Painting rendering covered with moss

[Peter Chapman]

The upper half of my house is rendered, not smooth render but, textured which seems to enhance moss growth to the extent that the rendering needs painting before the actual paint shows signs of ageing although it will last up to 5 years before the moss growth becomes too bad.

The moss grows on the East and North side of the house and has previously just been painted over with 2 coats each time.

Before I repeat the cycle, is there anything that can be done to reduce the re-appearance of the moss as in special paint or specific preparation prior to painting?

Grateful for any helpful suggestions/tips.

[Dave Liquorice]

Do you really mean moss or algae or lichen? Moss usually need more than just a painted surface to grow on.

Moss is also a small plant rather than a surface film. How ever painting directly over moss/algae/lichen without first removing it strikes me as a very bad idea. Both Sandtex and Dulux sell fungicdal washes which you apply and rinse off, I'd rinse with a pressure washer but at a distance and not with a "dirt blaster" type nozzle. This is preparation to get the paint film to adhere properly and last without flaking off.

If you current paint film is still sound it probably only needs a wash down, gentle pressure washer again. Some paints do have mold/algae inhibitors built in but I don't know how effective they are. The north and east facing wall will be prone to algae I doubt there is much you can do to prevent its growth.

[Tabby]

Textured render is much worse than smooth for this. If you decide to externally insulate, do render it smooth. Cut back overhanging trees and anything else that shades the house, thus increasing dampness. Adding a little powdered copper to the paint works wonders.

NT

[Peter Chapman]

Thanks for the useful suggestions guys. I have a better idea as to how to proceed.