Express Course

How to fix EPS insulation boards with PU adhesive

Learn how to install insulation boards with Ceresit CT 84 PU foam adhesive and fix them with mechanical fasteners.

Know upfront

Tools needed

  • a PU foam dispensing gun
  • a drill and a power screwdriver
  • a fastening system for EPS boards

CRUCIAL to know

  • application from -10˚C
  • anchoring after 2 h
  • 1 container of CT 84 adhesive = 10 m2 of EPS  insulation


PU foam application on EPS boards

The container should be intensively shaken for several seconds, then the valve protection cap should be removed and the container, with the valve kept upwards, must be attached to the gun. The valve of the gun should be twisted off. Now you can open the valve and release the adhesive.

CT 84 should be applied along the board with the distance of 2 cm from the edges and 1 strip running along the board parallel to its longer sides. CT 84 on foundations must be applied in 5 strips along the shorter side of the board, with the distance ca. 5 cm from the edge.

Attaching EPS boards to the wall

After the CT 84 application, press the board to the wall for 2 to 4 minutes, using a long float. The surface of the fixed boards can be corrected for up to 20 min since their wall fixing. High humidity can cause faster bonding of CT 84. The boards must be fixed tightly one to the other, in the brickwork manner. If there are any gaps, you should fill them up with PU foam.


How to use dowel fastenings properly

All the fixings should be designed for the type of wall material (concrete, blocks etc.). The flange diameter of fixings for EPS boards is minimum 6 cm. An anchoring depth of minimum 6 cm, in case of solid building material and 8 cm in case of porous building materials, is needed. Anchoring should be done not earlier than two hours after fixing the boards with CT 84. For the installation of dowel fastenings use a hammer drill or a standard drill. Remove all the dust from the holes. At least four anchors should be fixed per one square meter. All fixings should be acc. to ETAG 014 approvals – guideline for mechanical fixings.

The polishing of the insulation material should be done on those areas where the slabs are not faced e.g. corners, joints. The General idea is to reach as much even surface as possible, before applying a reinforcing layer. After polishing, remove the dust from the facade.

Installation of anchors with plastic flange

You need to cut out the round cap of the EPS board. There will be lots of polystyrene particles around, which need to be removed with a vacuum cleaner so they don’t disturb further work. Then you drill a hole through the insulation board deep into the wall and put the anchor inside. Now you can screw it in with a power screwdriver. Some anchors can be hammered as well. Cover the anchor with the previously cut EPS cap.

Installing anchors with a plastic head and prefabricated EPS caps

This system is more simple, as the polystyrene caps are already prefabricated. Just drill a hole for the fastener, place it inside and screw it in deep enough, so that the polystyrene cap does not overhang the face of the EPS board.


Installing the fasteners with a flange.

Installing fasteners with plastic heads and prefabricated EPS caps.


How many anchors per one meter of insulation?

The minimum number of fixings is ≥ 4 units per 1 . The installation of additional fixings is determined by the wind load on the facade.

The number of fixings should be increased in the corner areas of the buildings, which depends on the width of the building.