PU adhesive foam for bonding and insulating
PU foam insulates, seals and bonds. As the name suggests, PU adhesive foam adheres very well. This is why it is also called PU adhesive. It is most frequently used for mounting thermal insulation composite systems (TICS).
About 80 percent of all façades in Germany are insulated with PU foam. Professionals use PU adhesive foam to attach the insulation panels to masonry, façades, cellar ceilings and flat roofs. PU adhesive also has very good thermal insulation values of between 0.26 and 0.04 W/(mk). The TICS adhesive foam acts as a second insulating layer between the insulation panel and the wall of the building. As a result, the insulation can be mounted free of thermal bridges.
Advantages of PU adhesive
The advantage of polyurethane adhesive foam over other cement-based adhesives is that it hardens quickly and the fitter does not require any additional tools. After just two to three hours, work can continue on walls mounted with PU adhesive. In contrast, cement-based adhesives must dry out for three to four days before the next work steps are possible. When choosing the right adhesive foam, manufacturers recommend using foams that do not expand too rapidly. This ensures that the insulating elements do not shift in an uncontrolled manner whilst the PU foam hardens and expands.
Observe the building approval
It is also important to check that the foam is officially approved for use with the TICS. Approval is also required for PU adhesive foam to be used for grouting non-load-bearing walls. Partially-collapsing foams are the right choice in this case.
How you can avoid thermal bridges
While PU foam is optional for TICS mounting, it is a must for filling open joints. To avoid thermal bridges on the façade, specialists must install the insulation panels precisely with tightly pressed butt joints. However, regardless of how precisely the panels are installed, joints cannot always be avoided. These need to be filled in carefully later on, so that the 'full insulation' can live up to its name.
Adhesive mortar may never be used for filling because this will create thermal bridges. Instead, smaller gaps are insulated with PU foam. Likewise, these need to be approved by the manufacturer of the TICS for this application. In the case of larger gaps, polystyrene strips are cut to size and placed in the joint.
Other application options of adhesive foam
In addition to mounting thermal insulation systems, PU adhesive can be used quite universally. Two examples of this are bonding non-load-bearing interior walls and bonding flowerbed edgings made of natural stones. Adhesive foam replaces classic cement.
Adhesive foam is supplied in customary pressurised cans as adapter foam or pistol foam. Like all other PU foam cans, the spent cans can be returned free of charge for recycling at PDR.
PU adhesive foam should not be confused with assembly adhesive. The latter is supplied in plastic cartridges or tubes. Assembly adhesive is always your first option if you want to avoid drilling, screwing and nailing; for example, when mounting a mirror in the bathroom. Assembly adhesive is available in various chemical compositions, including a PU-based composition, but it is not actually considered a PU foam.