building performance, retrofit design, and the future of sustainable construction in Australia. Candice shares insights from the Thrive Passive House Conference, discusses the need for better building quality and public education, and explains why architects, builders, policymakers, and industry organisations must work together to drive meaningful change. We also dive into adaptive reuse, reducing embodied carbon, improving building standards, and how emerging technologies and AI could help shape the future of architecture and construction.

EPISODE HIGHLIGHTS

•  Candice's journey from sole practitioner to founder of a growing architecture practice 
•  Lessons and insights from the Thrive Passive House Conference 
•  Passive House principles and improving building performance in Australia 
•  Building healthier, more energy-efficient homes through better design 
•  Retrofit strategies, adaptive reuse, and reducing embodied carbon 
•  The future of sustainable architecture and the role of the NCC 
•  Why collaboration between architects, builders, and industry bodies matters 
•  AI, innovation, and emerging opportunities for the next generation of architects

LEARN MORE

CNA Design Studio: https://www.cnadesignstudio.com/
Sustainable Builders Alliance (SBA): https://www.thesba.com.au

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The Sustainable Builders Alliance

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In this episode, Ben Walsham from Arkata shares his journey from studying as an architect to becoming a certified energy assessor, and how witnessing underperforming, single-glazed luxury developments drove him to step away from traditional volume building to tackle Australia's home performance crisis. The conversation explores how a simple shift in mindset, moving away from added R-values and looking at total U-values instead, can completely reframe how architects and homeowners understand heat loss and window budgets.

The conversation digs deep into the realities of modern construction, bridging the gap between design theory and actual on-site sequencing. Ben explains how Arkata utilises early-stage thermal modelling and a unique "value engineering for performance" dashboard to eliminate weeks of frustrating coordination, helping clients optimise their designs before town planning approval. We also dive into the future of the industry, unpacking the upcoming 2029 code changes, the rise of AI-powered compliance tools like NatHERS Hero, and why mandatory energy disclosure at the point of sale is the ultimate financial catalyst needed to transform Australia’s housing market.

EPISODE HIGHLIGHTS

• Ben’s origin story: from volume builder graduate architect to sustainability consultant 
• The reality gap: how architecture curriculum falls short on contract admin and buildability 
• Reframing metrics: why added R-values mislead the industry and how U-values expose glass as the weakest link 
• Value engineering for performance: using upfront dashboards to balance budgets and hit 8+ star ratings 
• The 2029 code roadmap: AI-powered software, NatHERS Hero, and scaling efficiency to 200,000 homes a year 
• As-built verification: the transition toward airtightness testing and closing the performance gap 
• Mandatory energy disclosure: how banks, ESG ratings, and point-of-sale reporting will drive the retrofit economy 
• Quick-fire round: passive house vs. solar design, SIPS alternative construction, and a surprising love for death metal

LEARN MORE

• Arkata: https://arkata.com/  
• Sustainable Builders Alliance (SBA): https://www.thesba.com.au

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• The Sustainable Builders Yak Podcast