Powdered, unmodified thinset mortar will stick to RedGard waterproofing membrane and securely fuse your tile in place. To make sure your tile installation goes well and remains durable, follow these rules: Allow RedGard to fully dry before you begin tiling.

Can I tile directly over redguard?

For tile installations bonding directly to the substrate; strongly recommended to apply at least one full coat of "undiluted" RedGard® to the "dry" primed area and allow to dry completely before tile installation work is to begin.

Can I use tile adhesive on RedGard?

Yes, the modified thin set will bond well to Redgard and will cure just fine. Do not use unmodified over Redgard. You'll get a decent bond but your porcelain tiles will not bond as well.