The reason people have this misconception is because of the idea that the weather has to be warm in order to render a property. Despite what people think, rendering can be done all year round, however, there are still a few factors which will affect whether or not the rendering can be done any time of the year.
The first factor is that the weather has to be dry. This means that’s rendering cannot be done when it is raining.
The second factor is that the weather cannot be too cold. This means that during the winter months, the temperature can’t be at a temperature where there is a risk of fog.
Although the rendering can be done all year round, it does become difficult in the winter months to find the right time to render.
Any plasterer can do the job
This misconception can cost a client thousands of pounds. The idea behind this is that rendering and plastering are very similar and therefore, people assume that they can both be done by a plasterer. The problem is that rendering is more complex and requires a bigger skill set.
Plaster is a simple sand and cement mixture and the system is very simple – it only requires the plaster. A rendering system has to be a lot stronger and therefore, the system is more complex. A modern system, for example, may require a basecoat, beading, reinforcement mesh and a top coat.
A renderer requires more skills than a plaster to do his/her job. Not only is the systems more complex but there are some many different render systems (From spray on renders to hand applied renders).
Rendering over paint is fine
People want to save money, so they assume that they can render over a painted wall without removing the paint first and expect to do so with no issues.
However, this is not correct. Rendering over paint will create a weak interface which is not suitable to render over. This is because any movement or the impact of any object may cause the render to fall away from the wall due to a weak bond.
Also, organic growth will affect rendering over paint. Although it may have been brushed off, it can remain in the pours of the substrate. When this happens, delamination can occur. Delamination is the separation of layers which also means a weak bond between render and substrate.
All rendering systems are the same
There are a wide range of render systems. Each one has its own characteristics and properties.
Usually applied as a thin coat finish
Brings colour and texture
Silicone is used to give it a longer life and the ability to ‘self-clean’
Applied in 2-3 coats
It’s cheap on labour but expensive on materials
Has the tendency to crack with structural movement
Requires frequent painting in order to make it look good
Based on either white cement or lime
Has polymers and other plastic based products to make it less likely to crack
Scraped Texture / Monocouche render
Can be applied by hand or spray
Use of additives make them more flexible and less likely to crack
They can be ‘self-cleaned’
They use white cement and are self-coloured meaning you can have a decorative layer as well as waterproof layer