How to plaster a Penoplex (EPS) facade? Simple tips to prevent plaster from falling off

The name of Penoplex thermal insulation has become a household name for extruded polystyrene foam (EPS). But this brand name is one of the manufacturers. There are other brands as well. For example, in our city, another manufacturer produces EPS under the Termit brand. But for simplicity, in this article we will talk about Penoplex, meaning all manufacturers of EPS.

Penoplex is often used to insulate the facades of houses. If there are no questions about the installation technology itself (glue plus plastic dowels), then there are a lot of questions about the reliability of fixing the joke facade on this insulation. Especially when you see pictures like this:

A number of other examples can be seen in the video:

In these examples, mesh plaster does not adhere to the EPS. Although, such plastering work on Penoplex is a common technique for creating an insulated facade.

What could be the reason why someone's plaster falls off from Penoplex? It can be seen that in these examples, for some reason, sufficient adhesion of the plaster with the insulation did not occur, there is no reliable adhesion.

This could have happened due to poor quality plaster mix. Or there was a release of moisture from the walls through the cracks in the insulation. It condensed on the inside on a layer of plaster and over time, a few years later, peeling began. Or the facade itself is constantly wet (a house without gutters).

The plaster seems to hold on to the insulation, but it is easy enough to tear it off. To prevent this from happening, you can use two methods (optional).

1. Cover Penoplex surface with concrete contact. This is a special primer filled with coarse quartz sand. The binder is acrylic polymers (as in paint). They have adhesion, adhesion to any surface is much higher than that of plaster. A day after painting with concrete contact, you can plaster the facade. Concrete contact is also used when laying tiles on smooth concrete walls. Additional materials and painting are both additional costs and time. Better to use the second method.

2. Increased adhesion to Penoplex can be achieved by mechanical processing of the insulation with a metal brush.

On such a surface, the plaster will hold much better. Some even conducted an experiment before plastering the facade of their home. Example from the link: https://vk.cc/c5hFNj

Instead of a brush, you can walk with a hacksaw blade on wood. The process will go faster.

It is also important that all gaps between the Penoplex sheets are foamed. If there is a wasteland in the masonry of the wall, then in this place there will be an increased release of water vapor from the room. This will lead to the accumulation of moisture under the layer of plaster and it can peel off in this place, as in the examples above. From this it is clear that when insulating with Penoplex, the walls should not breathe. Ventilation must breathe.

It is also important that the wall blocks themselves are dry before insulation. Those. a stone house must withstand from six months to a year after construction. Installation of insulation must be done in dry weather.