Painting a new wall

[BabsG]

In the autumn I had a new garden wall built which has a cement finish. Over the winter it has developed green algae in places. How do I prepare the surface before giving it the final coat of masonary paint? I have no wish to do it twice as it is quite long wall. Many thanks.

[woodchopper]

Power wash the wall lightly and then spray it withy a soution of Armillatox - available from garden centres - it will kill offf any remaining algae.
You will probaly have to give it two coats any way as it is a new wall or it will look patchy - may I suggest you use a roller for it and not a brush.

[BabsG]

Thanks woodchopper. I wasn't sure whether I needed to give it a coat of primer or not. Time to get the roller out.

[heathfield]

I'd do it the other way round to Woodchopper. Use the algicide/fungicide first, then lightly powerwash, or rinse and scrub the surface well using plenty of water and a sweeping brush. This way you won't be painting over dead algae still on the wall. Let everything dry thoroughly.

[BabsG]

Thanks heathfield. That makes sense.

[bricro1]

Ask yourself "do I really have to paint it?"
Once you start.....!!!

[BabsG]

I like the way you think bricro - but sadly it is about three feet from my kitchen window and looks hideous. So no option really.