Putzarmierungen: plaster reinforcement and plaster base

Plasters are extremely diverse and versatile. In addition, there are different plaster systems that primarily define the structure of a wall or facade plaster. Below you will find a detailed guide that discusses the construction of plaster reinforcements such as the plaster reinforcement and the plaster base, but also all other layer structures.

Distinctive options for cleaning

Even the first distinction between plaster types such as interior plaster and exterior plaster is extremely rough. Plasters are differentiated according to numerous aspects. Here are some of the important distinctions:

  • about the binder used
  • over used surcharges
  • Purpose of the plasters
  • technical processing of the plasters

Multilayer or single-layer plaster structure

Depending on the plaster used, the structure is single-layered or multi-layered. Which plaster is used depends on the substrate. This can be a uniformly highly absorbent or non-absorbent substrate as well as mixed masonry with different properties (for example, hollow bricks with concrete, bricks, natural stones, etc.).

The special plastering: ETICS facades

But also the thermal insulation composite system requires its own structure of the plaster system used. In particular, the plaster for ETICS has again brought the possible layer structure into focus. There is quite a confusion in home improvement, because in a Putzarmierung completely different cleaning systems can be meant. In particular, the ETICS systems with plaster reinforcements that have emerged in recent years have made the confusion perfect.

Possible layer structure for plastering

Therefore, we want to show in principle how the plaster can be applied. In principle, the order is possible in the same order (from the lowest to the highest layer of plaster):

  • Spritzbewurf
  • Bonding bridge or primer
  • Concealed (also plaster base)
  • Finishing plaster (also fine plaster)

In addition, the layer thicknesses vary from thick-layer plaster to thin-layer plaster.

The Spritzbewurf

The term "Spritzbewurf" is a bit misleading because it suggests that the plaster is thrown on the wall as a processing technique. It is not so. More meaningful would be the terms "preform" or "bonding agent". The plaster is thrown with a tassel or a trowel on the wall.

This ranges from occasionally relatively dense splashes (net-like) to a thin continuous layer. Of course, the procedure also depends on the substrate (for example, concrete, brick, mixed substrate made of different materials such as bricks and natural stone or brick and concrete). The Spritzbewurf ensures that the later applied plasterer adhere better.

The bonding bridge

If the Spritzbewurf is not suitable, a bonding layer is often used. In principle, it is an adhesive primer that has to match the plaster used (organic or mineral) as well as the substrate (from barely absorbent concrete to strongly absorbent brick).

The flush (plaster base)

The flush can have different tasks. Thereafter, the layer thickness varies accordingly from 1 to 5 cm, in special cases to 10 cm. It can be about preparing the ground evenly.

Be it gaps in the masonry or a non-uniform surface that is so pre-smoothed. But also as a plaster base, the flush is used, so that the actual surface or plaster clings. Depending on the substrate, different materials and plasters or mortar are used.

Traditionally, sub-plasters contain cement or / and lime, but also gypsum (inside). But there are special sub-plasters, which are then more of a reason for cleaning. Thus, in a mixed masonry often a corresponding plaster base is produced.

But even with ETICS must be applied a flush. This flush is often a reinforcing plaster or reinforcing mortar - but executed just as a primer. This is not to be confused with a Putzarmierung. In the course of the guide more.

The finishing coat

Since the top coat remains visible at least in the structure (often comes a coat of paint), it is often referred to as a fine plaster. The top coat is applied either as a thick-layer plaster or as a thin-layer plaster. Organic plasters are usually applied as a thin-layer plaster and mineral plasters as a thick-layer plaster.

Plaster reinforcement and plaster base

The plaster reinforcement

The plaster reinforcement is a reinforcement that is inserted into the mortar or plaster. Often it is a metal grid. But it can also consist of other materials such as plastic. The plaster reinforcement is not really embedded in the plaster or mortar. Rather, the surface is pressed into the mortar or plaster and then only smoothed.

The plaster base

The plaster base, however, may have a reinforcement that is embedded in the mortar or plaster. In most cases, a reinforcing fabric is used, which is applied after two thirds of the total layer thickness. Then a third layer of mortar or plaster is applied. With a total thickness of 15 mm, first 10 mm are plastered, then the tissue is inserted. Then the fabric is filled in with another 5 mm plaster or mortar.

Applications plaster base

The plaster base is used to create good conditions for the subsequent finishing coat on a certain surface. The typical field of application today is the ETICS facade. The already glued foam boards or EPS boards are coated with a plaster base made of a special reinforcing mortar reinforced with a glass fiber fabric.

The insulation boards heat up relatively strong, but also quickly release this heat. They also cool down very quickly. This means that there is a clear difference in the thermal load between plaster and ETICS boards. The corresponding plaster base with reinforcing mesh absorbs these stresses and distributes them. So it can not come to cracks by the thermal expansions and the deformability of the plates.

Applications Plaster Reinforcement

The plaster reinforcement, however, is mainly used when, for example, in a mixed masonry with Putzrissen is to be expected. However, design-related cracks due to movements in load-bearing structural parts can not be avoided. For this purpose, the respective expansion and connection joints must be maintained.

Tips & Tricks

A detailed instruction on how to process the reinforcement fabric can be found here.

Product Image: Dmitry Kalinovsky / Shutterstock

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