What are the different types of render?
The type of external render
The type of external render we use depends not only on the technology of house wall construction. It should also depend on the environment in which the house is situated. On the elevation of a building situated around trees or in a seaside area, a different render will be suitable than on the exterior walls of a house built next to a busy road. Also, significant is the exposure to sunlight or shade of its walls. If you are applying a thin coat render, the type of external wall insulation material used may also affect the decision on its selection, e.g. acrylic render is not recommended for walls insulated with mineral wool.
Types of external thick coat render
Traditional render is also referred to as thick layer render because it is 2-3 cm thick. These types of rendering are relatively inexpensive and are designed for finishing all concrete and brick walls. Such external renders are divided into two main groups – cement-lime and cement renders. They can be smooth or with a decorative texture, e.g. lambda, or less popular – socket and imposed house rendering.
Cement-lime rendering services are very popular, mainly because of their low price and easy availability. They are also characterized by high vapor-permeability and durability. Their disadvantage is that they absorb water well and are not resistant to shrinkage, which may lead to cracking of the render during setting. When laid, cement-lime rendering projects have a slightly rough texture. Such traditional renders are more watertight than cement-lime plasters and resistant to mechanical damage, but they are more difficult to apply. Cement render finish binds and hardens quickly – if not applied correctly it can crack in places.
Types of thin coat renders
Thin layer plasters are characterized by richer colours and a greater variety of textures than traditional cement render system. Their advantage is also versatility – they can be used not only to finish two-layer walls, but also the walls previously plastered with traditional thick-layer plaster. They are also used on even surfaces of walls made of, for instance, concrete blocks. However, you need to pay more for such a rendering system. On the market, you can find the following thin layer renders – mineral, acrylic, acrylic-silicone, silicone, silicate, and silicate-silicone.
Mineral render – popular thin coat renders
Mineral renders belong to very durable and weather-resistant types of exterior render. They contain cement and polymers that improve adhesion. They are also characterized by good vapor permeability. Furthermore, they are available in quite a limited number of colours – usually in delicate pastel shades. This is why they are often painted with a vapor-permeable paint. Mineral plasters unfortunately absorb rain water and can therefore become dirty quickly.
Acrylic render – durable thin coat renders
Acrylic modern renders are the most flexible of the thin layer renders (and therefore the least prone to cracking) and easy for applying render (also at low temperature). They are available in many colours and can have strong, saturated colours that do not fade. Their advantage is also a wide range of textures – apart from smooth, they can have lamb or woodworm structures. Acrylic type of render are also characterised by relatively low water absorption and vapour permeability, which is why they are perfect for walls insulated with foamed polystyrene. It is worth choosing acrylic renders with the addition of biocide agents – fungi and molds will not appear on them.
Silicone render – self-cleaning type of render for demanding customers
Silicone renders are a type of exterior plaster of excellent quality. They combine the advantages of mineral, silicate, and acrylic render. Silicone resins are their binder. They are distinguished by low water absorption and hydrophobic properties, thanks to which water does not soak into the silicone render surface but flows down it. However, it does not reduce its very good vapor-permeability. They are also distinguished by resistance to dirt absorption and elasticity, which makes them suitable for application even at low temperatures. They retain their intensive colour for many years.
In this type of polymer render, the binder is potassium water glass with the addition of plasticizers. Silicate renders permeate water vapor well and at the same time is not susceptible to moisture and destructive atmospheric conditions such as heavy rains. They are also resistant to the attack of mold or other microorganisms. They are flexible, that is why it is worth using them in places where small cracks appear, which can be observed in traditional types of render. Their advantages also include durability and resistance to environmental pollution. They can be tinted in many colours – most often bright ones.