Repair of peeling plaster on the facade of the house

Recommendation points

• The walls are cracking – what is the reason?
• When you need to solve a problem “from the inside”
• Types of damage and adequate methods for their elimination
• Repair of the base reinforcement layer
• Elimination of destruction of the decorative layer
• Will surface strengthening help?

Today we will try to understand the reasons for such a phenomenon as cracking and peeling of plaster on the facade of the house, as well as get acquainted with the main methods of bringing the facade finish to an acceptable form, allowing us to prevent the destruction of plaster in the future..

The walls are cracking – what is the reason?

The appearance of cracks can be the result of both insufficient strength of the finishing layer on a moving base, and insufficiently reliable adhesion between layers. Depending on the materials used, the type of insulation and the method of preparing the base, several of the most common reasons can be distinguished..

The most common reason is the formation of condensation in the structure of the finish. One of the prerequisites for this is the disdain for the primer. A wet facade is a multi-layer structure, and it is not for nothing that manufacturers recommend dedusting each layer of finishing coated with adhesion-enhancing compounds. In places with poor adhesion of layers, moisture accumulates, which does not have time to evaporate. This leads to the formation and enlargement of cavities: during cyclic freezing, water destroys the binder. Well, drying out and cracking of the exfoliated finish is a completely natural consequence. Therefore, when applying plaster to the facade, you need to strive for maximum homogeneity of the coating..

Another reason for the appearance of cracks can be the high mobility of the base, or more precisely, the inadequacy of the material characteristics to the conditions of use. This error is most typical when decorating frame houses and log cabins. It is necessary not only to give time for the shrinkage of the foundation and enclosing structures, but also to equip a damper layer, as well as a sufficiently strong and rigid crust of the reinforced base.

In some cases, laminar shifts in the supporting layer of the wall can be the cause of plaster flaking. They appear as a result of insufficient strength of the binder solution, sometimes due to the destruction of the concrete foundation. In such cases, cosmetic repairs will do nothing – such destructive effects cannot be eliminated without serious intervention in the supporting structure of the house..

When you need to solve a problem “from the inside”

The most striking evidence of the insufficient strength and stability of the walls is the wide vertical cracks appearing on the axes of the concentration of loads arising from the resistance of the support. For example, with a muddy (sagging) corner of a building, cracks propagate from the cornice to the foundation at a distance of 4–6 m from the common edge. A similar picture, but already with heaving of the soil, causes the identical propagation of two cracks, but only in the direction from the foundation to the roof.

If there is reinforcement in the base, it is quite easy to determine the defects of the bearing layer. The mesh will break approximately along the crack line in the supporting layer, and internal damage is clearly visible from the outside. If the base has not been reinforced, the finish can peel off in layers, while the crack in the load-bearing layer will be closed with solid fragments of the outer layer – on the surface of the facade, cracks appear in the vicinity of the base destruction line.

There are two ways out of the situation: if the foundation is intact, drain the site and let the building shrink for 1–2 years. If the foundation is damaged, it is subject to general or local repair and strengthening. To establish the fact that cracks in concrete are opening, it is necessary to excavate part of the foundation. Note in addition that most often the foundation is damaged precisely because of frost heaving: if in the area of ​​the basement the crack width exceeds 15–20 mm, then the foundation is, for sure, destroyed.

Types of damage and adequate methods for their elimination

It’s unpleasant, but true: most of the damage to the finishing layer flows from the inside to the outside: by the time the cracks and swellings become visible to the naked eye, the inner layers finally become unusable. This happens often, but not always, in any case, you should disassemble a section of the wall before proceeding with further actions..

It is easy enough to assume that the assessment of wall damage is carried out by the number of destroyed layers and their condition. In total, there are three cases of plaster flaking, the simplest of which is when only the outer decorative coating leaves, for example, a bark beetle or a fur coat. In these cases, removing the destroyed finish is the only correct solution. Neither fracture preparation nor fragmentary repair of large blisters will provide long-term results. If the entire wall was finished using the same technology, the appearance of similar defects in other places is only a matter of time.

If, after opening the decorative layer, it turned out that there are cracks in the base, the latter must be repaired. The depth of the restoration can vary. If the reinforcement is intact, the cracks are cut without damaging the mesh and filled, and the base thickness is increased. If the mesh is torn, deeper repairs are required, while the upper reinforcing layer is applied with additional reinforcement.

