If you want to smarten up your home’s exterior, or cover up brickwork that has become worn and tatty with age, then rendering is the answer. It can be an expensive job to get done professionally, but if you have the tools, the time and the wherewithal, rendering is something you might want to consider tackling yourself.
Tools and materials
For a standard two-coat, cement based render you will need the following tools: a mixer, a trowel, a hawk, a wheelbarrow, a bucket and a shovel, plus scaffolding, ladders and safety equipment if you are going to be working at heights.
The materials you will need for this job are an undercoat and the render itself. The undercoat, or ‘scratch coat’, is made with sand and cement, and so is the topcoat, although this should be prepared in such a way as to make sure that it is finer and smoother to the touch – many people opt for a finer grain of sand in the topcoat than in the scratch coat. Follow the guidelines on the packaging for more accurate advice on mixing each of the coats.
It is important to make sure that the brickwork is free from loose material before you begin adding the rendering. Scrape away, or dust off, any loose chippings or organic growth. You need to make sure that the brickwork is not too smooth, however, as it needs a ‘key’ for the rendering to hold on to when it is applied. If you have very smooth brickwork, use a trowel to scratch lines into the surface of the brickwork, so that the rendering will be able to hold. Dampen the wall a little before you begin adding the first coat.
Applying the render
When the first coat has been mixed satisfactorily, load the hawk and use a trowel to apply it to the wall. Always start at the top and work your way down. Apply the render by pushing upwards, in a small arc, and keeping a firm pressure throughout.
How much you should apply in each coat depends on the type of render that you are using and the strength of the brickwork itself. A fairly common standard depth for the scratch coat is 10 mm. It’s not a good idea to try and put too much on in one coat, as there is a risk that the render will be too heavy and fall off the wall. Also, remember that each coat you apply needs to be slightly less thick than the previous coat, so if your first coat was 10 mm thick, then your second should be 6 mm. As the first coat begins to dry, make scratches in it with a trowel so that this coat too will have a key for the next coat to hold on to.
When you come to final coat, use a trowel to make it as smooth as possible. If you see any cracks begin to appear as the render dries, spray the surface with water and use your trowel to smooth them over.