Hi again,

On the painted exterior rendered walls of my house there are some areas
that have become coated with a typical very fine layer green stuff, mainly
where the wall is damp due to a leaking gutter which will be fixed shortly.
The green stuff is extremely thin. What is a cheap, effective, easy way to
kill or remove this, prior to painting with exterior emulsion?

Would household bleach work? It seems to work well on interior mildew.

Al