Im a contractor/installer hired to rebuild an external balcony. Sub floor is being formed used 22mm thick t&g cement boards. The specification requires a paint-on waterproofing system / product to be be used that is compatible with a cement based exterior grade tile adhesive. This will be used to form a thin 4mm thick bed to then fix an uncoupling / anti-fracture matting prior to finishing with a 10mm porcelain floor tile. Can your recommend one of your products for this application?