Ceresit CT83 - Polystyrene Adhesive - 25kg
What is Ceresit CT 83?
Ceresit CT 83 Strong Fix is a high-performance, cement-based Adhesive Mortar specifically designed for fixing Expanded Polystyrene (EPS) boards to external walls. It is engineered for superior initial grip and high bond strength, making it the essential first step in the Ceresit Ceretherm ETICS (External Thermal Insulation Composite System). Note: CT 83 is used for fixing only; a separate basecoat like Ceresit CT 85 is required for the reinforced mesh layer.
| Technical Specification | Value / Detail |
|---|---|
| Material Base | Cement-based with mineral fillers and resins |
| Primary Use | Fixing EPS (Polystyrene) boards to masonry |
| Initial Grip | Very High (Instant grab) |
| Consumption | Approx. 5.0 kg/m² |
| Adhesion to Concrete | > 0.5 MPa |
| Open Time | Approx. 20 minutes |
| Application Temp | +5°C to +25°C |
- Can I use Ceresit CT 83 as a basecoat for mesh?
No. Ceresit CT 83 is a dedicated adhesive. It is formulated for maximum bond strength to the wall, but it does not have the specific flexibility or fiber reinforcement needed for a basecoat layer. For the mesh-reinforced layer, you must use a universal mortar like Ceresit ZU or Ceresit CT 85. - How long does Ceresit CT 83 take to dry?
Under standard conditions (20°C and 60% humidity), CT 83 will set sufficiently within 24 to 48 hours. After this period, you can proceed to mechanical fixing (installing insulation pins) and applying the basecoat. - What surfaces can I use CT 83 on?
It offers excellent adhesion to all standard mineral substrates, including brickwork, concrete, aerated blocks, and cement plasters. For highly absorbent walls (like old brick or breeze blocks), we recommend priming first with Ceresit CT 17.
- Substrate Prep: Ensure walls are clean, dry, and structurally sound.
- Mixing: Pour a 25kg bag into approx 5.5L of clean water. Mix with a low-speed drill until smooth.
- Perimeter & Dab Method: Apply a 3–4cm wide bead of CT 83 around the edge of the EPS board and 3–6 "dabs" in the center.
- Board Placement: Immediately press the board against the wall. The "perimeter" bead ensures that air cannot circulate behind the boards, which is vital for thermal efficiency and fire safety.
- Alignment: Use a long spirit level to ensure the boards are perfectly flat before the adhesive sets.
- Pro-Tip on Fire Safety: Always use the "Perimeter" (border) method when applying CT 83. Do not use the "Dab only" method, as this creates air gaps that can act as a chimney in the event of a fire.
- Pro-Tip for Summer: In very hot weather, CT 83 can dry too quickly. Dampen the wall slightly with water or use a primer to prevent the wall from "sucking" the moisture out of the adhesive too fast, which can weaken the bond.
CERESIT® CT 83 mortar is designed to apply EPS-boards within CERESIT ETICS with a light-wet method CERESIT Ceretherm. CT 83 mortar is used for applying to the newly erected objects as well as the buildings to be thermo renovated. The applied boards require additional fixing by means of mechanical anchors, i.e. proper expansion pins made of plastic. CERESIT CT 85, CT 87 or CT 100 mortar should be used to apply fibre glass armoured layer on the EPS-boards. Available pack size: 25 kg