Skillion roofs are an increasingly popular option in contemporary New Zealand architecture, with many new home designs featuring this style. While skillion roofs offer a range of benefits — including simple installation of eco-friendly solutions like solar panels and skylights — there can be potential moisture issues as, once the roof is finished, the roof space is generally inaccessible and has little natural ventilation.

In skillion roofs, the roof cladding and ceiling run parallel, typically within 300mm of each other. This small roof space can accelerate problems with moisture, as while a 45m² gable roof space at a height of 1.4m would take roughly 1 hour and 40 minutes to fill with airflow from the living space below — allowing time to dilute the moist air with ventilation — a skillion roof with the same area would take about 10 minutes to fill. When temperatures fall below dew point, the moist air can form condensation which may wet the insulation, or be absorbed by the framing or underlay, potentially leading to the growth of mould and mildew and hindering the performance of the insulation. With this in mind, it is important to consider both the type of insulation and the ventilation system used in a skillion roof to avoid moisture damage.

Choosing an insulation product made from moisture resistant materials, such as polyester, is a great way to prevent moisture damage in skillion roofs. GreenStuf Skillion Roof Blanket is made from 100% polyester fibre which has been tested and shown to absorb only 1.1% of water vapour by weight, when exposed to an atmosphere of 49°C at 95% relative humidity for four days. GreenStuf Skillion Roof Blanket has also been tested for microbial resistance in accordance with ASTM G21, and no microbial growth was found after exposure to an environment of 30°C at 90% relative humidity for 28 days. Alongside a good ventilation system to ensure water vapour isn’t absorbed by framing or other building materials, GreenStuf Skillion Roof Blanket will perform for at least 50 years — ideal for a skillion roof space, as retrofitting insulation in skillion roofs is difficult and can require re-roofing. Making the most of this modern roof style means ensuring all aspects of the roof are fit for purpose and designed to last.

GreenStuf Skillion Roof Blanket is supplied in pre-cut pads for easy installation, with a range of thicknesses to meet R-Value requirements. Get in touch with GreenStuf today to specify GreenStuf Skillion Roof Blanket for upcoming projects.