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.
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.
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.
Do you have a question or comment about this topic? Click here to post your question/comment.
|Subject||Posted By||Replies||Posted at|
|There are currently no related questions for this topic.
Click here to post your question/comment.