Why Are New Homes in Australia Growing Mould? And What Can Be Done About It?

High-performance home with ventilated roof cavity to prevent mould

There’s growing awareness in Australia around mould—and for good reason. Once brushed off as just a cosmetic issue, mould is now recognised as a serious threat to health, comfort, and the longevity of your home.

What’s even more concerning? Mould isn’t just found in old, poorly maintained properties. It’s showing up in brand-new homes across the country—including right here in the South West.

So, what’s going wrong? And more importantly, what can you do about it?

The Hidden Damp Crisis in Australian Homes

A landmark study by Dewsbury et al. revealed something alarming: newer Australian homes are more prone to condensation and mould than older ones.

Why? Because while modern homes are built with more airtight materials, they often lack proper ventilation and thermal design.

Here’s what happens inside many “standard” new builds:

  • Warm, moist air from showers, cooking, and even breathing can’t escape.

  • Poor insulation creates cold internal surfaces.

  • When that warm air meets cold surfaces, condensation forms.

  • And where there’s condensation, mould quickly follows.

The problem is especially bad in homes with:

  • Inadequate insulation

  • No ventilated air cavities

  • Minimal or no mechanical ventilation

This isn’t just bad luck—it’s a building design failure.

The Real Cost of Mould

Mould isn’t just unsightly. It comes with serious consequences:

For your health:

  • Asthma and respiratory conditions

  • Chronic fatigue and brain fog

  • Sinus and skin irritation

For your home:

  • Structural damage

  • Warped cabinetry

  • Ruined plasterboard and finishes

Left untreated, mould can silently undermine your home from the inside out.

Two Hammers Construction builder and designer planning high-performance home

How Two Hammers Builds Differently

At Two Hammers Construction, we believe mould should never be part of a new home. That’s why we design and build high-performance homes that eliminate the conditions mould needs to grow.

Here’s how our approach makes the difference:

  • Continuous Insulation – No cold spots where condensation can form.

  • Ventilated Cavities – Walls and roof systems designed to breathe and manage moisture.

  • Airtightness + Controlled Ventilation – We seal homes properly, then ventilate them correctly to remove moisture instead of trapping it.

  • High-Performance Windows & Glazing – Preventing thermal bridging and cold window panes that attract condensation.

  • Climate-Smart Design – Our in-house design team considers humidity and air quality from day one, ensuring your home stays comfortable and healthy.

Build it Right. Build it for Life.

With rising humidity, extreme weather, and outdated building practices still common, building the “old way” simply isn’t good enough anymore.

Whether you’re planning a major renovation, extension, or a custom new home in the Margaret River Region—Busselton, Dunsborough, Yallingup, Augusta and beyond—make sure mould isn’t part of your future.

At Two Hammers, we’re committed to creating healthy, durable, high-performance homes designed for the unique South West climate. Because a home shouldn’t just look good—it should make you feel good, too.

Ready to Talk About Your Project?

Want to learn more about how we build homes that stay dry, comfortable, and mould-free?
Get in touch with our team today and let’s talk about your next project.

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