E2/AS1 Compliance

Specified passive ventilation on architectural plans has become the norm in New Zealand over the past few years. But, we’ve found a small number of roofers and builders are opting out of Vent installation come build time. Our latest article explains why passive ventilation is important to ensure you’re compliant with E2/AS1 (3.5, 3.6) and E3.2.

With more airtightness, homes can become susceptible to trapping moisture in the form of vapour. If this vapour is unable to escape, excess vapour condensates and absorbs into a home’s structure causing dampness, mould growth and rot. In new homes without ventilation, significant mould and condensation can develop within just 1-3 years. We are now seeing this in homes built from 2016 to 2021.

Older homes take a lot more heat to warm up and due to lack of insulation and natural drafts the habitable space cools down a lot faster. When there is a large change in the air temperature at night, the risk of condensation, dampness and mould show up in the living area itself.

In contrast, new homes retain warmer internal air with less heat loss, which shifts the dew point to the colder side of the insulation. This moves the risk of condensation, dampness and mould into the roof cavity. If vapour is unable to pass through these cavities when the temperature drops, excess vapour quickly condensates and saturation begins.

Without proper airflow, which can be achieved easily with Vent passive ventilation, there is a risk of non-compliance with E2/AS1 section 3.5 and 3.6. The code specifically requires the mitigation of moisture in cavities.

Now that homes are more energy efficient, so too is the risk of moisture trapped in cavities without adequate moisture management systems.

Failing to include adequate ventilation to allow your builds breathe, not only risks non-compliance with E2, but also exposes you to potential liability.

America, Europe, United Kingdom and Australia all recognise the importance of passive ventilation to create a breathable, future proofed new build and their building codes all include prescribed free flow air requirements.

Positive pressure systems don’t work well in new builds without gaps in the construction to allow stale air to exit or fresh air to enter the roof cavity. Typically, balanced pressure systems – which mechanically create two way airflow from inside to outside, are not specified due to cost, so your build is still at risk of moisture build up.

There are also user risks for controlled ventilation. Homeowners or renters can easily turn off the ventilation system leaving your project prone to moisture build up unintentionally.

Vent systems are passive systems that protect the homes’ structure to ensure it remains a healthy home long into the future.

Our systems are compatible with steel and timber fascias/roof structures and work across all roof types. The system cleverly lets air flow in but keeps large bugs and debris out of the roof space. Our products include a peel off backing to reduce the need for excessive nails and screws. It can be easily cut to size by hand and is discreet. Giving your roof space airflow without disrupting the flow and design of a home.

These six minute videos demonstrate how easy it is to install Vent onto a skillion or truss roof. The truss roof video also includes how to install a baffle to reduce your heel height and offset your Vent system costs.

We’ve seen several cases where roofers are returning to new builds to fix installed roofs because of reports of leaking. The roof isn’t leaking, but moisture is dripping down the walls from the roof worrying homeowners that their new roof is leaking.

We’ve seen a growing industry trend with roofers insisting on the inclusion of passive ventilation in the roofing systems of new builds to avoid being called back because of perceived leaks that are the result of moisture build up due to dew point condensation and/or inadequate airflow.

Not convinced to add extra costs to your budget? Vent’s passive ventilation systems are cost effective and easy to install meaning minimal effect on your overall labour costs. Check out our videos about installing Vent to see how simple the install process is.

In fact, the cost of ventilation can be offset in most truss roofs by reducing your heel height and cladding costs with a Vent Eaves Baffle. An Eaves Baffle means you can reduce the heel height of your build while remaining compliant with NZ4246, plus making room for more insulation coverage towards the roof edges. Read more about heel height and offsetting your Vent costs.

We understand the challenges of the building industry in New Zealand and that budgets are important. But, Vent systems are cost effective, from as little as $1500+gst to ensure your projects are future-proofed and built to last.

Modern building regulations are focused on healthy, energy efficient homes, but New Zealand’s building code does not yet reflect the long term effects of creating a completely airtight home without considering the ramifications of uncontrolled moisture management.

Give us a call to test Vent in your next build. We can talk you through how to offset the costs of our system, and why you need to install passive ventilation in the roof even with a home ventilation system in place.