Rubbing types - Which plaster for outside and inside?

• Rubbing - types
  • Plaster for exterior
  • Cleaning mortar for interior
• The right composition
  • exterior plaster
  • Innenputz

Rubbing is not always rubbing - depending on the application you need different types of plaster - whether silicate, synthetic resin or clay plaster. We clarify which plaster you should use for outside and inside.

Rubbing - types

Whether outside or inside, you first need the right plaster for the given plaster surface. In addition, the plaster can still help fulfill some special tasks. In detail, you should decide on the advice of a specialist dealer, here is a brief overview of the choices:

• Plaster mortar: building material for the production of plaster
• Starting materials: binders, aggregates and additives
• Are mixed by the manufacturer to dry mortar
• The manufacturer determines the amount of water to be mixed
• Mixing takes place in mixing machines on the construction site
• Dry blends for exterior plaster usually contain dyes that make painting unnecessary

Plaster for exterior

If you inform yourself about plaster, you will often find yourself subdivided into plaster groups according to DIN V 18550, while on the other hand you are told that the DIN V 18550 no longer applies. Both are correct, the DIN V 18550 was already completely replaced in June 2015 by DIN 18550 1 (outside) and 2 (inside). But literature and product descriptions are often much older (and are simply taken over in more depreciated than researched articles), and seasoned construction practitioners are alluding to experience and situation anyway.

These are the plaster mortar groups of the old DIN V 18550, subdivided according to material, together with the suitable subfloors:

• PI lime mortar, of which P Ib as exterior plaster with low stress
• PII lime cement mortar, as external plaster with water-resistant properties and increased strength
• PIII cement mortar, as external plaster in the area of ​​the basement outer wall and for the outer base area
• (PIV, V only interior plasters)

In DIN V 18550 it is also to be read in table 2 which mortar group is suitable for which application outside:

• without special requirement
• water resistant
• water repellent
• basement wall exterior plaster
• Exterior socket plaster

These designations sometimes come together with the division of DIN EN 998-1, valid since 2010, the exterior plaster according to properties / intended use in:

• GP standard plaster
• LW light plaster mortar
• CR rendering plaster
• OC plaster plaster for exterior use
• R rendering plaster
• T distinguishes between thermal insulation render mortar.

Cleaning mortar for interior

With regard to the classification, the above applies to external plaster, probably more often than the designations according to the current DIN 18550 1 you will encounter a plaster of mortar designation according to the old DIN V 18550.

For interior plaster, there are the following plaster mortar groups and subgroups:

• PI lime mortar, of which P Ia as interior plaster with low stress and P Ic as interior plaster for rooms with normal use including damp rooms
• PII lime cement mortar, as interior plaster with increased abrasion resistance also for damp rooms
• (PIII only outside plaster)
• PIV, V gypsum mortar, P IVa, b, c, V as interior plaster with increased abrasion resistance for normal use; P IVd interior plaster with low stress

For interior plaster, DIN EN 13279 also specifies plaster mortar groups:

• A: Different types of plaster binders, eg. B. for gypsum wallboard
• B1: gypsum plaster dry mortar
• B2: gypsum based dry mortar
• B3: gypsum lime dry mortar
• B4: plaster light dry mortar
• B5: Gypsum-containing light-weight dry mortar
• B6 gypsum lime easy-to-clean dry mortar
• B7: gypsum dry mortar for plaster with increased surface hardness
• C: gypsum dry mortar for special purposes, eg. B. acoustics, thermal insulation, fire protection

The main binders and their proportions as well as the proportions of other ingredients are determined for the individual types of plaster, more additives and admixtures may be added by the manufacturer.

In DIN V 18550 it can be further read in Table 3 which mortar group is suitable for which application:

• Interior plasters for normal use
• Interior plasters for damp rooms

This classification of DIN EN 998-1 in standard plaster GP, light plaster mortar LW, crimp mortar CR, plaster of exterior plaster for exterior OC, rendering mortar R and thermal insulation mortar T also applies to interior plaster.

The right composition

When you have found your plaster group, another decision is made: The composition of the plaster.

exterior plaster

Outside, it's all about whether you want to use synthetic resin plaster, pure mineral plaster or a compromise between the two:

a) Synthetic plasters were until recently the most widely used plasters, especially as top coat they are very easy to use. As a binder, a polymer dispersion is used as in synthetic resin paints (stable dispersion of polymer particles in an aqueous phase), the resin is thus finely dispersed in water in the emulsion paint or the dispersion plaster. The supplements can be mineral or organic.

Synthetic plasters are considered to be particularly resistant and are therefore often used in outdoor areas, but professionally applied mineral plaster is just as resistant. Synthetic resin plaster has other advantages over mineral plaster: It is (depending on the resin more or less) elastic and therefore adapts to deformations of the substrate z. B. by heat and moisture better than mineral plaster.

