Renders come in many different types and some of the more recent acrylic and other modern renders are manufactured. For someone who wants to know how to make a render, they will find themselves bewildered and overwhelmed by the large amount of articles and websites containing information about the cement mortar and lime renderings. It must be mentioned that this vast amount of information available to people who want to know more about rendering applied specifically to cement and lime renderings and not to the recently developed renders with additives that give them distinctive characteristics e.g. polymer additives in the render allows the render to be applied to be applied as a single coat. There is much discrepancy on what the ideal ratio of one product to another should be when it comes to rendering. One suggestion would be to use a straight lime mix that is applied on exterior walls. An alternative suggestion by some professionals would be that lime should generally be mixed with a certain kind of sand and that the mix should contain one part lime to three parts sand. If a cement render is required, then the render mix would contain cement, lime and sand.
Choosing the Right Render
Choosing the right render is a complex decision to make because the type of suitable render to be chosen depends on the type of walls to be rendered as well as what the typical weather conditions might be in that area. For people who are not rushed to completing the rendering of their property, soft lime renders are to be advised as they and can take a while to harden. However, if you have a tight time frame to complete your rendering project, it would be advisable to add some cement to the lime render to make the lime render harden more quickly. Note: Adding excess cement to the lime render has to be avoided because this would cause the render to harden quickly, increasing the likelihood of it cracking.
Types of Render Mixes
In this section, the different types of render mixtures will be mentioned here as well as the method to which they are achieved.
- Render mixture that produces a smooth finish. In order to achieve this, you need to apply a rough coat to remove any unevenness in the walls and then apply two coats of lime render afterwards. Note 1: Coarse sand is mixed with lime to achieve a smoother finish. Note 2: Lime putty (calcium hydroxide, (Ca(OH)2)) that is at least three months old is required so that it is thoroughly slaked and less likely to result in cracks in the render.
- Render mixes with waterproof properties can be created by including a waterproofing material such as Celtec mixed with two parts cement, 3.5 parts of sharp sand and 3.5 parts of builder’s sand. It is important to get the mix right, particularly if you want a cement render, a mix of clean sand, cement and lime.
- Render mixes with a textured look can be achieved by varying the tools you use on the final render coat such as using a mix of trowel, brush and sponge.
- Render mixture with enhanced water resistance is achieved when you add a hydrophobic (“water hating”) polymer additive to the render mix.
Ready Mixed Renders
Alternatively, if you are still unsure what render mixture you require to make, ready mixed renders are available on the market for you to purchase.
Premixed acrylic renders are versatile as they can be used on a wide range of buildings and on interior and exterior walls. The advantages of using acrylic renders are that they ideal for properties located in an area where the weather is known to bad because the acrylic renders are among the most water resistant renders. Note: some acrylic renders will need to have extra cement added shortly before the mix is applied to the walls. Another advantage of premixed acrylic renders is that the render dries out in a couple of days instead of several weeks.