Traditional Rendering

Rendering

It is essential to remove any dirt or grime from the wall. The most efficient way of doing this is hosing the area with a strong jet of water or pressure washer. If there is evidence of mould growth, use a fungicidal wash over the area before starting the repair. If the brickwork still looks shabby after cleaning off the surface, rendering could improve the appearance.

Rendering is a coating of sand and cement. A coating can also contain small stones or chippings, which is called roughcast. This can be a difficult job, best results often applied by an expert. However there is a mix available for the DIY enthusiast, known as Tyrolean rendering, which is a dry mix. Once applied to the surface, allow it to dry before applying a layer of masonry paint.

Condition of the render

Cracks
If a crack has occurred in the rendering, it could be due to a structural fault. If there are any cracks in the rendering they should be filled. Widen the crack with the point of a trowel or old screwdriver, as this will make a wider area for the filler to key to. Brush away any loose dust or render before applying exterior filler. Press it in well, pushing into the gaps.

'Blown' rendering
If you tap an area of render and it feels 'live', it will probably sound hollow. This means the render is no longer bonded to the wall behind. If it has blown, it appears to bulge and should be broken away carefully to remove all loose render. Brush away any loose dust and widen the area around the edge with the point of a trowel or old screwdriver to improve the bond before applying new render. Use a mortar mixture comprising of cement: building sand in the ratio 1: 4. Add a little PVA bonding agent to improve the bond with the surface behind. If the render still feels firm, it can be left, but needs to be checked on a regular basis, and replaced if there is deterioration in the surface bond.

If the patching is obvious and in a very public area, it may be worth considering painting the wall for an attractive alternative finish.