Beginners will therefore often come to synthetic resin plaster, because even when (uneven) order in too hot / too cold / too dry / too humid environment hardly produces cleaning cracks and also adheres well to a variety of (even poorly prepared) substrates.

In addition, they can be applied much thinner than mineral plaster, therefore harden faster and can take some mechanical stress better than the rigid mineral layer due to the elasticity. But not many, some of the challenges of modern times set synthetic resin plaster to the same extent as mineral plaster:

The (alleged) advantages, however, are faced with significant disadvantages: synthetic resin plaster is water-repellent and also absorbs no water vapor. So you surround your house with a waterproof layer, which is also on strongly weathered facades (which are rare and which must be protected by shuttering / roof overhang) against producers recommendation is not advantageous: If moisture is not intercepted by the material, it lies on the Surface on, which dries so slowly to never, damage will not wait long after the first hairline crack.

Algae and fungal spores are applied with moisture, and synthetic resin plaster is susceptible to algae and fungus. The manufacturers know that is why fungicides and algicides are often in the plaster - whose active ingredients you should inform yourself (safety data sheet, individual ingredients look up), namely the poison lands after every rain in the front yard, where the children play (and in the channel system / the treatment plant / groundwater).

Less dense and less contaminated with toxic additives are the new silicone resin plasters that combine silicone resin emulsion and polymer dispersion in the binder. To what extent this is true, would have to be explored for the individual product.
Synthetic resin plaster is standardized in the framework of DIN 18 558 Part 1 in the plastering systems, P Org 1 performs as exterior and interior plaster suitable synthetic resin plaster, P Org 2 only suitable as interior plaster synthetic resin plaster. "Org" stands for the polymer dispersion, the organic binder of synthetic resin plasters, which is composed of carbon compounds.

b) Mineral plasters are made with inorganic binders of mineral origin. Minerals are the natural substances that make up the rocks of our earth, so with mineral plaster you are cleaning "stone on the wall". The most commonly used binders are lime and cement (from various minerals such as lime, quartzite, some clay and iron ore).

Mineral plasters have great advantages: they are permeable, they can absorb moisture and release it without being damaged. Therefore, they never remain permanently moist, mold and algae find on mineral plaster neither enough moisture to live, nor food in the inorganic material, and the alkaline pH acts naturally naturally fungicidal.

Reiner Zementputz forms a very hard and durable surface, but is more susceptible to cracks than synthetic resin plaster, because it can not cushion tensions in the substrate so well. Less brittle is lime cement plaster, which is often used outdoors. Lime cement plaster and pure lime plaster were of course used until the early 1980s, then came the era of synthetic resin plaster. Mineral plasters bind relatively slowly, but because of their outstanding home-hygienic properties are just becoming increasingly important again. You can find out more about pure lime exterior plaster for timber framing or timber frame construction here: www.fachwerk.de/fachwerkhaus/wissen/putz-zement-40212.html.

c) Compromise solutions are mixtures of mineral and synthetic resin plaster such as silicate plaster . It consists of potash waterglass with synthetic resin dispersion and is depending on the composition more dense synthetic resin plaster or more permeable to water vapor.

d) plaster systems z. For example, used in ETICS (thermal insulation composite system) and consist of two coordinated plaster layers of flush and surface plaster. The flush can also be a synthetic resin plaster, in practice, the triumphal process of synthetic resin plaster was limited to the top coat, while as sub-plasters continued mineral plasters were used, because the better on the plaster base (the masonry) adhere.
If you want to use a plastering system because it belongs to your planned ETICS, you might be interested in the following view of a critical mind: www.konrad-fischer-info.de/2134bau.htm, with a comprehensive selection of literature at the bottom of the page,

Innenputz

On the inside, too, you must always decide between synthetic resin plaster and diffusion-permeable mineral plaster, with basically the same arguments for one or the other type of plaster. But in the living area even more speaks for the use of diffusion-open natural material:

• Moisture-compensating wall covering improves the living climate by regulating the humidity
• Exciting selection of base material: gypsum, loam, lime, mineral-finished plaster,
• Each material has its own advantages
• Material blends offer further possibilities

Which of these plasters can be processed to which type of rubbing depends on the consistency of the individual plaster mixture. If you look in this direction, there is still a lot to discover: for large surfaces, modern lime plaster of the mortar group P Ic, which can be applied by machine and single layer and offer completely new possibilities of rubbing patterns. Clay plasters with colored surfaces that are rubbed after adding straw fibers or mother of pearl; Magnetic plaster as intermediate plaster, with which you plaster oversized pin boards; elastic brick floor plasters, natural fiber plasters and textile plasters, which enable completely new wall coatings and designs as a rubbing plaster.

Would you like to know exactly how to process rubbing compound "> Apply rubbing compound