[NavyB]

today's challenge ...

What does anyone suspect the staining on these rendered surfaces might be? (salts/rust/oxidisation/werid algae...

I belive the render is k-rend.

Any ideas re best solution/product to cleaning this off (& preventing it coming back)

[chris scott]

Red algae. Algoclear will kill/remove it. Repositioning the wall will prevent it coming back .

[NavyB]

Hey Chris nice one, does it make any difference that surface is K-Rend or is Algoclear safe as houses on this product?

I'm not sure the client will go for the repositioning of the wall into glorious sunshine 

[Fredd]

did you consult it to expert cleaners in your area?

[chris scott]

Hey Chris nice one, does it make any difference that surface is K-Rend or is Algoclear safe as houses on this product?

I'm not sure the client will go for the repositioning of the wall into glorious sunshine  

You are safe to use it on anything really…wood,plastic,render, concrete etc Try to keep it off the plants or grass…It won't kill them but does turn them a little yellow.
Is the gutter above the render leaking/blocked?