One of the most common technical questions received by Tyvek is design and product recommendations for skillion (cathedral) roof design, installation, and ongoing performance.
The performance challenge arises from the relatively small volume of air in the ceiling space and the difficulty in achieving enough air movement to prevent accumulation of moisture in building elements.
Recently a clause in NZBC E3 that was interpreted as restricting the venting of spaces above insulation has been removed. This change allows for code compliance whilst still providing for air drying ventilation paths.
Globally building science professionals have recognised the importance of roof space venting to prevent moisture accumulation, and for the last 35 years DuPont has been providing roof design and product solutions for skillion/cathedral roofs.
Although DuPont has a hugely diverse building envelope product range, the Tyvek Supro, Pro and Metal have been selected as best meeting the requirements of the NZBC, local construction styles and New Zealand’s climatic conditions.
In a skillion roof, an underlay as part of a comprehensive design, is required to have:
- High water resistance: to prevent liquid water ingress
- High water vapour permeability: Tyvek underlay permeability has been designed to optimise the drying rate of timber
- Air resistance: to prevent moist air from disrupting the insulation performance
- Durability: Tyvek has been used in millions of roofs around the world over the last 35 years
DuPont is proudly represented and distributed by Tyvek in New Zealand, available throughout the country through the merchant network and roofing installation channels.
Priced competitively, easy to lay, durable, tear-resistant and with high UV resistance, Supro, Pro and Metal are the products of choice for design professional and construction teams wanting a solution that provides the performance and durability for the lifetime of the building.