Peeling the base is also a fairly common type of damage to the facade finish. Basically, such a defect is typical for wet facades applied to insulation made of expanded polystyrene, which stood for several months under the influence of air erosion and sunlight. There is nothing to be done here: all the plaster must be dismantled, followed by an increase in the adhesion of the walls (sanding the PPP) and strengthening the base, a new base and a new finishing layer. It is very important to check whether the calculation of heat transfer and moisture accumulation is correct, whether the materials are of high quality and whether they correspond to the application. Quite often, developers decide to use an alternative look or finish..

Repair of the base reinforcement layer

If the mesh is damaged, the base sections are beaten off at a distance of 30–40 cm on both sides of the crack. In this case, the smallest and weakest fragments of the coating finally peel off. At this stage, it is important to check how reliable the adhesion of the remaining trim areas to the base is. Areas unaffected by damage can be left by sanding the edges to cancel out with a strip of about 15-20 cm.

The restoration of the facade implies a fragmentary or complete reapplication of the base. Moreover, the new mesh should be laid with an overlap of 20–30 cm on the areas where the old one is preserved. Such patches are made according to the main technology of applying facade plaster: first, the entire open surface of the insulation and adjacent areas of the preserved base is wiped with a mixture, then the mesh is applied and smoothed, at the end a thin leveling layer is applied. After repair, the wall must be allowed to dry and reinforced with additional disc dowels if necessary. After that, the entire surface is primed and fastened with another base layer, usually with additional reinforcement..

In the absence of damage to the mesh, repairing the base is incomparably easier. The edges of cracks must be carefully cleaned with an abrasive trowel and primed well. It is important that the embedding is carried out with a compound of the same type with which the base is made. After repairing cracks, the entire surface of the base is primed until the absorption stops and covered with one general leveling layer about 3 mm thick.

Elimination of destruction of the decorative layer

The appearance of blisters on the decorative coating most often occurs due to the accumulation of moisture under it. Most often this happens due to insufficient vapor permeability of the selected type of plaster. The consequence of this may be the formation of a crumbling layer on the surface of the base that has undergone water and frost erosion. In such situations, it is better to reconsider your decision regarding the choice of finishing materials..

One of the exceptions is the detection of a defect after 3-4 years of facade operation. This manifests itself in the form of swellings, visible only when looking close to the plane of the wall. Usually there are very few such defects, in these places the priming technology or the exposure period in the open air is simply violated. In such options, you can carefully make holes in the upper part of the blisters, pour a low viscosity sealant into the cavities and roll the bumps with a roller, pressing the exfoliated fragments to the base.

If the delaminated areas are extensive (more than 1-1.5 m²), the best way to repair is to dismantle the destroyed finishing layer and apply a new composition over the entire plane. Let us remind once again that this approach is possible if two conditions are met: the reinforcement and the base itself are not disturbed, and the connection between it and the preparatory (leveling) finishing layer is beyond doubt. At the same time, the repair is not performed fragmentarily: the exfoliated areas are removed completely, and the upper decorative mask is simply removed from the surviving ones. After that, the entire plane of the wall is primed and covered with a leveling layer, on which, after drying, a new decorative coating is applied.

Will surface strengthening help?

You can often come across the opinion that to restore the appearance of the facade, it is simply enough to cover it again with a decorative composition, but this is only a temporary solution. Due to the formation of an air gap between deeper layers, such actions will only aggravate the situation, moreover, it is impossible to predict in advance how an increase in the thickness of the protective and decorative layer will affect the vapor permeability of the wall as a whole..

Even with the application of a new base over the facade and attempts to save money on dismantling the coating, the repair will not give the expected result. Yes, a new, tough crust will form on top of the finish, which may well be able to withstand the overall weight of the finish and the pull-off force for some time. However, all external finishing layers must comply with the rule of increasing hygroscopicity from internal to external, which is absolutely impossible when performing double plastering. It should be remembered that only the aesthetic service life of plaster facades is at least 10 years, after which the building is simply painted again. The mechanical durability of the “wet” facade is at least 30 years, so a consistent and thoughtful approach to the problem of destruction of the finish, as a rule, turns out to be more economically feasible than taking temporary measures.