What is a Ventilated Cavity?

In simple terms, a ventilated cavity is an air space between the cladding of a building and its structure. This space allows the building to "breathe," circulating air and carrying moisture away. This is crucial to avoid issues like mould, rot, and other moisture-related problems. 

It’s a technical topic which is why we’re once again joined by Dr Cameron Munroe, who breaks down the nitty gritty of ventilated cavities.  

Cam explained that inheating-dependant climates like Melbourne or Canberra, building materials need to allow water vapour to escape. Unfortunately, traditional methods sometimes trap this vapour. A ventilated cavity helps in solving this by moving vapour out through a well-ventilated air space.

We've noticed and discussed how modern weatherboards differ from older ones. The primary reason? Changes in building techniques and materials. Old hardwoods have been replaced with softwoods, which absorb more moisture and have less tolerance. With improved insulation, drying potential decreases, making material choice vital for moisture management.

Different cladding types may require varied cavity depths for effective drainage and ventilation. It's essential to consider both ventilation (for air/moisture) and drainage (for liquid water). Thickness of battens used in cavities needs attention, as they play a role in air circulation and moisture drainage.

Cameron suggests that while small gaps can handle drainage, air circulation requires larger cavities. Achieving the right balance between these is key in construction.

So how do you choose the right cladding material for your climate? Well, buildings in colder regions require more consideration in cladding and batten selection to prevent moisture issues. We can model these factors to make informed decisions about batten thickness and design.

1. Cavity Depths: Consider a standardised cavity size, like a 70mm, which can work across various applications and climates.

2. Drainage vs Ventilation: Focus on creating effective drainage and ventilation solutions. Think about using metal mesh for venting and drainage to prevent clogging while allowing air to flow freely.

3. Durability of Materials: Choose materials designed to withstand climate changes and prevent long-term degradation.

It’s also important to remember that your roof is essentially a wall at an angle. So, similar principles of ventilation and drainage apply. Make sure your roofing system is designed to handle moisture effectively. Avoid using products like Anticon under roof sheets as they can degrade over time and block airflow.

So make sure you’re considering the climate and how it'll impact moisture and heat within your building's interior. Ensure you have the right ventilation and drainage strategy to manage moisture efficiently!

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