Lead Free Flashing for Safe Water Harvesting

Around chimneys and other roof penetrations lead flashings are traditionally used to create a watertight seal, but if poorly maintained lead flashings can cause major problems for tank water systems. There are now some safer alternatives.

The widespread public perception is that rainwater is safe to drink, and in most areas of Australia, the risk of illness arising from consumption is low “provided the water is visually clear, has little taste or smell and the storage and collection is via a well maintained tank and roof catchment system”.

Alongside local industry and very heavy traffic emissions, lead has recently been highlighted as another possible source of contamination, the argument being that poorly maintained roofs and gutters result in the leaching of lead into roof run-off; made worse by water made acidic by materials such as leaf litter.

In response to consumer concerns and government testing, many roof waterproofing products are being developed as alternatives to the high volume of lead flashing used by the building and plumbing industry.

The word lead conjures up a lot of emotion, there is lead in petrol, lead in paint, and lead in pipe and plumbing fixtures; however, lead is thought of as the major source of water tank contamination.

Testing and assessing lead hazards is essential if there is a potential risk from lead. Isolating lead hazards or lead processes is critical to reduce risk or water contamination in the household.

The Building Code of Australia 2006 (BCA) Volume 2, Part 3.5.1, prohibits lead flashings to any part of a roof that catches potable water. Lead flashing is commonly used on roofs where stepped flashing is required, for example where a roof is flashed at the junction of a masonry exterior wall.

Through extensive research CSIRO indicates that lead sheet failures are related to poor installation. The amount of roof flashing in a total roof area determines the degree of run-off caused by the elements.

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Since 1January 2007, new houses in south east Queensland must comply with Part 25 of the Queensland Development Code and the Public Health Act 2005, section 59 which stipulates that lead or any substance that contains lead, must not be part of a roof system coming in contact with potable water.

As a result the many alternatives to lead roof flashings now include Wakaflex, malleable coated aluminium; malleable zinc; colorbond and zinc aluminium.

Combined Group has developed a lead-free flashing alternative called Wakaflex manufactured by LaFarge Roofing, because, as director Joby Cronkshaw explains, regulations and codes determining the permitted use of lead flashing do not ensure safe rainwater supplies.

“Currently the code stipulates that you must not use lead flashing when a new building is being built and where the building will have a rainwater tank installed.

“At the moment legislation, regulations and Standards do not adequately ensure lead-free tank water or stormwater. Changes to the Building Code take years to happen and the household owner is simply expected to know that they are responsible for the tank’s water quality and to take appropriate action.

“The majority of houses in Australia currently feature lead flashing. At present, legislation affecting the use of lead flashing does not differ from state-to-state, nor is the sector controlled by national regulation. The Australian Building Code is to my knowledge, the only code that affects the use of lead flashing.

“Lead pollution of stormwater is not yet on the radar. The government seems to trust that tank water owners will locate the little guidance that is available, and to follow it. The Water Services Association of Australia (WSAA) and enHealth provide a number of recommendations about avoidance of lead containing materials and guidance on all aspects of tank water quality. For instance, it recommends removal of lead flashing from the roof collection area prior to installing a tank.

“Lead flashings are ubiquitous and many people are unaware of the lead-free alternatives. We believe that lead affects the quality of harvested rainwater which is why removal of lead flashing is recommended prior to harvesting rainwater.

“With all this in mind, we have developed Wakaflex, which is a lead-free alternative to conventional roof flashings. Wakaflex is flexible lead free and adhesive flashing designed to suit all abutment flashings. It can be used with all roofing materials with no run-off or contamination issues”.

According to Joby, lead-free flashing has many advantages over traditional lead, for those working in the construction industry.

“Wakaflex can be used for all wall abutments, chimneys and other rising parts of structures such as dormers. Its inert qualities mean that Wakaflex can be installed with all roofing materials and will not contaminate any run-off being collected and used for domestic purposes.

“Wakaflex can be laid to professional Standards using only very basic tools. The aluminium mesh insert achieves a permanent and close fit to all roofing profiles, and the sealed edge of the flashing provides excellent protection from wind driven rain and dust penetrating the roof space.

“The most beneficial feature of Wakaflex is that it is non-toxic and therefore safer on installers and more importantly on the environment. It is also a lightweight and simple material to install and a valid alternative to lead, zinc and copper roof flashings.” Other than the environmental benefits, Wakaflex is aesthetically pleasing. Its surface can be painted to match the household roof and surrounding materials. Wakaflex is compatible with conventional acrylic house paints which do more to ensure its longevity.”

Find out more about Wakaflex lead free roof flashing, including product features.

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