preparing exterior surfaces with a bleach solution

geordief

There are large areas where the growth is not too bad but I can see when look closely ( =put my glasses on!) that the alga etc is getting established.

No problem -I have applied a 1 to 3 bleach to water solution with a fairly vigorous rubbing in that I think will kill off this problem.

But my question is whether I now need (after giving the bleach a day or so to work) to wash the surface clean with water before I actually put on the paint (I mean there is a little dried scum left but not too much really and I have never bothered with this final wash before )

If the alga is completely killed will the (small) residue just blend into the new paint and not affect its adhesion in the long term?

deandean

I use 50/50 thin bleach and water, and apply using a garden sprayer. It degrades naturally over the course of a few days. For sure I would remove the dead algae before painting. Once it's dead and dried out I would have thought it comes off handy enough?

geordief

you mean to rub it away?

porte

Mix up a 60% water 40% bleach solution and brush onto your wall, after 24hr you can power wash off.
Choose a mildew-resistant paint.