We recommend removing any previous applied products before applying PermaFlex to ensure the best possible adhesion. Understand that surface preparation is 75% responsible for waterproofing success of a first time application. If you want a completely waterproof basement, it’s best to remove all paint and previous coatings so you can apply PermaFlex directly to the concrete. By starting with completely bare, clean, and dry concrete free of any paint, coatings, or crumbling debris, Sani-Tred can fully adhere to the surface, penetrate deep into the pores, and harden, while remaining flexible, to fully waterproof your concrete.