If you’re considering rendering the exterior of your home then the choice of options can be bewildering. House render has come a long way since the old days of peddle dash (Sand and Cement), thanks to new techniques and technologies you can now choose from a wide range of finishes.
It’s important to know the difference between monocouche render, silicone render and acrylic paints so we lift the lid to guide you through the main external render finish types.So how do you choose which materials and products are the best for your home? The best place to start is by asking why you’re considering rendering your property.
Do you want to weather-proof the exterior or repair damaged brickwork? Do you want to improve the overall appearance of your home, giving it a fresh new look, or perhaps you want to save yourself the effort of having to clean/repaint your brickwork every few years?
You should also consider the pros and cons of each type of render, as each has different properties that suit different needs.
What is render?
Renders are made up of component parts in varying amounts - the combination of which determines the properties and characteristics of each type.
- Binding agents are the adhesive element, holding the render together and giving it strength. This is typically a cement, lime, clay or gypsum base.
- Structural fillers provide the volume or bulk of the plaster and this would typically be sand.
- Water binds the components and ‘works’ the mixture together.
- Fibres can be added to the render to provide extra strength as well as stretch. Traditionally these would have been horse hair, hemp or straw fibres but now are more likely to be made up of fibreglass, nylon (plastic) mesh or steel fibres.
- Additives, or chemicals that alter the characteristics of the render, such as silicon and acrylics to add further elasticity, durability and colour finishes.
There are five main types of render for you to choose from and we’ve summarised each of these, so you can consider which type might be best for your next project;
Lime render has been traditionally applied to walls built out of low quality stone or rubble, or where walls are exposed to driving wind and rain. The lime render does not create a barrier for the moisture but acts like a sponge and absorbs the water, stopping it passing through the wall by sucking it up. The moisture then evaporates from the lime render into the outside air when the rain dries up.
Lime render is seen as an eco-friendly product as the curing process absorbs CO2 from the air as the render ‘sets’ to a limestone state. It’s also possible to colour lime render in a wide variety of colours and shades too. This type of render however requires a highly skilled application and can be expensive.
Sand and Cement
These renders are typically much stronger and harder than any lime render and are often painted.
Cement renders are not suitable for older buildings as any movement can quickly cause cracking in the render. Additives can be used in the cement to increase the flexibility and durability but because this type of render is so hard it will always be prone to cracking.
Cement renders are not waterproof so they are generally finished with a finishing coat, such as paint, for protective and decorative purposes. Sand and cement render is not suitable below the damp course and can be higher maintenance in the long run due to its painted finish. However, the huge advantage that sand and cement render has is that it is strong, cheap and relatively easy to apply.
Acrylic Render Coating
Render can be applied as either thin coat or thick coat and the options we’ve covered so far (Lime/Sand and Cement) are both examples of a thick coat covering.
Thin coat house renders are applied in an extremely thin layer over the top of a specially engineered basecoat. The external walls of your home expand and shrink during cold temperatures and hot temperatures. Whilst this is only a tiny amount, if the house render isn’t flexible enough you can expect to see a certain amount of cracking over time. When you use a thin coat render, you are guaranteeing flexibility because it hasn’t been applied in a solid, thick layer.
The basecoat underneath the render would have a fibreglass mesh embedded within it. Fibreglass mesh is really flexible so as your house expands and contracts it will hold the basecoat together and prevent cracking of the thin coat render.
Acrylic is the cheapest type of thin render and comes in a range really vibrant colours. It is also the most impact resistant which means that it is extremely strong – this is particularly good if you have kids who are keen on kicking footballs against the wall! However, the main drawback is that due to its overall strength, you’re sacrificing the ‘breathability’ aspect which can be an issue for some properties.
The French term monocouche is a modern render system which translates as ‘one coat’ and distinguishes itself from other traditional one coat renders such as sand and cement with the inclusion of additives.
Monocouche render provides a low maintenance, weather resistant, hard wearing and flexible coating to the exterior of your home, as well as an attractive finish thanks to the house rendering colour pigmentation right throughout the mix, meaning no additional building painting.
The main disadvantage of monocouche is the material cost, however it is important to note though that monocouche render systems will save you on labour costs and maintenance in the long term there is no need for sealing or re-painting. It is also prone to cracking as it doesn’t flex with the natural movement of your walls.
Silicon Render Coating
Silicon or Silicone render (spelt with or without the ‘e’) is another example of a thin coat finish, with all of the strength advantages of acrylic render, but which offers unsurpassed breathability and vapour permeability, i.e. it will allow water vapour to escape through it, thereby preventing damp.
Once installed on the wall silicone render is hydrophobic, which basically means that it repels water and therefore can be considered self-cleaning in that rain water will simply run off it – it’s an ideal render to choose if your home is situated in an area where there are lots of trees and plant life.
Silicone render can be applied extremely thinly (6-8 mm) on the wall so the advantage of this is that it is extremely flexible. When the house moves, the render moves with it. It is advised that this type of render should not be applied during the harsh winter months or when it is raining as the system does take a few days to cure – but once installed it should be maintenance-free for over 10 years, aside from the odd pressure wash from time to time to keep it looking nice and clean.
Because of it’s superior quality finish and long life-span Silicon render is our recommended approach. It provides you with a modern look, a non-cracking finish, is low maintenance, and lasts for many years.
If you are considering rendering your home and would like to speak to a member of our expert team, please get in touch today. We’re experienced in advising customers on the options available and have a great range of products available for you to choose from.
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