Key Facts

CL 51 "EXPRESS 1-K" sealing film

Flexible 1-component sealing film  for use under tiles and slabs in domestic areas.


  • Admitted for use by the construction supervising authority A1
  • Waterproof
  • Fast drying
  • Crack-bridging
  • For indoor use
  • For wall and floor application


CL 51 1-component sealing film produces seamless and jointless sealing under ceramic coverings in damp and wet areas inside (e.g. in private bathrooms, toilets, kitchens). In the case of floor constructions with insulating layers CL 51 is applied directly onto the load-distribution layer (screed). Also suitable for use on heated screeds.

Step By Step


Check that the substrate is dry, solid, load-bearing, dimensionally stable and clean, free of substances which can cause separation (e.g. separating agents, loose particles, dust, efflorescence, dirt). If needed, prime them with CT 17, CT 19 or CN 94. Refer to the Technical Data Sheet!

Application - first layer

CL 51 is applied undiluted using a lambskin roll, brush or spreader. To produce a water-proof protective layer at least 2 coats with a total thickness of min. 0.5mm are required (check local regulations for minimum thickness). Expansion and edge joints must be sealed off with CL 152 or CL 82 Sealing Tape, for wall connections and floor drains use Ceresit Wall and Floor Sealing Collars. The sealing tape or collar is placed into the first coat and embedded with the second sealing coat

Application - second layer

After approx.2 hours, the second layer of CL 51 can be applied. About 4 hours after application of the second coat the surface is ready for covering with a certified adhesive mortar, e.g CM 29 or CM 17.