Render is one of the most common exterior surfaces that homeowners want to paint, but with so many types of renderings, it can often be difficult to know exactly how to go about it. That is why we’ve put together our complete guide to painting furnishings that contains everything you need to know before you get started. 

A Guide To Render:

The exterior walls of properties can come in a wide range of forms, including natural brick, stone, or concrete. One of the most popular forms of external finish, especially in Melbourne, however, is external furnish. Render is a form of external wall plaster that is applied to the masonry of properties to provide added protection from weathering and to leave an attractive finish to the property.

Like all building materials, not all furnishings are made the same and can vary widely in terms of look, composition, and performance.

Conventional render : 

 Conventional render, often known as sand and cement render, is the most common form of render you will come across. It is a relatively inexpensive furnishing that can be applied easily, which is why it is a popular choice for furnish projects. On the negative side, a sand and cement mix is less advanced than other forms of render, as it can uptake moisture, has low breathability, and is rigid, which can cause cracking due to movement. Furthermore, sand and cement do not come pre-colored, meaning it is almost always painted to leave an attractive finish.

Silicone render : 

Silicone render is a more advanced form of render that has higher breathability than standard sand and cement render while also having water-repellent properties due to added silicone. This provides silicone furnishing with extremely high durability thanks to the fact it does not absorb or trap moisture within the render, which can lead to damage. While it comes pre-colored, some silicone furnishings can suffer from staining and discoloration over time, which can often lead to them being painted further down the line.

Acrylic render : 

Another newer form of rendering, acrylic furnishing, is less breathable than silicone furnishings. It is not water repellent, although it is more cost-effective and offers a pre-colored finish, unlike sand and cement render.

Lime render:  

Lime render is an established form of render that has been used for hundreds of years on older heritage properties. It is highly breathable, making it breathable, allowing it to help regulate moisture levels in these older properties. However, it does not offer much resistance to weathering due to its high level of porosity.

Pebbledash: 

Pebbledash is a very popular form of render that was popularised in the 1970s as a highly durable render system that provides excellent weather protection, which is why it is commonly used in coastal and rural areas. It involves applying a plaster to walls and then throwing various pebbles and stones to the surface. Roughcast is a similar form of furnishing, which also involves pebbles and stones. However, these are added to the render mix itself rather than applied to the outside of the wall. Pebbledash is not a pre-colored render and can leave a dated finish, which is why it is one of the most common forms of furnishing to be painted.

Can Render Cause Damp Problems?

Here in Australia, we are all too familiar with damp problems due to both the level of rainfall we get and the way many properties are constructed. Damp can come in a range of forms, including rising dampness, penetrating dampness, and condensation. All of these forms can occur on rendered walls if the right conditions are present, which is why understanding them and how they can develop is crucial.

Rising dampness is caused by an external source of moisture, where water from the ground is able to soak up through the bottom course of bricks and continues to rise the walls of a property. This is why properties have what is known as a damp proof course (DPC), which creates a barrier on the bottom level of the property to prevent the bridging of moisture. Unfortunately, if this DPC is not present, is failing, or is bridged by furnishing, rising dampness can develop through the wall, causing significant damage and highly saturated walls.

Penetrating dampness, much like rising dampness, is caused by an external source of moisture; however, it is caused by rainfall that soaks into the external walls of a property. Penetrating dampness is a universal problem that can affect any external wall that is not water-repellent, including brick, stone, concrete, and the majority of external renders. It can particularly be a problem for the furnishing that have poor breathability, such as pebbledash, as they can trap this moisture when it enters the furnishing and allow the wall to hold the dampness within the fabric of the building. When the moisture enters the external wall, it can soak straight through into internal walls, damaging plaster and paintwork and causing black mold.

Condensation is an internal source of moisture caused:

It is caused by a natural build-up of humidity from day-to-day living, such as washing machines, dryers, and cooking. If a property suffers from poor ventilation or has poor breathability, this condensation will continue to develop within the walls, leading to black mold and dampness. Like penetrating dampness, poor breathability of external walls, either from the render itself or a coating on the furnish, will exacerbate these problems.

Damp, highly saturated walls will not only cause problems like mold but can also be a precursor to heat loss. When exterior walls get wet, they transfer heat much quicker than dry walls.