If you are looking to re-render a wall then EWI Store can provide all the materials. The process is relatively simple, but the finish should be long lasting and certainly improve the look of the existing façade.
Do you need to remove the existing render?
To re-render a wall, the first thing you must do is check the quality of the existing render. If in any doubt about its strength, then it must be removed before applying the new render coat. This is a painful but necessary process, since the new render needs to be installed on a stable substrate. If it is not removed prior to installing the new render, then sometime down the line cracks may appear or worse, your new coat of render will fall away from the wall.
If the existing render is okay in patches, then you have a choice – you can either remove the existing render so you are left with the bare wall or you can using a wall levelling compound to where the old render has come away from the wall. The wall levelling compound we provide can fill gaps of up to 50mm, so this can be used to build up to the thickness of the good render to give you a stable surface on which to apply the new render.
Following either of the methods above will give you a suitable surface on which to re-render. Once you have a strong, stable surface, the next thing to do is install the reinforcement layer. Using a notched trowel, you need to add a 6mm layer of EWI-220 Adhesive to the wall. Each 25kg bag of EWI-220 (once mixed with water to form the adhesive putty) should cover approximately 5m2 when 6mm thick is applied.
Reinforcing the reinforcement layer (or basecoat!)
Once applied, you then need to embed the fibreglass reinforcement mesh (EWI-640). This comes in rolls – 50m long by 1m wide. We recommend doing this in vertical stripes, and each stripe needs to overlap the last by 100mm. The easiest way to embed the mesh is to first cut a strip the length of the wall top to bottom then, starting at the top, gently push the mesh into the adhesive, so it stays in place. Once the mesh has been gently pushed in by hand, turn the notched trowel around so you are using the flat edge and drive this down from the top – this will draw adhesive through the holes in the mesh and embed it within the adhesive layer.
The aim is to get the mesh embedded within the middle of the adhesive layer – the mesh is really important as it provides strength and flexibility to the render system, ensuring it won’t crack.
Once you have embedded the mesh, stand back and admire your handiwork. If it is not completely flat, we recommend using a wet adhesive mix to smooth out the surface. Do this before the underlying adhesive has fully gone off to ensure it adheres properly. It is very important the reinforcement layer is flat prior to applying the render because the render layer is very flat.
Once you are happy with the reinforcement layer it is time to prepare the wall for the final render topcoat. The key to a nice finish when rendering is applying the render very thinly – if the render is 1.5mm, then the render layer should be 1.5mm in total. Likewise if the render finish is 1mm (size of aggregate in the render) then the render layer should be just 1mm in total.
The first thing to do prior to applying the render is to prime the wall first. If you are using a colour render finish, then normally the primer will need to be tinted as well – check that this is the case before starting the render work.
One 21kg bucket of primer will cover approximately 70m2 of wall, while the small 7kg bucket will do just over 20m2. The primer can be applied with either a brush or a roller and this needs to go off before applying the final top coat of render. It is important to match the primer type (e.g. acrylic or silicone) to the final render you are using.
Picking the render
We offer several different types of render including water based renders (acrylic, silicone silicate and silicone) as well as mineral render which is concrete-based.
The water based renders come ready mixed and tinted as per the colour selection. The mineral render is a grey colour and needs to be painted once it has been applied to the wall. We have discussed the major differences between the renders previously and you can read more about that by clicking on the link below
Applying the render
The render is applied using a trowel as usual; ensure you take off any excess though, as the render layer is incredibly thin. Once the render is on the wall, the final finish is achieved using a plastic float.