Choosing exterior wall finishes
When it comes to choosing products for your rendering project, there are many elements to consider. The look and quality of the finished work not only depends on the skill and technique of the applicator, but also on the material used.
When choosing render and texture for your project, consider the following:
With different types of decorative wall finishes, you can create an imitation of natural materials (e.g., marble) and other finishes, such as smooth concrete finish (i.e., micro cement). Usually the manufacturer indicates on the package what type of finish the mixture is.
At Render Supply Co we supply a range of cement- and acrylic-based renders, textures and other wall finishes.
Some render products have higher drying capability than others. Typically, render will be touch dry within 1-6 hours, depending on the product as well as environmental factors, such as temperature. However, render requires additional time to cure, which takes around 24-72 hours, depending on the product, environment and application, such as thickness. Care should be taken to protect the newly applied product from harsh weather conditions (rain, high wind, hail and extreme heat) for that duration. Once cured, application of the top coat is ready to apply (such as Iconic T28 or T66 pure marble texture).
The required thickness
Different render products can be used for different surfaces (e.g., cement sheet/blueboard, brick, blockwork, concrete and Hebel ACC panels). For example, some high build renders can be built up to 50mm and therefore are suited for use on rough surfaces, such as uneven brick walls or cavities and voids in block-work and concrete form-work.
The amount of render required to cover one sq. m. of the surface is taken into account when there is a choice between several options.
Bond strength (adhesion)
The higher the polymer content, the better render adheres to the substrate. There are also render glue additives that can be added to increase adhesion.
Compressive strength and flexibility
These characteristics refer to texture products, and determine the ability of the material to resist the appearance of cracks under the influence of loads and against the elements. High quality texture products, such as the Iconic range of textures, are more resistant to cracking. However, it is important to note poor preparation of your project, such as lack of waterproofing when it is necessary, can also result in cracks, no matter how high quality the texture is.
Texture comes in either a clear base or white base, and is then tinted to the colour of your choice. A clear base is used for darker colours, such as 'Momument' or 'Night Sky', whereas a white base is better suited for lighter colours. Texture can also be painted using a membrane-based paint, which can add extra protection and durability to the wall, or to simply change the colour of existing work.
And lastly, whether the mixture is designed for manual or machine application.
Types of render
The simplest type of render is cement-based, typically consisting of a mixture of cement, sand and a small number of additives. It is used mainly to level walls and create a base layer under decorative coatings but can also be used as a finish. For example, cement render can be applied as rough cast using a Tyrolean splatter gun.
The advantages of this type of render:
- High strength.
- Low price due to its simple composition.
- Plasticity can be increased by adding lime or plasticiser to the mortar.
The disadvantages of this type of render:
- Dries rapidly.
- Can be challenging to use as a beginner due to the crumbling nature of the product making it difficult to apply.
Produced on the basis of polymeric acrylic resins. Acrylic render of finishing mixtures is not highly resistant, but has many advantages:
- plasticity, no cracks
- good adhesion to mineral bases
- hydrophobization of the surface (repels water)
- ease of application
- a wide choice of colors
- service life up to 25 years
Disadvantages of acrylic render:
- Tendency to burn out
- Unsuitable for application on metal
- Attracts dust and gets dirty easily
Another important property is low vapor permeability. Therefore, acrylic render can not be applied to the facade of aerated concrete. It can lead to moisture accumulation in the pores and cracking of the walls.
The composition of mineral plaster mixes includes marble or quartz crumb. The advantages of mineral facade plaster:
- High vapor permeability
- Resistance to mold damage
- Frost- and fire-resistance
- Resistance to atmospheric precipitation
- Surface is easy to clean
- Ease of application
The disadvantage of mineral plaster mixes is the limited choice of color, but this can be corrected by painting plastered walls with paint. In general, it is a good choice for finishing outdoor walls.
Silicone render is based on silicone resins, which give self-levelling properties. The advantages of silicone render mixes are:
- Self-cleaning during rain
- High water vapor permeability
- Dust-repellent properties
- Water-resistant surface
- Well tinted
- High degree of adhesion to all bases on which it is applied
The high price of silicone render mixtures can determine the choice not in their favor.
Render is one of the most attractive and versatile ways of finishing exterior facades. A large selection of colors and finishes allows you to choose the right option for your project.
We hope that this article was useful to you. Leave your feedback and questions in the comments below. You can read more about decorative wall finishing on our blog.