Changes to ventilation requirements in the National Construction Code 2019
What does the Volume 2 of the National Construction Code say about ventilation of roofs?
From the 1st of May 2019, the National Construction Code is introducing a new section titled ‘Condensation Management’ which includes an important change to the acceptable construction practice for the management of internal moisture and roof ventilation. This change will affect all Building Permits approved after the 1st of May 2019 and requires the ducting of all internal moisture sources to external air OR the ventilation of the roof space if internal sources of moisture are not external ducted.
For residential (Class 1 construction - Volume 2 NCC2019 Clause 220.127.116.11 Ventilation of roof spaces), these changes state that where an exhaust system is installed in a kitchen, bathroom, sanitary compartment or laundry discharges directly into a roof space, the roof space must be ventilated to outdoor air through evenly distributed openings. This can be achieved with installation of roof ventilators in accordance with the table below, located not more than 900 mm below the ridge or highest point of the roof space, measured vertically, with the remaining required area provided by eave vents.
How to Comply with the National Construction Code 2019
A) Exhaust directly into the roof space and use Bradford’s natural roof ventilation in combination with eave vents to exhaust moist air
B) Direct ducting of internal wet rooms (bathrooms, kitchens & laundries) to outside air
Volume 2 NCC2019 Clause 18.104.22.168 Ventilation of roof spaces
Based upon the pitch of the roof and ceiling area of the house in square metres area, the required number of roof ventilators and eave vents can be
selected from the table below: