We have had a couple of Tilers asking about waterproofing balconies lately. There appears to be a product being used in the construction of balconies that is causing some lifting of waterproofing products. Ardex have released a technical sheet on tiling & waterproofing over James Hardie Scyon flooring sheets. Ardex also have an app that you can download for product and technical information. If you are using other brands of waterproofing and having trouble, email email@example.com so we can follow up. There is also a great online resource at www.mastertilers.org where tilers discuss similar issues on the sites forum.