Water stains on crepi

[Angie]

Hi all.  Our house is six years old and has a light cream crepi wall finish.  From day one we experienced dirty walls as a result of the badly fitted guttering.  We had new guttering and downpipes fitted 18 months ago and although a lot better, if rain is heavy we get those horrible black marks (which look like black mould but aren't) all along the top ridge of the house.  We are now getting similar dirty black lines all along the front of our terrace which is unsightly and also at the edges of our windows.  I have attempted to clean this off with no success and am now contemplating buying a pressure washer to see if this will do the trick.  Has anyone had this problem and solved it.  Thanks as always

[Pierre ZFP]

You say it looks like black mould but isn't.  Do you know what it is?

I had some mould on a north facing wall and removed it with a spray of 'anti-mousse' (when it was on sale, about €5 for 5 litres) and then a week or two later, a blast from a pressure washer did the trick.  I now spray/blast once a year to keep it looking clean, Doesn't take long

[Angie]

Thanks for the advice Pierre.  I think its just dirt that spills over the roof, terrace or edges of the windows and eventually stains the crepi - I'm certain its not mould. Am going out to buy the pressure washer to see if that does the trick - we could do with one anyway.  Coming to think of it we have used one in the UK to clean our slabs and driveway with great success so fingers crossed it does the same on the walls.  Shall go lightly initially in case it blasts the plaster off!!  Thanks again

[Pierre ZFP]

Yes definitely go lightly, if there are any flaky bits they could easily be blasted off.

If it's just dirt then maybe some car wash shampoo or similar would help?

A job I have coming up is to clean the dirt and moss off my patio that has accumulated over the winter.  I'll wait for a nice day to do that!