Skillion roof design continues to be a popular choice in the New Zealand domestic housing market, however, the limited natural ventilation of these designs is still not receiving the attention needed. There are still new projects that have missed the memo about moisture and ventilation issues in skillion roofs, and most of the time this comes down to not providing sufficient and well-designed ventilation.
When not handled correctly, moisture trapped in the roof space — either from building materials drying out or from living areas below, will undoubtedly result in mould, moisture, structure and insulation issues and consequent problems for the occupants.
In recent years, there has been an increase in new ventilation products such as castellated battens, honeycomb-style PVC battens, ridge and eave vents. These products can help improve the airflow and reduce the moisture problems often seen in small roof spaces.
With skillion roof design, Thermakraft's recommendation is to first prevent moisture from living areas getting into the roof space. Provision must then also be made to ensure that any moisture that does reach the roof space is adequately ventilated out of the roof area. When ventilated type battens are used in skillion roofs, they should be installed below the underlay and above the rafter/purlin. This will increase airflow and reduce trapped air.
Good design along with Thermakraft’s CoverTek range of high strength high-performance synthetic roof underlay’s and Vapor Shield-101 vapour barrier for high moisture control will assist in preventing moisture problems. Thermakraft's technical team works with designers to select the best underlay for each project.
Talk to Thermakraft about upcoming projects to find out which Thermakraft underlay is best for each design.