Green roofs have exploded in popularity over the last decade. Originally the domain of higher-end sustainable commercial developments, they’re now increasingly to be found on residential homes throughout our cities and towns. And with good reason. Green roofs are an incredibly effective way to raise the sustainability profile of a dwelling - providing insulation for the residence, reducing the urban heat island effect, and even providing additional habitat for nativa fauna. Oh, and they look great.

But of course, putting a garden on top of a roof comes with its challenges. The weight of a garden is considerably more than the weight of some corrugated iron or tiles. The chemical makeup of the substrate can react with the underlying roof material causing premature degradation. And, of course, if the roof is not perfectly waterproofed, water damage can quickly become a major issue.

It’s with a deep understanding of the waterproofing requirements for green roofs that Sika rolled out their Sarnafil® G 410-15 L PVC membrane, backed with Sarnacol®-2170 contact adhesive, for a residential green roof in Canberra. Sarnafil is a multi-layer, synthetic roof waterproofing sheet based on PVC, with a glass non-woven inlay. It’s a hot-air weldable roof membrane that has been specifically formulated for direct exposure and designed for use in all global climatic conditions.

The membrane was expertly applied for the Canberra project by the Specialised Waterproofing and Trades Group (SWAT), who have been expertly trained in the delivery of the Sarnafil system. After being adhered to the flat part of the roof, the team attended to corners and edges to ensure that any pooling water could not seep in higher up in the roof box. Once the process of laying and adhering membrane to all areas was complete, the team filled the space with water containing bright yellow dye. This enables clear visualisation of any leaks that may be present, allowing them to be treated immediately. In addition it allows the team to easily test that the water spouts are providing adequate egress for excess water flow.

It’s difficult to overstate the importance of roofing membranes in contributing to sustainable design across a wide variety of roof types - and particularly a membrane as versatile as Sarnafil. In addition to the air quality and insulatory benefits of a green roof, Sarnafil is an ideal membrane for blue roofs (used to collect, store, and release rainwater), or blue-green roofs (a combination of the two). 

Further, membranes can contribute to the sustainability profiles of dwellings with more traditional roof types. Specifying a membrane with high solar reflectance can help in reducing the urban heat island effect, and reduce the absorption of heat, requiring less energy usage within a dwelling. They can be used to aid rooftop solar systems, and maintain waterproofing integrity around panel installation. Finally, they can be applied to warm roof types (directly onto the insulation layer on top of the roof), avoiding the need for additional ballast or screed.

This Canberra residence is a fine example of green roof best practice, and the integrity of the Sarnafil membrane ensures that the residents of the property will continue to reap the sustainability benefits as they watch their roof flourish for years to come.