There's a lot of talk about sustainability and environmentally aware construction practices and hooray for that!
However, when people turn their nose up at our style of construction, telling us that timber is the only way to go for benefitting the environment and health of the homeowner, we have to disagree.
The majority of tradespeople coming out of their building apprenticeships have strong desires to work with timber. It's the romanticized ideal of strapping on the toolbelt, lining up some 2 x 4's, sliding their hands over the rough sawn beams, the smell of sawdust reminiscent of standing in Grandad's workshop when we were 8 years old and watching the dust flying around the room as he worked on his lathe shaping pieces of beauty, sawing and hammering away.
But how sustainable is timber?
A new report commissioned by the Australian Climate and Biodiversity Foundation (ACBF) looks into the forest and wood products industry. It looks at how we grow, harvest, mill, and use timber across the country, and what that means for housing, jobs, and climate goals.
Most of the timber used in house construction comes from softwood plantations, not native forests. But those plantations are under pressure—slow to grow, hard to expand, and vulnerable to fire and land-use competition.
Over 80% of the industry’s value comes from what happens after the tree hits the ground. That means:
- ~65% from manufacturing (turning timber into products like frames, cladding, panels, and paper), and
- ~15% from primary processing (like milling logs into sawn timber).
I wonder - wouldn't a true conservationist and nature lover rather have trees stay in the forests where they can sequester carbon and release oxygen so we can keep on breathing?!
Before construction, timber in homes is treated with various chemicals to protect it from decay, insects, and weathering. The treatments include numerous toxic chemicals, which would nullify any environmental considerations of timber framing.
For the purist, no amount of talk will change their thinking to alternative housing solutions. And that's ok. I too will always relish the smell of a freshly milled beam, there's nothing in the world like it!
But there's a growing number who also realise the need for alternative construction methods, and we are thankful at Havenwood for the research that has been undertaken to now have other ways of building that are more efficient, environmentally sound and sustainable.
The research has been done for us! And with over 170 homes across Australia using this method now over a number of years, we can vouch for its efficiency, durability and performance.
WHY WE USE SIPS (STRUCTURAL INSULATED PANELS) FOR OUR BUILDS.
Structural insulated panels (SIPs) are one of the most airtight and well insulated building systems available, making them an inherently green product. An airtight SIP building will use less energy to heat and cool, allow for better control over indoor environmental conditions and reduce construction waste.
Expanded Polystyrene is manufactured with a fire retardant raw material (EPS-FR). The EPS-FR will melt when in contact with a flame, shrinking away from the flame and will self-extinguish when removed from the source. EPS-FR is recommended for projects which require an efficient installation, cyclonic ratings, long spans and proven performance.
In a timber frame construction, wall heat conducts not just through insulation but more significantly through studs, reducing the overall efficiency of the system and gaps in the wall. Sill plates, top plates, electrical outlets, window jambs and even nail holes further reduce the true R-rating of the wall because of convective heat transfer.
A SIPs wall’s ability to perform closer to its rated R-value is a result of its tightness as a system, which minimises convective heat loss. The rigid EPS insulation of SIPs eliminates air circulation and moisture that is often prevalent in stud walls.
Strength and Durability
SIP Panels
SIP panels consist of a foam core sandwiched between two structural facings. This design provides exceptional strength and stability. SIP panels also have a superior load-bearing capacity compared to timber frames. They can withstand harsh weather conditions and are less susceptible to rot and decay.
Timber Frames
Timber frames are also strong and durable but do not provide the same level of support as SIP panels. They are more susceptible to warping due to moisture and can be damaged by insects and rodents.
Quick Assembly
Because SIP panels are prefabricated, they can be assembled quickly, reducing the time required for on-site construction. In fact, SIP panels can speed up construction time by up to 50% compared to traditional timber frames.
When it comes to the environment, SIP panels have a lower carbon footprint compared to traditional building materials. SIP panels are made from recyclable materials and are highly energy efficient, resulting in fewer emissions. Timber frames, while renewable, require more energy to manufacture and transport.
Benefits of SIPs Over Timber Frame
- Superior Energy Efficiency
- SIPs feature continuous insulation within the panels, eliminating gaps and reducing heat loss.
- Exceptional airtightness means lower energy bills and a more comfortable indoor environment.
- Timber frames, by contrast, can experience thermal bridging between studs, making them less efficient.
- Faster Construction Times
- SIPs are prefabricated and arrive ready to assemble, allowing for much faster on-site construction—often just a few days.
- Timber frame projects take longer, as the framework, insulation, and cladding are installed in multiple steps.
- Exceptional Strength and Durability
- SIPs provide a strong, rigid structure with excellent load-bearing capacity, distributing weight evenly for long-lasting performance.
- Timber frames rely heavily on the quality of the timber and joinery, and may warp or weaken over time.
- Low Maintenance
- SIPs are resistant to warping, rot, and pests, thanks to their closed-cell insulation and structural integrity.
- Timber frames require ongoing maintenance to prevent moisture damage, pest infestations, and decay.
- Improved Sustainability
- SIPs reduce construction waste due to their precision manufacturing and offer improved energy efficiency, lowering the carbon footprint of your building.
- While timber is a renewable resource, the potential for energy loss and higher maintenance demands can make timber frame construction less sustainable over time.
If you are a keen bean, and would like further reading, here's some resource materials below!
Source and further reading:
BON0126-Bondor-Tech-Data-Sheets-BondorPanel-v53.pdf
ACTC-8216-99-01R-I01R01-Bondor-Bushfire-Advisory-Note-06082024.pdf
https://ultrasips.com/blog/sip-panels-vs-timber-frame-comparison
SIPs vs timber frame - a side-by-side test | Smart SIPs
SIPs vs Timber Stud Framing: Sustainability Comparison in Australia | Maxa Design
Australia’s Timber Industry: Key Challenges Explained
SIPA_TB_02_Fire-Safety-with-SIP-Construction.pdf
Bondor Australia's Environmental Product Declaration
Bondor’s Commitment to Sustainability in Australia
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