Features and Benefits

Ceresit CO 81 is for drill hole injections and surface waterproofing


  • Deeply penetrating
  • Prevents capillary rise of moisture
  • Increases surface strength
  • Produces water-repellent surfaces
  • Reactive
  • Amount required (depending on type of use):
    - Injection 10-15 kg/m2 (wall cross section)
    - Slightly absorbent substrates 0.15 kg/m2 (dilution 1:1)
    - Normally absorbent substrates 0.4 kg/m2

Read More

Ceresit CO 81 is used for pressurised and non-pressurised injections into the existing brickwork in order to seal capillaries and fine cracks and prevent further capillary rise fo moisture. It can also be used for sealing external and internal faces of walls.
CO 81 is also suitable for waterproofing of buildings (especially basement walls) and structural components against ground moisture and non-pressurized water in combination with other Henkel products, e.g. CR 65 Waterproofing Slurry. It can also be used as primer before applying bitumen thick coatings – CP 43, CP 44 and CP 48. The product can be applied on damp surfaces.

Step by step

Substrate preparation


Before or after drilling the bore holes, chip off the damaged plaster for a minimum of 80 cm beyond the visible damp and salt area. Chemical injection is not suitable for gypseous brickwork. Therefore, gypseous mortar or plaster must be completely removed. If necessary, clean the brickwork mechanically. Pressureless injection: Pressureless injection is particularly suited for slightly damp or damp brickwork. Drill holes for the silicification fluid with a diameter of 30 mm, an average of approx. 12 cm apart and a slope of at least 30° (not more than 45°). Pressure injection: Pressure injection is especially suited for saturated substrates. Drill holes of 12 to 18 mm diameter (depending on the type and size of injection tube used), an average distance of approx. 12 cm and a slope of approx. 30°. At a slope of 30°, the depth of the bore holes should be equivalent to the thick- ness of the brickwork to ensure that 5 cm of the walls to be treated are not drilled through. Drill the holes in one or two rows. In the latter case, drill two staggered rows of holes on top of each other, with the holes approx. 8 cm apart. Use an electropneumatic drill or a core drill with as little vibration as possible. Position the holes so that at least one course joint is penetrated. Walls of more than 60 cm thickness and wall corners must be treated on both sides. Walls with larger cavities or cracks, and walls made of hollow blocks or loosely filled with mortar and stone in the core must be grouted with CR 65 sealing slurry (8 l of water on 25 kg) before injection of the silicification fluid. After the slurry has hardened, re-drill the holes. After drilling, blow the bore holes free of dust.



Inject CO 81 without pressure from feed vessels with an infiltration time of at least 24 hours. In the case of pressure injection, use suitable devices and a pressure of 2 to 7 bar. Next day, fill the holes cavity-free with CR sealing slurry (approx. 5 to 6 l of water). Supporting measures after producing the horizontal damp course, replace the chipped off plaster by applying a layer of CR 62 repair plaster or CR 63 universal repair plaster (thickness at least 20 mm). Apart from these sealing measures, the external cellar wall sealing must be renewed or repaired where necessary. Any structural defects must be rectified during the overall repair work. If possible, install a drainage system to ensure rapid run-off water.