An international regulatory perspective – for class 1 and 2 buildings

Condensation is a complex and inter-connected problem relating the complexities of the modern built fabric, changing legislative requirements, and increased consumer expectations of thermal comfort within housing. Many factors within the design, construction and building occupation compound and confound the problem. When this phenomenon is not well understood, the law of unintended consequences becomes manifested. Since 2007, research by the School of Architecture and Design (Utas) has identified many assemblages that lack holistic vapour management consideration. For example, low-pitched roofs can accumulate droplets under the sarking that drip onto ceilings, uninsulated recessed downlights become a condensing thermal bridges and allow for vapour transport between conditioned and unconditioned zones. Top and bottom plates become thermal bridges for condensation to form in ceiling cornices and wall skirtings, BAL rated roofs become sealed to exclude cinders but also obstruct ventilation and retain moisture.

Over the past decade the research team has provided ongoing support and advice to design and construction professionals and regulators. More recently, in 2014 and 2016, the research has included an extensive literature review of experiences and built fabric regulation in other developed nations. This research has included significant collaborative relationships with building material manufacturers, state and federal government agencies and BRANZ. Most recently research has included a scoping study of the ‘condensation problem’ for the Australian Building Codes Board.

This paper will discuss developments in built fabric regulation that have occurred in New Zealand, the United States, Canada, United Kingdom and the European Union. It will show a steady and significant increase in international regulatory requirements since 1995. The paper will also discuss the differences of approach to what is an acknowledged design and construction challenge for better thermally performing buildings in all climate types.