Part Two of our building surveyors’ review into the 2019 edition of the NCC focuses on the changes to the Health and Amenity provisions.
Condensation management, and risks associated with water vapour, have been identified as an ongoing issue in the construction of dwellings in Australia. The ABCB released a non-mandatory handbook in 2014 for building surveyors and designers relating to condensation in buildings and water vapour control. Although the handbook provides a significant amount of background information on condensation development, there was no acceptable construction practices or guidelines for management and control and how to implement them.
The 2019 edition of the NCC has now adopted a new Performance Requirement (P2.4.7) and deemed-to-satisfy provision (3.8.7) solely dedicated to condensation management within Class 1 buildings.
The performance requirement states “Risks associated with water vapour and condensation must be managed to minimise their impact on the health of occupants”. A verification method has also been adopted to meet the general performance requirement. The verification method states;
“Compliance with P2.4.7 is verified when modelling that assesses the effect of –
(a) indoor and outdoor temperature and humidity conditions; and
(b) heating and cooling set points; and
(c) rain absorption; and
(d) wind pressure; and
(e) solar radiation; and
(f) material hygrothermal properties;
determines that moisture will not accumulate –
(g) interior to the primary water control layer within a building envelope; or
(h) on the interior surface of the water control layer,
The deemed-to-satisfy provision provides an acceptable construction practice to address the performance requirement by providing either a pliable building membrane or cavity to an external wall, increasing flow rate and ensuring correct discharge of exhaust systems and ventilation of roof spaces is sufficient.
In our introductory blog to the NCC 2019 we discussed the increased number of verification methods and the trend in building surveyors using these methods to address the performance requirements. As it is expected the acceptable construction practices will be further increased in future editions of the Code, we will see an increased need in modelling via a verification method in climate zones with a decreased impact from condensation.
If you would like more information on how the adopted provision will effect your next project please contact one of our building surveyors on 0411 648 159 or via e-mail admin@specialisedbuildingsolutions.com
Further information on health and amenity and other building surveyor matters can be found on our website www.specialisedbuildingsolutions.com.au
