Rendered Walls, Buildings & Algae
In Cornwall and Devon, we have undertaken algal growth cleaning work on a variety of silicone based rend products and more standard rendered wall surfaces for green, red and black algae.
Due to the way in which algae spreads and then sustains itself, not many rendered surfaces can actually repel algal growths and poor property maintenance/building and render defects can help sustain quick algal growth. If you carry out algae treatments and you have not solved any regular wetting of the algae issues (if applicable) then it will return quite quickly.
Green Algae Green algae is probably the easier of three main algae to remove from rendered wall surfaces. Once we have established what is sustaining the algae, we then lightly spray on our environmentally friendly product and the algae is normally completely gone in three days although most of it has disappeared within 24 hours. Our process helps prevent costly redecoration and you do have to be very careful if you are thinking of painting over render and you must always take technical advice from the manufacturers before doing so.
Removal of red algae on rendered walls takes longer than green and we only need to lightly spray or soft wash our product on which normally needs no further action. The process for red algae, using our product with a good environmental foot print, takes between one to three weeks to remove it, depending on the environmental conditions.
Known as fungi is the most difficult type of algae to remove and it may take two treatments to either remove it or generally make it much better than it was. We always soft wash our product into the black algae and return again approximately two to three months later and retreat if necessary. We have enjoyed good success with black algae removal, although we cannot stress the importance of understanding if something is sustaining the algae then we would recommend carrying out remedial works to the building immediately to help the treatment be more effective and longer lasting.