If you have a wall with damaged cement render, you may be wondering how to repair it. In this article, we'll explain how to remove old, damaged render and prepare the surface for a new rendering. We'll also show you how to mix and apply a new render to the damaged area for a complete, long-lasting finish. Plastering is very similar to rendering in that plaster is mixed to a certain consistency and then applied to a wall surface in two layers.
However, unlike plastering, the thin plaster layer is applied first and then the thicker finish coat is applied afterwards. If you have a traditional Tyrolean render finish, the damaged render may be a previously repaired patch. The contractor or person who originally repaired the damage may not have used enough cement in the mix, which is why it looks like sand. To begin repairing the render, use a hammer and chisel to crop it outwards from any obvious damaged area until you find the edges of any solid and sound rendering.
Damaged or burned renderings will sound hollow when hit, so tapping with the hammer can help identify these areas quickly and easily. Keep working until all the damaged and defective rendering has been removed from the wall. Using a small hammer with an angled (slightly angled) chisel is the best tool for removing rendering over a large area as it saves time and energy. The chisel's cracked angle makes it easy to get the plaster out of the wall without digging into it.
Once all the old and damaged plaster has been removed from the wall, go through all the edges of the plaster with your breaker and chisel and remove them so that they are 100% sound. Run along the edges to check for traces of damaged plaster. Once the wall surface has been thoroughly cleaned, apply an SBR base to the wall. This will help the first layer of plaster adhere to the wall surface and will also prevent the dry wall from absorbing all the moisture from the plaster before it has cured.
Use an old masonry brush to apply a layer over the entire area from which you removed the render. Make sure to also completely cover the bare edges of the existing render by painting SBR over them. Once the wall has been completely covered with SBR and cured, fill in any deep holes or depressions with plaster. When applying your first coat of plaster to the wall, make sure it lies on as flat a surface as possible so that you achieve a nice uniform 5-6mm finish on the wall. If it has a uniform thickness, it will cure at the same speed over its entire surface. The rendering mixture is then applied to the surface of the walls using a plasterer trowel and falcon, in the same manner as plaster is applied.
The falcon is loaded and then spread onto the pallet from there. As you apply the render mixture to the wall, push it toward it so that it adheres and then spread it out evenly to a thickness of 5-6mm. Make sure to force it onto any existing render edges for a good bond. Work your way along until all of your walls are completely covered with render. Applying rendering in a straight run on a wall can be tricky if it's your first attempt but nothing that can't be achieved with some time and practice.
If you're dealing with corners too, take your time and build them slowly - putting them too deep causes them to fall off. Once set, use your trowel to start forming your corner. Once your first coat is on your wall, let it dry until it's slightly damp before applying your second coat - if it dries too much before applying your top coat, all of its moisture will be absorbed before it dries properly. Unlike plastering where you apply your thick layer first followed by your thinnest top layer later, when rendering you apply your thin layer first followed by your thick layer later. When applying your second coat of render make sure you use enough pressure so that it adheres properly but not too much as this can cause cracking. Once both coats are dry, use a polyurethane float with 5-6 screws inserted at one end to form a scrape layer on top of your coating layer. This will give you an even finish on your walls that will last for years.
