Neopor SIPs vs Polyurethane SIPs: What’s Better for Your Sustainable Home?

As sustainable building becomes a top priority for Australian homeowners, many are turning to Structural Insulated Panels (SIPs) as a smarter, more efficient way to build. But not all SIPs are created equal. Two common types of insulation used in SIPs are Graphite Neopor and Polyurethane (or Polyisocyanurate), and while both offer strong performance, there are some important differences to consider.

If you’re weighing up your options for a sustainable, energy-efficient home, this guide will help you understand the key advantages of Smart SIPs made with Graphite Neopor insulation over Polyurethane-based SIPs.

At a Glance: What’s the Difference?

Feature	Graphite Neopor SIPs	Polyurethane SIPs
Insulation Density	20 kg/m³	40–45 kg/m³
Weight (per 2.4m x 1.2m panel)	45.5–48.4 kg	~58 kg
R-value per kg	0.084–0.111	0.072
OSB Thickness	11mm	15mm
R-Value (140mm panel)	5.4	4.2
Environmental Impact	Lower	Higher
On-site Modifications	Easy	Not possible
Fire Safety	Does not release toxic gas	Releases hydrogen cyanide when burned

Smarter Insulation with Graphite Neopor

Neopor is an advanced form of expanded polystyrene (EPS), enhanced with graphite particles that reflect and absorb radiant heat. Compared to Polyurethane, Smart SIPs using Graphite Neopor offer a higher R-value-to-weight ratio, meaning you get excellent insulation without excessive material density or bulk.

While Polyurethane has a higher R-value per thickness, its performance can decline over time due to thermal drift. This is where the gas used during manufacturing is slowly replaced by air. Neopor, on the other hand, maintains its insulation performance over the life of the building.

Lightweight, Easier to Work With and Easier to Live With

Smart SIPs made with Neopor are more than 30% lighter than Polyurethane SIPs. That makes them:

• Easier and less expensive to transport

• Faster to install (lower labour and crane costs)

• Less physically demanding for builders and installers

• Less load-bearing on your foundations, flooring and roof structure

In contrast, Polyurethane SIPs are heavier, which increases the cost and complexity of:

• Transport and handling

• Foundation and framing requirements

• Crane time on site

• Labour and installation

Lightweight SIPs don’t just reduce your construction costs, they reduce the energy required to operate your home by reducing the thermal mass that needs to be heated or cooled.

On-Site Flexibility: A Clear Win for Neopor

One often-overlooked advantage of Graphite Neopor SIPs is their versatility during construction.

• Neopor makes it easy to adjust or cut panels on-site.

• If you need to run extra electrical or plumbing, Neopor can be modified using simple heated tools.

By contrast, Polyurethane SIPs cannot be modified on-site. They’re produced using high-pressure injection moulding, which requires individual moulds and results in longer production times. Once made, they can’t be easily adjusted.

Fire Safety Matters

When it comes to home safety, the difference between these materials becomes stark.

• Graphite Neopor is lightweight, safe to handle, and doesn’t produce toxic fumes when exposed to heat.

• Polyurethane (polyisocyanurate), when burnt, releases hydrogen cyanide (HCN) - a colourless but highly toxic gas with a faint almond smell. It’s the same compound found in smoke inhalation fatalities and is not something you want embedded in your walls or roof.

Sustainability: The Greener Choice

Sustainable construction isn’t just about energy savings during occupancy, it’s also about how much energy it takes to manufacture and transport materials.

• EPS and Neopor manufacturing uses less than 0.1% of the global oil supply, yet saves up to 200 times its energy use in thermal performance over time.

• Neopor is easier to recycle and uses less energy to produce than Polyurethane.

• Smart SIPs with Neopor create less waste during manufacturing and installation.

Simply put, Neopor SIPs have a lower carbon footprint across the entire building lifecycle.

Value for Money: What Are You Really Paying For?

Polyurethane SIPs cost more to manufacture and transport. They require thicker OSB skins due to pressure during the moulding process and contribute to higher build costs in nearly every area, from larger foundations to longer labour hours.

Smart SIPs made with Neopor insulation deliver:

• Lower material costs

• Faster build times

• Lower labour costs

• Long-term savings on energy

• Greater design flexibility

And they do it all while maintaining a smaller environmental footprint and delivering higher comfort levels year-round.

Neopor SIPs vs Polyurethane SIPs: The Verdict

When it comes to building a high-performance, sustainable home in Australia, Smart SIPs using Graphite Neopor are the clear winner.

They’re:

• More energy-efficient over time

• Safer to live in

• Faster to build with

• Lighter and easier to transport

• Better for the environment

• More cost-effective when considering the full building lifecycle

Ready to Build Smarter?

At Smart SIPs, we manufacture and supply Smart SIPs made with Graphite Neopor, delivering performance, safety and sustainability without compromise. Whether you're designing a high-efficiency home or an off-grid retreat, our SIPs are engineered for Australia’s climate and your peace of mind.

Get in touch today to talk to our team about how Smart SIPs can make your next build faster, safer and more efficient.