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 a 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.
Pebbledash
If small stones or chippings are thrown onto the sand and cement mix already applied to the
wall surface, the finish is known as a peppledash surface. Pebbledash is a popular surface
coat, consisting of a thick base coat covered with a thin coat of render and small stones.
Cracks
Small cracks should be filled as with cracks in render.
'Blown' pebbledash
It could be the thin layer has separated from the thick base coat or the whole surface has
separated from the wall behind. Careully break away the loose area and determine the extent
of the damage.
If the thin top coat has separated, use a stabiliser to seal the surface and repair the
surface. If the damage is through to the wall, replace both surfaces in two stages, allowing
the thick base coat to dry before applying the thin pebbled layer.
If the pebbledash is to remain unpainted, try to use some of the original pebbles as
replacements. If the patch is too obvious and in a very public area, it may be worth considering
painting the wall for an alternative attractive finish.
