In the past three decades or so self-finished renders have become popular. Architects liked the variety of finishes they offered – smooth, textured, mica sparkles, and colour pebbles to name a few – that were not so easy to obtain with paint. Householders liked them because of their easy, low maintenance. They need no painting, just a light clean every now and again. Builders liked them because there was no more hanging around waiting for paint to cure before completing the building. Unfortunately, largely because introducing modern wall insulation that has reduced the amount of heat moving through the walls. This has led to a build up of biological growth on the walls, mainly red, black, and green algae. Previously, the heat coming through the walls dried the render and so microbial growth, which likes damp conditions, was considerably less. This meant that walls now acquire very bad coloured staining from the algae, meaning that they need to be cleaned with high-quality biocide much more frequently – usually every three years or so.Why is Wall Render Presenting Problems Today?
Textured surfaces often pick up grime as well as hosting algae. Brushing a solution of Biocidal Wash into the surface using a soft brush quickly deals with this. We recommend frequently rinsing the dirt from the brush in a solution of biocide.
Green and red algae die in a few minutes following treatment. If the biofilm is very thick, a milky sheen will show for a short while before being dispersed by the wind. The orange pigment that comes from the red algae may stay for a bit but rain will soon wash away it away, on average in about 10 days.
Bacteria and Cyanobacteria will also die within a few minutes with our recommended dilution of Biocidal Wash. And the self-cleansing will continue for several days. Moulds are a group of fungi, the most common of which cause the black staining that protects them from ultra-violet light. They dig their way into the surface of render and even rock. Because of their tenacious nature, moulds are not as easy to treat as is algae. Although Benzs Biocidal Wash kills mould within a few minutes, the self-cleansing action will continue for several months. To speed this process up, rinse with plenty of fresh water a few days after treatment.