Ceresit CR 65 - Waterproofing Mortar
What is Ceresit CR 65?
Ceresit CR 65 is a professional-grade, cement-based Rigid Waterproofing Slurry designed for creating water-impermeable coatings on mineral substrates. It is the industry standard for internal "tanking" of basements, water tanks, and swimming pools. It protects structures against both dampness and pressurized water (up to 5m depth) while remaining vapour-permeable.
| Technical Specification | Value / Detail |
|---|---|
| Material Base | Cement with mineral fillers and polymers |
| Water Pressure Resistance | Up to 0.5 bar (5-meter head of water) |
| Application Method | Brush (slurry), Trowel, or Spray |
| Consumption (Damp Proofing) | Approx. 3.0 kg/m² |
| Consumption (Pressure Water) | Approx. 6.5 kg/m² to 8.0 kg/m² |
| Drying Time | 24 hours (walking); 3 days (tiling); 28 days (filling tanks) |
| Safety | Suitable for potable (drinking) water tanks |
- Can Ceresit CR 65 be used for basement tanking?
Yes. Ceresit CR 65 is highly effective for internal basement tanking to prevent groundwater ingress. It must be applied to a sound, mineral substrate (like concrete or brick). For basements with active leaks or high structural movement, it is often used as a primary rigid layer before applying flexible membranes. - Is Ceresit CR 65 safe for drinking water tanks?
Yes. CR 65 is non-toxic and certified for use in permanent contact with potable water. It is widely used for waterproofing concrete reservoirs, water towers, and fish ponds without leaching harmful chemicals. - Does CR 65 allow walls to breathe?
Yes. Unlike bitumen-based coatings, CR 65 is vapour-permeable. This allows moisture trapped within the masonry to evaporate as vapor while preventing liquid water from passing through, reducing the risk of internal damp-rot.
Step-by-Step Guide
- Substrate Prep: The wall must be clean and "matte-damp" (saturated with water but no puddles).
- Mixing: Mix a 25kg bag with 6.5L to 7.0L of water (for brush) or 5.5L (for trowel).
- First Coat: Apply the first layer liberally using a stiff brush (masonry brush). Work it into the pores of the substrate.
- Second Coat: Once the first layer is "set but still damp" (usually 1–2 hours), apply the second coat crosswise (at a 90-degree angle to the first).
- Curing: Keep the surface damp for 24 hours using a fine mist spray to ensure the cement hydrates correctly and prevents cracking.
- Pro-Tip on Wall Corners: When tanking a basement, the joint where the wall meets the floor is the weakest point. Create a "fillet" (coved corner) using Ceresit CX 5 Express Cement before applying the CR 65 to prevent the coating from snapping at the corner.
- Pro-Tip for Tilers: If you are using CR 65 in a wet room or shower, allow it to dry for at least 3 days before applying tile adhesive. We recommend using a flexible adhesive like Ceresit CM 12 to bond to the rigid slurry.