Hi, I'm asking for a friend who is renovating a house. He wants to know the following, if any BM can help?

Cheers:

I have a tile roof on my house that has dirt and mildew on the outside of it. I want to repaint the tile with a different color, however, I need to prepare it before painting. Does anyone out there have experience on how to perform this? I have thought of bleach and water and also some type of caustic cleaner. If you have information on this subject and where to buy the cleaner please help me.

Thanks.

Maybe try a Jet washer first. But failing that a wire brush and lots of elbow grease or a wire brush on an angle grinder should fetch most of the heavy stuff off, you can then clean what remains with a strong floor cleaner such as Vixol that will get the mildew off.